GIS More Help

"Click link - See GIS data"
Good, fast, and free (for non-commercial use). Pick all three!
Gmap4 provides web GIS by combining Google maps
with a general purpose GIS viewer


No time to read this right now? OK. Just jump to the GIS example maps and take a quick look. You are almost certain to see something that you (1) find fascinating and (2) have never seen before on Google-map-based software. And if you find this GIS viewing feature to be particularly helpful, please keep in mind that Gmap4 is donate ware. Another way to support Gmap4 is to purchase a property line map.

You are reading the "GIS More Help" page. If you are already GIS savvy, you might prefer the version of this documentation that is on the GIS Help page.

If you are new to Gmap4 please take a moment to look at the FAQ and the examples page. You will quickly see how Gmap4 links are made. There is "Quick Start" information in a pdf file on the Gmap4 Help page.

Table of Contents - View GIS data with Gmap4

Part 1 - Using Gmap4 to view maps that show GIS data
     Introduction - Gmap4 is a GIS viewer
     Things you can do with GIS data after the map opens
     Importance of metadata
     How does this work? A peek under the hood

Part 2 - Specify GIS data in a Gmap4 link (Map-in-a-link)
     Gmap4 can display ArcGIS MapServer layers
     ArcGIS MapServer metadata
     Gmap4 can display ArcGIS ImageServer data
     ArcGIS ImageServer metadata
     How to make a Gmap4 link that displays GIS data
     Using the ll and z parameter with GIS data
     Add a map title
     Add a map legend
     Gmap4 can display WMS layers
     Limitations when displaying GIS data
     Web developers - Caution about using Gmap4 in iframes
     Miscellaneous tips and reminders

Part 3 - Specify GIS data in a text file
     How to specify GIS data in a text file
     Example text file specifying GIS data

Part 4 - Links to GIS servers
     USA federal sources for GIS data
     USA state sources for GIS data
     USA other sources for GIS data
     Canada sources for GIS data
     Australia source for GIS data
     How to Google search for ArcGIS data

Part 5 - Example Gmap4 links
     Example Gmap4 links showing GIS data - USA
     Example Gmap4 links showing GIS data - CANADA
     Example Gmap4 links showing GIS data - ENGLAND

Part 1 - Using Gmap4 to view maps that show GIS data

Introduction - Gmap4 is a GIS viewer

GIS stands for Geographical Information System. This technology works differently than downloading an entire file (GPX, KML, KMZ, etc). When you view GIS data the server hosting the data only sends you enough data to fill your screen. This data is delivered to your screen as a series of 'tiles'. Just like Gmap4 is a general purpose file viewing tool, it is now also a general purpose GIS viewer. This feature is known as "web GIS" since Gmap4 runs in your browser.

Why might you care? There is a vast amount of data on GIS servers that Gmap4 can display. Whatever your interest might be, there likely is data on a GIS server that you would enjoy seeing on a map. Some GIS data will be displayed as a new basemap with a solid background. Other GIS data will be displayed as transparent overlays that can be stacked on top of each other and then displayed on any basemap. Gmap4 lets you see both kinds of GIS data with familiar Google map controls.

You do not need to use complicated software that must be downloaded and installed in order to view GIS data. Instead, all you need to do is make a Gmap4 link that identifies the GIS data you want to view. And best of all, when you share your Gmap4 link with other people they do not need to know anything at all about GIS. All they need to know is "Click link - See GIS data".

You can open these links with most desktop browsers and with most browsers on most mobile devices including iPhones, iPads and Android devices. You can save any Gmap4 GIS link as a bookmark in your mobile browser and then quickly re-display that map anytime by opening that bookmark. When Gmap4 is opened on a smartphone or other mobile device it automatically displays an easy to use touch-friendly interface.

The data that you can now display by simply clicking a Gmap4 link is limited only by your ability to (1) locate that data on a GIS server and (2) make a proper Gmap4 link to display that data. These instructions and examples will get you going. Yes, there are a few new things you will need to learn. You can quickly get up to speed by reading these instructions and doing a bit of thoughtful experimentation. On your mark, get set, engage brain.

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Things you can do with GIS data after the map opens

GIS data can be added to the map as either (1) an additional basemap or (2) as a transparent overlay. After the map opens on your screen you can:
* Display any GIS basemap or any basemap hard-coded into Gmap4
* Switch any transparent overlay on/off
* Switch all transparent overlays on/off together
* Change the stacking order for the transparent overlays
* Click a GIS symbol and all the most recent attribute data for the thing that you clicked will be sent from the GIS server to your screen.

In addition, all of the Gmap4 features work just fine with GIS data. If you do Menu ==> "Link to this map" then you can copy a link that will reproduce the map you see on your screen complete with the GIS data. You can use the Menu ==> "My Location" feature and see your location on the map. You can display a USNG or UTM grid on top of the GIS data. You can display GPX, TPO, KML, KMZ, etc files on top of GIS data.

The following link opens a map that has one additional basemap and three overlays. Each overlay is produced by one "&wms=" or "&rest=" parameter in the Gmap4 link. Open this map and then open the basemap menu (button that says "All white basemap"). Basemaps that are hard-coded into Gmap4 appear in bold type while basemaps that are added as a result of parameters in the Gmap4 link appear in normal type. If any overlays are available for the map then they are listed in the "Overlay" section of the 'map type' menu.

Map with three transparent overlays
https://mappingsupport.com/p/gmap4.php?ll=38.548166,-99.162598&z=5&t=Weather_radar,Transportation,States&wms=https://nowcoast.noaa.gov/wms/com.esri.wms.Esrimap/obs?name=Weather_radar&layers=RAS_RIDGE_NEXRAD&transparent=true&version=1.1.1&rest=http://services.nationalmap.gov/ArcGIS/rest/services/transportation/MapServer?name=Transportation&layers=11,2&transparent=true&wms=http://webservices.nationalatlas.gov/wms?name=States&layers=states&transparent=true

Gmap4 always displays exactly one basemap. The name of the current basemap is always displayed on the button next to the Menu button. If a Gmap4 link includes a transparent overlay(s), then the "All white basemap" is automatically added to the list of map types. Sometimes a very nice way to present transparent GIS overlays is to display them on the "All white basemap".

An important concept for transparent overlays is their stacking order. Each overlay that is 'on' has a number assigned. Overlay #1 is at the bottom of the stack. The highest numbered overlay is at the top of the stack. Data on an overlay that is higher in the stack will cover up any data at the same location on overlays that are lower in the stack and also cover up any data in that same location on the basemap.

There are four things you can do with transparent overlays while viewing the map.

First, you can turn individual overlays on and off. Simply open the basemap menu. You will see a list of basemaps and a list of overlays. (Mobile users - Scroll down to the overlay section.) A few overlays are built in to Gmap4 and always appear in the overlay list. Click any of the overlay names. An overlay that is 'off' does not have a number assigned to it since it is not visible.

Second, you can turn all overlays on and off together. The overlay list includes two choices for this purpose. If you turn all overlays off and then turn them all back on then (1) all transparent overlays will be turned 'on' including any that were 'off' when the map opened and (2) the stacking order will be the order in which the &wms= and &rest= parameters appear in the Gmap4 link.

Third, you can change the stacking order. If you turn one overlay off then it is removed from the stack. If you then turn that same overlay back on it will be added to the top of the stack and data on this overlay will cover up any data at that same location that is present on the other overlays or on the basemap. Another way to change the stacking order is to turn all the overlays off and then turn them back on one at a time. The first overlay that you turn back on will be at the bottom of the stack and the last overlay you turn back on will be at the top of the stack.

Fourth, you can display GIS attribute data. Usually a GIS server has a variety of information about each GIS symbol you see on the map. If you click a GIS symbol then you will see all of the attribute data for the thing that you clicked.

GIS attribute data can be extremely useful! It is not unusual to see one or more attribute values that are links which lead to further information about the thing that you clicked.

Note! You can only display GIS attributes for the layer that is 'on top'. To find out which layer is 'on top', click the basemap button. The overlay layer with the highest number is 'on top'. Mobile users will need to scroll down to the "Overlay" section.

Tip for smartphone and tablet users. To save any Gmap4 link as a bookmark in the browser on your smartphone or tablet, email that link to yourself. Then open that link with your mobile browser and save it as a bookmark.

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Importance of metadata

The word "metadata" means information about data. A good example of metadata is the names of the layers of data on a GIS server. In order to make a Gmap4 link that will display GIS data when the link is clicked you usually will need to know the names of the layers of data that your map will display. In other words, you will need to know some metadata. In Part 2 of these instructions you will learn how to display the metadata from a GIS server.

How does this work? A peek under the hood

Think of a data file that shows the approximate boundary line of many different kinds of publically owned land across the USA. Such a data file would be huge. Now assume you only want to see a map for a small part of the USA. It would take a long time and waste resources to download that huge file to your computer when you only want to see a small part of that data.

GIS fills this need. Here is how it works.

Map software like Gmap4 always knows the latitude longitude values that define the portion of the world displayed on your screen. When you want to view data from a GIS server Gmap4 sends those latitude longitude values to that GIS server. In return, the GIS server sends back enough data to fill your screen. This data is delivered to you in a series of small files called "tiles". Each tile is 256 pixels wide by 256 pixels high and is either a jpg or png image. Sometimes if a GIS server is a bit slow you can see these tiles appear one at a time on your screen.

Be patient. If the server is extremely busy then it might take a few seconds for the server to send all the tiles to you that are needed to fill your screen. Occasionally you might not get any GIS data at all. Perhaps that server is off-line.

Tip: If some of the GIS tiles display on your screen but there are some that are obviously missing, try zooming in or out, wait for the tiles to display and then go back to the zoom level you want.

No GIS data on the screen? Try zooming in or zooming out. Some GIS servers only display data at certain zoom levels.

Part 2 - Making Gmap4 links to display GIS data

Gmap4 can display GIS data that is available via either the ArcGIS REST interface or WMS interface. The ArcGIS REST interface was developed by ESRI which is the leading vendor of GIS software. The WMS interface is open source. In the following sections you will learn how to make a Gmap4 link to display GIS data from both ArcGIS REST servers and WMS servers. In fact, GIS data from both types of servers can be combined in a single Gmap4 link.

For data that is available via the ArcGIS REST interface, there are three main ways that data is stored. They are called MapServer, ImageServer and FeatureServer. Gmap4 can display *any* user-specified MapServer and ImageServer data as long as the GIS server is one the public can access.

Most of the text and examples you see below show the GIS data being specified as parameters in the Gmap4 link. You can also specify that same GIS data in a text file. For more information, including the benefits of this approach, see
Part 3 - Specify GIS data in a text file

Tip: If the same data is available via both WMS and ArcGIS REST then use the ArcGIS REST server since your map might load faster. Also the ArcGIS REST metadata often has a better description of the data layers than the WMS metadata.

Gmap4 can display ArcGIS MapServer layers


Tip: You are reading the "GIS More Help" page. You can find another explanation on the
GIS Help page. Use the page that you find easiest to understand.

In general, there are several different ways that GIS data might be accessed. Many (but not all) servers that are hosting GIS data are setup to allow access via the ArcGIS REST interface and/or WMS (Web Mapping Service) interface. Some servers allow both interfaces and some only allow one or the other. For servers that offer both methods, you should choose ArcGIS REST since it might offer better performance than WMS. This section shows you how to make a Gmap4 link to display GIS data using the ArcGIS REST interface.

To make a Gmap4 link that will display GIS data using the ArcGIS REST interface, include one or more "&rest=" parameters in your Gmap4 link.

To add a basemap to the ones already hard-coded in Gmap4, write the "&rest=" parameter like this:
     &rest=________?name=________&layers=________&transparent=false

Replace the underlines as follows:
Underline 1: Full http link pointing to the GIS server directory that has the basemap data you want to display. Be sure to put a "?" after this link.
Underline 2: Short name you make up. Use an underline character instead of a space!
Underline 3: One or more layer numbers used on the server to identify layers of data. This can be a single number, a comma separated list, a range of numbers (layers=3-7) or a combination (layers=0,3-7,12).

To find http links for some GIS servers, see the section on this page titled Sources for GIS data. Of course you could also do a Google search.

The short name you make up is used by Gmap4 in the overlay menu and it is not used by the GIS server. If you forget to make up your own short name then a default name is assigned. That default short name is "GIS_" followed by a number.

To see how to find out the identifying numbers of the data layers on a GIS server, see the section on this page titled ArcGIS REST metadata.

To add a transparent overlay that can be displayed on top of any basemap and stacked with other REST and/or WMS overlays, write the "&rest=" parameter like this:

     &rest=________?name=________&layers=________&transparent=true

A Gmap4 link can include more than one "&rest=" and/or "&wms=" parameters. Also, be sure to put any "&wms=" and "&rest=" parameters at the end of the Gmap4 link. These two kinds of parameters can be in any order. They just need to be at the end of the Gmap4 link.

For example, when the following map opens the basemap is the Google aerial and much of California will be displayed. On top of that basemap will be a transparent overlay showing the county boundaries and county names.

County boundary map
https://mappingsupport.com/p/gmap4.php?ll=37.877021,-121.14624&z=9&t=h,Counties&rest=http://services.nationalmap.gov/ArcGIS/rest/services/govunits/MapServer?name=Counties&layers=3,13&transparent=true

If occasionally the GIS data seems to be incomplete, try zooming in or out. Wait for the GIS data to appear on your screen and then change the zoom level to the one you really want.

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ArcGIS MapServer metadata

This section uses ArcGIS REST metadata from the U.S. Forest Service as an example.

When you are looking for ArcGIS REST metadata on a website look for links labelled "REST service", "REST endpoint" or something similar. Sometimes a link labelled "Web Mapping Service" (WMS) will also lead to REST metadata.

Please open the following Forest Service link:
https://apps.fs.fed.us/ArcX/rest/services/EDW

The EDW screen lists several dozen kinds of data. As long as the end of a line says "MapServer" or "ImageServer", Gmap4 can display that data. Sometimes you will see "Feature Service" or WFS on similar lists. Gmap4 cannot presently display Feature Service data. So you want to make sure that information you are trying to view with Gmap4 is identified as "MapServer" or "ImageServer" in the metadata.

Now look toward the bottom of the EDW list and click the link for "EDW/EDW_Wilderness_01 (MapServer)".

1. After the screen refreshes go to the bottom of this screen. Make sure that:
      A. The heading "Supported Operations" includes "Export Map"
      B. The heading "Supported Interfaces" includes "REST"

2. Near the top of the screen, find the heading "Layers". Under this heading is a list of one or more layers of data that Gmap4 can display. Each layer has a number and a descriptive name. Use the number in the Gmap4 link and not the descriptive name. For example, to display layer 0 your Gmap4 link would include &layers=0.

3. Near the top of the screen, find the heading "Single Fused Map Cache". Usually this value will be "false". This means that when you ask the GIS server to send you enough tiles to fill your screen, the server produces those tiles on-the-fly in response to your request. These are called "dynamic" tiles. This type of layer may or may not be designed so you can display it as a transparent overlay. The easiest way for you to find out if a layer can be displayed as a transparent overlay (instead of a non-transparent basemap) is to make a Gmap4 link yourself and test the layer.
   Sometimes the value for "Single Fused Map Cache" will be "true". This means that the GIS server has pre-made tiles all ready to go. These are called "cached" tiles and they usually display faster than dynamic tiles. Often times cached tiles include data from several different dynamic layers. Since all of this data is combined in the process of making the tiles and storing them in the cache, you will not be able to turn individual layers on/off. In other words, when you are displaying cached tiles, all the individual layers have been combined into a single layer.

4. Find the heading "Supported Interfaces" again near the bottom of the screen. If it also says WMS then this same data is available via both the ArcGIS REST interface and the WMS interface. I recommend you always use the ArcGIS REST interface when given the choice since performance may be better than the WMS interface.

Tip: You may have to zoom in to see the GIS data. When you see some GIS data you may need to zoom in more to see all the GIS data.

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Gmap4 can display ArcGIS ImageServer data

By default, Gmap4 always treats ImageServer data as an additional basemap, not as an overlay.

To make a Gmap4 link that will add ArcGIS ImageServer data to the list of basemaps that Gmap4 can display, include one or more "&rest=" parameters in your Gmap4 link. Make your Gmap4 link like this:
     &rest=________?name=________

Replace the underlines as follows:
Underline 1: Full http link pointing to the GIS server directory that has the basemap data you want to display. Be sure to put a "?" after this link.
Underline 2: Short name you make up. Use an underline character instead of a space!

The short name you make up is used by Gmap4 in the basemap menu and it is not used by the GIS server. If you forget to make up your own short name then a default name is assigned. That default short name is "GIS_" followed by a number.

A Gmap4 link can include more than one "&rest=" parameter. Also, be sure to put any "&rest=" parameters at the end of the Gmap4 link.

Below is an example map that displays aerial photos for the state of Ohio. This ImageServer data is hosted on a GIS server operated by the state. When the map opens it is zoomed in on a random spot and the basemap "Ohio_aerial" is displayed.

Ohio aerial photos:
https://mappingsupport.com/p/gmap4.php?ll=39.628602,-82.267920&z=17&t=Ohio_aerial&rest=https://geo.oit.ohio.gov/arcgis/rest/services/OSIP/osip_best_avail_1ft/ImageServer?name=Ohio_aerial

*** Note on the above map the trail running north-south. Now switch to the Google aerial and the trail disappears since the aerial photos Google usually uses are taken when the leaves are on the trees. By contrast, states and local governments may have aerial photos taken when there are no leaves on the trees and as a result you can see the ground.

*** Now switch the basemap to "usgs - Aerial USA partial". Note that these aerial photos (hosted by the USGS) are the same as the aerial photos displayed by the basemap "Ohio_aerial" (hosted by the State of Ohio). You should easy be able to see that the "Ohio_aerial" is a crisper image. This is likely due to heavy compression of the aerials on the USGS server.

TIP: Like you see on the above example map, sometimes state, county or city GIS servers have excellent quality aerial photos that Gmap4 can display and these photos might display information that you cannot see on Google's aerials.

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ArcGIS ImageServer metadata

Since most ImageServer data is aerial photography, there is only a modest amount of metadata that it will be useful for you to know. That metadata can be found in the index to the GIS server. That index is simply a bunch of web pages. For example, below is the index page for the ImageServer data that is aerial photography for the state of Ohio. These Ohio aerials are displayed by the map in the prior section.

https://geo.oit.ohio.gov/arcgis/rest/services/OSIP/osip_best_avail_1ft/ImageServer

The metadata you see on the above link tells you the year during which the aerial photos were taken for each county.

When you are looking at a Gmap4 map that displays GIS data and you want to see the GIS metadata, then look at the Gmap4 link. (To get the Gmap4 link you can do Menu ==> Link to this map.) If you see a "rest=" parameter then follow that link to the metadata on the GIS server. Otherwise you will see a "q=" parameter pointing to a txt file. Download that txt file and open it. You will find at least one and likely several "rest=" parameters pointing to index pages on GIS servers.

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How to make a Gmap4 link that displays GIS data

Here is an easy way to get Gmap4 to make a link for you that will display a map that is (1) centered anywhere you want on the planet (except really close to the north pole or south pole), (2) be zoomed to the level you want and (3) show the GIS data you want to see when the link is clicked.

Step 1. Find the GIS data you want to see and build a very basic Gmap4 link.

This demo will use ArcGIS MapServer layers that show interstate roads and counties.. Below are the links that point to this GIS data. To see the metadata, follow the link to the GIS server and then follow the link to the layer number.

Interstate roads (layer 2 from a NOAA GIS server):
&rest=
http://geocommunicator.gov/ARCGIS/REST/services/Basemaps/MapServer

Counties (layer 1 from a BLM GIS server):
&rest=https://nowcoast.noaa.gov/arcgis/rest/services/nowcoast/mapoverlays_political/MapServer

Here is a very basic Gmap4 link. Notice that this link does not have a ll (map center) or z (zoom level) parameter. It also does not have a t parameter (used to turn on the GIS data when the map opens).

When you open the following map it will display the Gmap4 default map of the world.

https://mappingsupport.com/p/gmap4.php?rest=http://geocommunicator.gov/ARCGIS/REST/services/Basemaps/MapServer?name=Interstate_highway&layers=1&transparent=true&rest=https://nowcoast.noaa.gov/arcgis/rest/services/nowcoast/mapoverlays_political/MapServer?name=County&layers=2&transparent=true

Step 2. Make the map look the way you want it to look on your screen.

A fast way to pan and zoom the map to a place you want to see is to use Menu ==> Search. After the search is done, remember to close the search bar.

To turn on the two transparent overlays, click the basemap button (it is next to the "Menu" button), go to the "Overlay" section (mobile users scroll down) and click on the Interstate and County overlays. Keep in mind that the transparent overlays stack on top of each other. Data on a higher numbered overlay will cover up data on a lower numbered overlay. To change the stacking order, turn all the overlays off and then turn them on in a different order.

Note: You have to be zoomed in somewhat before the county data appears.

You can click the layer that is 'on top' and a popup will appear with all the attribute data the GIS server has for the thing that you clicked.

Select the basemap you want to have displayed when the map opens. Keep in mind that GIS data is seen by Gmap4 as a series of jpg or png image 'tiles' and Gmap4 does not have any way to alter anything on those images. Different GIS data will look better on different basemaps. Experiment. Some GIS data will look great (or at least be easier to read) on the "All white basemap" together with another layer that is an outline of the states.

Fine tune the center of the map by dragging the map and adjust the zoom if needed.

Step 3. Ask Gmap4 to make the map link for you

Click Menu ==> Link to this map. The link you see will reproduce the map you have on your screen.

Look closely at the link and you will see that the following additional parameters have been added just after the first "?" in the link:
"ll=" Latitude and longitude (WGS84 datum) for the center of the map.
"z=" Zoom level. A rightclick on a desktop also displays the zoom level.
"t=" Comma-separated list (no spaces) of one basemap and any transparent overlays that display when the map opens.

A Gmap4 map always displays one and only one basemap. When the "&t=" parameter points to a list of map types, there should not be more than one basemap in the list and any additional basemaps in this list are ignored. If the "&t=" parameter does not include any of the basemaps then:
     A. If there is no "&t=" parameter in the Gmap4 link, then the t1 (Google terrain) basemap will be displayed.
     B. If the "&t=" parameter only lists the names of one or more transparent overlays, then the "All white basemap" will be displayed.

The map types in the "&t=" list that are transparent overlays are stacked in this order when the map is opened: 1,2,3,etc. Thus, the last overlay in the "&t=" list is at the top of the stack (i.e. has the highest number) and data on this 'highest' overlay will cover up data on all the other overlays.

The order of the &rest= and &wms= parameters in the Gmap4 link should likely match the stacking order shown by the overlay names in the &t= parameter of the Gmap4 link. Here is the reason. At the bottom of the 'Overlay' menu are two choices that say "Remove all overlays" and "Display all overlays". Choosing "Remove all" turns off all of the transparent overlays. Choosing "Display all" turns all of the overlays on even if some of them were not turned on by the &t= parameter when the map first opened. The stacking order that results from "Display all" is the order of the &rest= and &wms= parameters in the Gmap4 link.

Notice that the short name you make up for each &rest= and &wms= parameter in your Gmap4 link is used in the 'Basemap' and 'Overlay' menus and maybe in the "&t=" parameter list. If you forget to make up you own short name then a default name is assigned. That default short name is "GIS_" followed by a number.

There are two situations where you usually should delete the "ll=" and "z=" parameter from the link produced by Gmap4. First, the "q=" parameter is used to display a GPX, KML, KMZ and certain other file types. If the Gmap4 link *does not* include a ll or z parameter then the program will automatically center and zoom the map such that all of the data in the file is on the user's screen irrespective of screen size. Second, if the Gmap4 link contains a "&markers=" parameter then you need to look a bit closer. Sometimes the "&markers=" parameter will contain coordinate data. When that is the case, you likely should not have any ll or z parameter in the Gmap4 link and instead let the program automatically center and zoom the map such that all the data in the "&markers=" parameter is on the map.

You should assume that people with many different sizes of screens - from smartphones to desktops - will be viewing your map. If your map displays (1) data from a file or (2) coordinate data via the "&markers=" parameter, then usually your Gmap4 link should not include the "ll=" and "z=" parameters. If those two parameters are not in the link, then Gmap4 will automatically center and zoom the map such that all of the data from the file or "&markers=" parameter is on the user's screen irrespective of the size or resolution of that screen.

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Add a map title

You can add a title to a map by using the "&markers=" parameter. The title will be displayed in the upper left corner of the map. Here are some examples:

&markers=title=MyTitleHere

&markers=title=<b>My%20Title%20Here</b>

&markers=title=<b>Line1<br%20/>Line2</b>

&markers=title<div%20style="font-weight:bold;">=<b>Line1<br%20/>Line2</b></div>

The characters %20 are computer-speak for a space. Often times a space in a link will cause problems so use %20 instead of a space.

The last three examples will cause the title to appear in bold type. The 3rd and 4th examples have a title that appears on two lines. The last example uses inline CSS to style the title.

The location of the markers parameter in the Gmap4 link is important. Place the markers parameter right before the first wms or rest parameter.

For an example of a map link with a title, see the "Earthquake Risk" map in the section titled
"Example Gmap4 links showing GIS data" further below.

The markers parameter can do a lot more besides add a title to the map. For more information about this feature please go to the Gmap4 help page and download the pdf file 'Delimited Text Data' and search that file on 'markers'.


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Using the ll and z parameter with GIS data

Gmap4 can display:
1. Data stored in a file that is online, or
2. Data stored in the Gmap4 link (map-in-a-link), or
3. Data stored on a GIS server, or
4. Data stored on a GIS server together with either #1 or #2.

When Gmap4 displays data stored in a file or map-in-a-link, then you do not need to specify the ll and z parameters in the Gmap4 link. If such a Gmap4 link does not include a ll or z parameter, then the map will open and automatically be centered and zoomed such that all of the data from the file or map-in-a-link is on the user's screen. It works this way on any size screen from smartphones to desktops. For example, the following link displays a KML file. Note that the link does not have either a ll or z parameter.

https://mappingsupport.com/p/gmap4.php?q=https://mappingsupport.com/p/gmap4/helpfile/Stafford_Creek.kml&t=t4

By contrast, Gmap4 does not know anything about the content of GIS data. If you make a Gmap4 link that only displays GIS data and the link does not include a ll and z parameter then be default when your map opens on the screen it will be zoomed way out. On a desktop, the default is to show a map of the world.

Therefore, if you make a Gmap4 link to display GIS data and not data from any file, then if you want the map to open and already be zoomed in somewhere you need to include a ll and z parameter in the Gmap4 link. The ll parameter specifies the latitude,longitude for the map center and the z parameter specifies the zoom level.

In picking a ll and z parameter to use, keep in mind that there are all kinds of screen sizes from smartphones to extra large desktops. On a 1280x1024 screen the following link shows (1) all of the 'lower 48' states from the west coast over to the middle of New Hampshire and (2) most of Cuba. If you open the same link with most smartphones, you will only see the central part of the USA.

https://mappingsupport.com/p/gmap4.php?ll=35.960476,-96.81491&t=m&z=5

Usually if you make a Gmap4 link that (1) shows GIS data and (2) does not show data from a file, then you should include a z and ll parameter in the Gmap4 link in order to zoom and center that map such that the GIS data is displayed on the screen when the map opens. Remember that the Menu ==> 'Link to this map' feature of Gmap4 will display a link that includes a z and ll parameter. That link will reproduce the map you see on your screen.

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Add a map legend

If you are making a Gmap4 link that uses the WMS interface to display GIS data then there likely is a graphic file already made that contains a legend for that data. The metadata for that WMS service includes a link for that graphic file. If you include that link in a title on your map, then people viewing your map will have an easy way to see the legend simply by clicking that link.

To find the link to the legend image open the WMS metadata and find the entry for the GIS data your map is displaying. Then look down until you see "LegendURL" and there is the link to the legend image.

Copy that link and paste it into a browser to see the legend image and decide if it is something you would like to use. Bad news. Some of these legend images are so small that they are illegible. If you find a poor quality legend then email the people responsible for the WMS data and ask them to produce a legend that is legible when the legend link is used in a browser.

Use the "&markers=" parameter to add a title to your map that contains a link to the legend image. Below is a suggested standard way to make a map title that includes a legend. Replace the first underline with the title of your map. Replace the second underline with the link to the image with the legend. %20 is computer-speak for a space and is used since spaces in links often cause problems. If your map title includes any spaces then use %20 instead of a space.

&markers=title=<b>__________<br%20/><a href='__________'%20target='_blank'>Legend</a></b>

And here is an example showing how the above format is used to place a title and legend link on the "Earthquake Risk" map in the section of example maps further down on this page.

&markers=title=<b>Earthquake%20Risk<br%20/><a href="http://webservices.nationalatlas.gov/wms?version=1.3.0&service=WMS&request=GetLegendGraphic&sld_version=1.1.0&layer=seihaz&format=image/png&STYLE=default'%20target='_blank'>Legend</a></b>

Data that Gmap4 can display via the ArcGIS REST interface also often has a map legend. Look at the ArcGIS REST metadata that lists the various layers. Just above that list of layers, look for a link labelled "Legend".

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Gmap4 can display WMS layers

If you have the option of displaying the same data via WMS or via the ArcGIS REST interface, then you should choose the ArcGIS option. That option is easier to use, the map will likely display faster and you can display a legend.

But if the data you want to view is only available via WMS then the documentation for displaying that data with Gmap4 is on this
WMS page.

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Limitations when displaying GIS data

Gmap4 does not have any way to know anything about the nature of the data on the tiles that a GIS server puts on your screen. In other words, Gmap4 cannot change the line width or line color of GIS data.

If the GIS tiles are grossly misaligned then try using the basemap "m" (Google street map) in your Gmap4 link. This problem appears to be a Google bug.

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Web developers - Caution about using Gmap4 in iframes

This section is for people that design web pages. If that is not you then you can skip this section.

The issue of embedding Gmap4 in an iframe is important because (1) each time Gmap4 starts the Google map Application Program Interface (API) is loaded and (2) after Gmap4 loads that API 25,000 times on average in one day then I have to pay Google for additional API loads in that same day otherwise Gmap4 stops working until the next day.

You can read more about this pricing policy at:
https://developers.google.com/maps/documentation/javascript/usage

Each time someone looks at a web page that includes Gmap4 embedded in an iframe, the Google map API is loaded. If the person viewing that web page is doing so because of some other content on that page and does not care about the embedded map, then that API load is 'wasted'.

Bottomline: You are welcome to embed one Gmap4 map per webpage as long as you design that page with care so a person looking at that page most likely wants to see the map. For example, it is fine to embed a Gmap4 map in an iframe on a web page that describes a specific trail.

If you do use an embedded Gmap4 map then it is a 'best practice' to include a link to a full screen map under the embedded map.

Remember, Gmap4 is free for non-commercial use.

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Miscellaneous tips and reminders

GIS overlay data covers up data on the basemap.

Transparent GIS overlays that are higher in the stack cover up transparent GIS overlays that are lower in the stack.

Sometimes the only way to tell for certain if a GIS layer has a background that can be transparent is to make a Gmap4 link and test it.

Put all "&rest=" and "&wms=" parameters at the end of the Gmap4 link.

The default basemap is either "t1" (Google terrain) or "All white basemap" depending on how the Gmap4 link is written.

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Part 3 - Specify GIS data in a text file

How to specify GIS data in a text file

Instead of specifying GIS data right in a Gmap4 link, you can specify the same GIS data by using a text file. If you then put that text file online and make a Gmap4 link to display that file, you will get the exact same map that you would see if you specified the GIS data right in a Gmap4 link. You can specify a combined maximum of 25 GIS basemaps and overlays.

Depending on your circumstances, you might prefer to specify GIS data in a text file for three reasons. First, you will get a shorter Gmap4 link that most email and forum software will process correctly. Second, if the GIS administrator changes the address of the data you are accessing then your map will stop displaying that data. You can then make a corresponding tweak in your text file without having to make a new Gmap4 link. Third, you can add/delete GIS references in the text file without having to change your actual Gmap4 link since your Gmap4 link will simply point to your text file, like so:
https://mappingsupport.com/p/gmap4.php?q=____________
Put your text file online and replace the underline with the http link to your text file.

When you make a text file to specify GIS data, you use the exact same syntax that you would use if you were specifying the same GIS data right in the Gmap4 link. Each line in your file that specifies some GIS data will start with either rest= or wms=. See Part 2 (above) for the details of this syntax. The next section includes an example map with a number of GIS layers and a link to the text file. If you download that text file and open it, you will easily see how to make similar text files.

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Example text file specifying GIS data

Note that the following Gmap4 link points to a text file. That file specifies a number of GIS layers. When this map opens it displays the boundary for wilderness areas and is centered to show the western USA. If you zoom in one tick then a different GIS layer displays names for those wilderness areas. If you open the basemap menu then you will see additional GIS layers that you can turn on/off and restack.
https://mappingsupport.com/p/gmap4.php?ll=39.470125,-113.554687&z=5&t=USA_basemap_shaded,Wilderness_boundary,Wilderness_names&q=https://mappingsupport.com/p/help/demo_gmap4_with_gis_layers.txt

And here is a link to the text file that is used to produce the above map.
https://mappingsupport.com/p/help/demo_gmap4_with_gis_layers.txt

Tip: A text file can do a lot more than just specify GIS data for Gmap4. For more information about sending data to Gmap4 via a text file, please go to the Gmap4 help page and download the pdf file 'Delimited Text Data'.

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Part 4 - Links for GIS servers

Below are various sources for GIS data that are available via ArcGIS REST and/or WMS. If you see any bad links or have a suggestion for additional sources to add to this list, please send me an email.

This list of GIS servers is certain to be incomplete. No doubt the federal departments and states listed below have other GIS servers that are not listed here. Most of these GIS server links were found by searching with Google. Unfortunately, many federal agencies and states do not provide any easy way (or even a hard way) to go to their website and get a list of the GIS servers that hold their public data.

Where is the metadata?

The ArcGIS links listed below will lead you to GIS index pages that each show one or more layers of data. Each GIS index page that lists data layer(s) should have a bold heading near the top that says "Service Description". That description should have a few lines of metadata describing the nature of the information contained in the data layer(s) listed on that page. Unfortunately you will discover that in the great majority of cases that description field is blank. Each GIS index page that lists data layer(s) should have something more than nothing in the "Service Description" to help everyone quickly and easily understand the nature of the information contained in the data layer(s) listed on that page.

Why are GIS attribute names gibberish?

When you are looking at a Gmap4 map and click on a GIS symbol then a popup will usually be displayed that shows a list of attribute names and values. Take a look at the attribute names. Way too often instead of being reasonably clear the attribute names are cryptic gibberish. This type of obfuscation makes it hard-to-impossible for anyone who is not an 'insider' to understand what information is being conveyed by such attributes. In order to get the most value out of GIS data, much of which was collected at taxpayer expense, gibberish attribute names need to be banned.

A related problem is attribute values that are coded. This is another type of obfuscation. Consider an attribute named "Evacuation route priority" that has values of 1, 2 or 3. Picture yourself in a car attempting to flee an approaching hurricane. Should you pick a #1 route or #3 route? The GIS server cannot answer this question since the meaning behind the codes is not disclosed.

Here is one possible solution for coded attribute values. Each GIS data layer that uses any coded values should have an additional attribute with a name something like "Data code definitions". The value for this attribute should be a clickable link to a PDF file or HTML page that lists the data codes used in that GIS layer and the meaning of each code.

Link status

March 2015: All of the following links should be good.
Please report broken links.

USA federal sources for GIS data

The two sections above titled ArcGIS REST metadata and WMS metadata explain how to use these links. If you have not yet read those sections, then now would be a good time to do so.

This is only a partial list of federal sources that have GIS data that you can view simply by making a Gmap4 link.

National Map
USA federal government
ArcGIS: https://viewer.nationalmap.gov/services/
Homepage: http://nationalmap.gov/

NOAA - Weather data

National Weather Service (NWS) - Master GIS list of layers:
http://gis.srh.noaa.gov/ArcGIS/rest/services

This page leads to a subset of the National Weather Service master list but likely will be helpful the first time you look at this information.
http://nws.noaa.gov/gis/otherpage.html

Lots more GIS weather data from the Office of Coast Survey:
https://nowcoast.noaa.gov/arcgis/rest/services/nowcoast

NOAA - Coastal charts and more from the Office of Coast Survey

Here are NOAA's Raster Navigation Charts. The charts are layer 3.
https://seamlessrnc.nauticalcharts.noaa.gov/arcgis/rest/services/RNC/NOAA_RNC/MapServer

And here is large amount of layers related to the coast. To access the individual layers that are combined to make the charts, drill down on the "encdirect" folder.
http://encdirect.noaa.gov/arcgis/rest/services

Wrecks and obstructions:
http://wrecks.nauticalcharts.noaa.gov/arcgis/rest/services/public_wrecks/Wrecks_And_Obstructions/MapServer

NOAA - National Geophysical Data Center
https://maps.ngdc.noaa.gov/arcgis/rest/services

Bureau of Ocean Energy Management (BOEM)
ArcGIS: http://gis.boemre.gov/arcgis/rest/services
ArcGIS: http://oceanenergy.boemre.gov/arcgis/rest/services

National Park Service (NPS)
ArcGIS: http://irmaservices.nps.gov/arcgis/rest/services
ArcGIS: https://mapservices.nps.gov/arcgis/rest/services
ArcGIS: http://mobilegis.nps.gov/arcgis/rest/services
ArcGIS: https://imgis.nps.gov/arcgis/rest/services

U.S. Forest Service (USFS)
ArcGIS: https://apps.fs.fed.us/ArcX/rest/services/EDW/
ArcGIS: http://foresthealth.fs.usda.gov/arcgisfh/rest/services

Bureau of Land Management (BLM)
ArcGIS: http://geocommunicator.gov/ArcGIS/rest/services
ArcGIS: http://landscape.blm.gov/ArcGIS/rest/services
ArcGIS: https://eplanspatial.blm.gov/arcgis/rest/services

U.S. Geological Survey (USGS)
ArcGIS: http://hdds.usgs.gov/ArcGIS/rest/services
ArcGIS: http://eerscmap.usgs.gov/arcgis/rest/services
ArcGIS: http://gis1.usgs.gov/arcgis/rest/services
ArcGIS: http://isse.cr.usgs.gov/ArcGIS/rest/services
ArcGIS: http://rmgsc.cr.usgs.gov/ArcGIS/rest/services

U.S. Fish and Wildlife Service
ArcGIS: http://107.20.228.18/ArcGIS/rest/services
ArcGIS: http://gis.fws.gov/arcgis/rest/services
ArcGIS: http://criticalhabitat.fws.gov/arcgis/rest/services
ArcGIS: http://ecos.fws.gov/arcgis/rest/services

Environmental Protection Agency (EPA)
metadata: http://water.epa.gov/scitech/datait/tools/waters/services/mapping_services.cfm
ArcGIS: http://geodata.epa.gov/arcgis/rest/services
ArcGIS: http://epamap23.epa.gov/ArcGIS/rest/services
ArcGIS: http://watersgeo.epa.gov/ArcGIS/rest/services
ArcGIS: https://edg.epa.gov/ArcGIS/rest/services

Federal Emergency Management Agency (FEMA)
ArcGIS: http://gis.fema.gov/REST/services
ArcGIS: https://hazards.fema.gov/gis/nfhl/rest/services
ArcGIS: https://services.femadata.com/arcgis/rest/services

US Army Corps of Engineers (ASACE)
ArcGIS: http://rsc-agisu.usace.army.mil/s1arcgis/rest/services
ArcGIS: http://gis.sam.usace.army.mil/server/rest/services
ArcGIS: http://155.82.170.101:8399/arcgis/rest/services

U.S. Department of Agriculture (USDA)
ArcGIS: http://gis.apfo.usda.gov/arcgis/rest/services
ArcGIS: http://gdwweb1.ftw.nrcs.usda.gov/arcgis/rest/services

U.S. Census
ArcGIS: http://tigerweb.geo.census.gov/arcgis/rest/services

U.S. Post Office (USPS)
ArcGIS: https://gis.usps.com/arcgis/rest/services/EDDM/EDDM_ZIP5/MapServer

U.S. Department of Transportation
ArcGIS: http://gis.rita.dot.gov/ArcGIS/rest/services

U.S. Department of Energy
ArcGIS: http://solarmapper.anl.gov/ArcGIS/rest/services
ArcGIS: http://gisatnrel.nrel.gov/ArcGIS/rest/services
ArcGIS: http://107.22.45.173/ArcGIS/rest/services

U.S. Department of Housing and Urban Development
ArcGIS: http://egis.hud.gov/ArcGIS/rest/services

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USA state sources for GIS data

The sections ArcGIS REST metadata and WMS metadata explain how to use these links. If you have not yet read those sections, then now would be a good time to do so.

Please let me know about any links that die.
If you are on a state website and find a source for GIS data that is not listed below and that data is available via either ArcGIS REST or WMS, please send me an email and I will add that data source to this list.

Multi-state recreation
ArcGIS: http://gis.landscope.org/arcgis/rest/services/LandScope/LS1_Recreation/MapServer

Alabama
ArcGIS: https://conservationgis.alabama.gov/adcnrweb/rest/services
ArcGIS: https://maps.alabama.gov/algogis/rest/services
ArcGIS: http://map.gsa.state.al.us/ogbmaps/rest/services
ArcGIS: http://map.ogb.state.al.us/ogbmaps/rest/services

Alaska
ArcGIS: http://dmlwmaps.dnr.alaska.gov/agsweb/rest/services
ArcGIS: http://gis.tananachiefs.org/arcgis/rest/services
ArcGIS: http://dec.alaska.gov/arcgis/rest/services
ArcGIS: http://forestrymaps.alaska.gov/arcgis/rest/services

Links to data layers: http://alaskamapped.org/data/wms-wfs-wcs-web-service-feeds
Several WMS URLs are listed a short way down on this page.

FAA charts: http://wms.alaskamapped.org/faa_charts?REQUEST=Getcapabilities

Links to data layers: http://docs.gina.alaska.edu/tiles/merc.html

Arizona
ArcGIS: http://arcgis.azgfdportal.com/arcgis/rest/services
ArcGIS: https://azhgis2.esri.com/arcgis/rest/services
ArcGIS: http://dproxy.azdot.gov/ArcGIS/rest/services
ArcGIS: http://imagery.azmap.org/ArcGIS/rest/services
    Related homepage: http://sco.azland.gov/imagery.htm

Arkansas
ArcGIS: http://geostor.arkansas.gov/ArcGIS/rest/services
ArcGIS: http://gis.arkansas.gov/arcgis/rest/services
ArcGIS: http://gis.agfc.com/arcgis/rest/services

California    Go to the Gmap4 GIS maps for California
ArcGIS: http://atlas.resources.ca.gov/ArcGIS/rest/services
ArcGIS: https://map.dfg.ca.gov/arcgis/rest/services
ArcGIS: https://services.gis.ca.gov/arcgis/rest/services
ArcGIS: http://conservation1.arcgisonline.com/arcgis/rest/services
ArcGIS: http://conservation2.arcgisonline.com/arcgis/rest/services
ArcGIS: http://conservation3.arcgisonline.com/arcgis/rest/services
ArcGIS: http://gis.abag.ca.gov/arcgis/rest/services
ArcGIS: http://casgemgis.water.ca.gov/ArcGIS/rest/services
ArcGIS: https://gis.water.ca.gov/arcgis/rest/services/Public
WMS: http://earth.dot.ca.gov/geoserver/wms?request=GetCapabilities&service=WMS&version=1.1.1

Colorado
ArcGIS: http://ndismaps.nrel.colostate.edu/arcgis/rest/services
ArcGIS: http://dtdapps.coloradodot.info/arcgis/rest/services
ArcGIS: http://coephtmaps.dphe.state.co.us/arcgis/rest/services
ArcGIS: http://maps.dphe.state.co.us/ArcGIS/rest/services
ArcGIS: http://maps.co.gov/COPubGIS/rest/services

Connecticut
ArcGIS: http://ctecoapp1.uconn.edu/ArcGIS/rest/services
ArcGIS: http://ctecoapp2.uconn.edu/ArcGIS/rest/services/maps
ArcGIS: http://ctgismaps2.ct.gov/arcgis/rest/services

University of Connecticut - MAGIC. Historical maps and more.
WMS: http://magic.lib.uconn.edu/help/help_WMS.htm
WMS: http://72.248.187.142/wms/wms.exe?request=getcapabilities&service=wms

Delaware
ArcGIS: http://mapservices.dnrec.delaware.gov/ArcGIS/rest/services
ArcGIS: http://broadband.delaware.gov/arcgis/rest/services
ArcGIS: http://firstmap.gis.delaware.gov/arcgis/rest/services

University of Delaware Environmental Monitoring and Analysis Center
Scroll down for WMS URL: http://demac.udel.edu/data/aerial-photography

Florida    Go to the Gmap4 GIS maps for Florida
ArcGIS: http://map.floridadisaster.org/GIS/rest/services
ArcGIS: http://ca.dep.state.fl.us/arcgis/rest/services
ArcGIS: http://castg.dep.state.fl.us/arcgis/rest/services
ArcGIS: http://ocean.floridamarine.org/arcgis/rest/services
ArcGIS: http://gis.doh.state.fl.us/ArcGIS/rest/services

Georgia
ArcGIS: http://gis10.dot.ga.gov/ArcGIS/rest/services
ArcGIS: http://maps.crc.ga.gov/crcarcgis/rest/services
ArcGIS: http://maps.itos.uga.edu/arcgis/rest/services

Hawaii
ArcGIS: http://gis.hawaii.gov/arcgis/rest/services
ArcGIS: http://maps.hawaii.gov/ArcGIS/rest/services

Idaho
ArcGIS: https://insideidaho.org/ArcGIS/rest/services
ArcGIS: http://cloud.insideidaho.org/ArcGIS/rest/services
ArcGIS: http://gis.idaho.gov/ArcGIS/rest/services
ArcGIS: https://maps.idwr.idaho.gov/arcgis/rest/services
ArcGIS: http://fishandgame.idaho.gov/gis/rest/services
ArcGIS: http://global.deq.idaho.gov/arcgis/rest/services

Illinois
ArcGIS: http://geoservices.epa.illinois.gov/arcgis/rest/services
ArcGIS: http://geoservices.dnr.illinois.gov/arcgis/rest/services
ArcGIS: http://ags10.dot.illinois.gov/ArcGIS/rest/services
ArcGIS: http://gisweb.iema.state.il.us/ArcGIS/rest/services

Indiana
ArcGIS: http://maps.indiana.edu/arcgis/rest/services
ArcGIS: https://gis.in.gov/arcgis/rest/services
ArcGIS: http://imagery.in.gov/arcgis/rest/services
ArcGIS: http://egislb-1921188874.us-east-1.elb.amazonaws.com/arcgis/rest/services

Iowa
ArcGIS: https://programs.iowadnr.gov/geospatial/rest/services
ArcGIS: https://geonexusr.iowadot.gov/ArcGIS/rest/services

Iowa State University: http://mesonet.agron.iastate.edu/ogc/

Kansas
ArcGIS: http://mapserver.kansasgis.org/arcgis/rest/services
ArcGIS: http://imageserver.kansasgis.org/arcgis/rest/services
ArcGIS: http://services.kansasgis.org/arcgis/rest/services
ArcGIS: http://wfs.ksdot.org/arcgis_web_adaptor/rest/services

Kentucky
ArcGIS: http://kygisserver.ky.gov/arcgis/rest/services
ArcGIS: http://maps.kytc.ky.gov/arcgis/rest/services
ArcGIS: http://kgs.uky.edu/arcgis/rest/services

Louisiana
No state government GIS server found yet. Do you know of any?

Maine
ArcGIS: http://arcgisserver.maine.gov/arcgis/rest/services
ArcGIS: http://ummgis.umm.maine.edu:6080/arcgis/rest/services

Maryland    Go to the Gmap4 GIS maps for Maryland
ArcGIS: http://geodata.md.gov/imap/rest/services
ArcGIS: http://maps.roads.maryland.gov/ArcGIS/rest/services
ArcGIS: http://geodata.md.gov/appdata/rest/services
ArcGIS: http://imagery.geodata.md.gov/imap/rest/services

Massachusetts
ArcGIS: http://gisprpxy.itd.state.ma.us/arcgisserver/rest/services
ArcGIS: http://services.massdot.state.ma.us/ArcGIS/rest/services
ArcGIS: http://maps.env.state.ma.us/arcgis/rest/services
ArcGIS: http://gis-services.capecodcommission.org/arcgis/rest/services
ArcGIS: http://tiles1.arcgis.com/tiles/hGdibHYSPO59RG1h/arcgis/rest/services

Michigan    Go to the Gmap4 GIS maps for Michigan
ArcGIS: http://gisago.mcgi.state.mi.us/arcgis/rest/services

Minnesota    Go to the Gmap4 GIS maps for Minnesota
ArcGIS: http://arcgis.dnr.state.mn.us/arcgis/rest/services
ArcGIS: http://gisservices.dot.state.mn.us/ArcGIS/rest/services
ArcGIS: http://pca-gis02.pca.state.mn.us/arcgis/rest/services
ArcGIS: http://w20.education.state.mn.us/arcgis/rest/services
ArcGIS: http://gis.mda.state.mn.us/arcgis/rest/services
ArcGIS: http://gis2.metc.state.mn.us/arcgis/rest/services
ArcGIS: http://geoserver.state.mn.us/arcgis/rest/services
WMS: http://geoint.lmic.state.mn.us/cgi-bin/wmsll?VERSION=1.3.0&SERVICE=WMS&REQUEST=GetCapabilities
WMS: http://mngeo.state.mn.us/chouse/wms/wms_image_server_specs.html

Mississippi
ArcGIS: http://gis.ms.gov/arcgis/rest/services
ArcGIS: http://gisonline.ms.gov/ArcGIS/rest/services
ArcGIS: http://gis.deq.ms.gov/ArcGIS/rest/services
ArcGIS: http://arcgis.gomdot.com/MDOTArcGIS10/rest/services/external

Missouri
ArcGIS: http://egis.mdc.mo.gov/arcgis/rest/services
ArcGIS: https://emgis.oa.mo.gov/arcgis/rest/services
ArcGIS: https://ogitest.oa.mo.gov/arcgis/rest/services
ArcGIS: http://msdisweb-nn.col.missouri.edu:6080/arcgis/rest/services
ArcGIS: http://moimagery.missouri.edu/ArcGIS/rest/services

Montana
ArcGIS: http://gisservicemt.gov/arcgis
ArcGIS: http://gis.fwp.mt.gov/arcgis101/rest/services
ArcGIS: https://app.mdt.mt.gov/arcgis/rest/services

Nebraska
ArcGIS: http://maps.outdoornebraska.gov/arcgis/rest/services
ArcGIS: https://prodmaps.ne.gov/public/rest/services

Nevada
ArcGIS: http://ndep-emap.nv.gov/ArcGIS/rest/services
ArcGIS: http://gis.ndow.nv.gov/arcgis/rest/services
ArcGIS: http://gis.rtcsnv.com/arcgis/rest/services

New Hampshire
ArcGIS: http://xml2.des.state.nh.us/arcgis/rest/services
ArcGIS: http://sps01.nh.gov/ArcGIS/rest/services

New Jersey
ArcGIS: http://gis.njtpa.org/arcgis/rest/services
ArcGIS: http://geodata.state.nj.us/arcgis/rest/services
ArcGIS: http://njgin.state.nj.us/ArcGIS/rest/services

New Mexico
ArcGIS: http://nmbbmapping.org/arcgis/rest/services
ArcGIS: http://x-23-q.env.state.nm.us:6080/arcgis/rest/services

New York    Go to the Gmap4 GIS maps for New York
ArcGIS: http://orthos.dhses.ny.gov/ArcGIS/rest/services
ArcGIS: http://gis3.dot.ny.gov/arcgis/rest/services
ArcGIS: http://gis.dot.ny.gov/ArcGIS/rest/services
ArcGIS: http://gisservices.dhses.ny.gov/arcgis/rest/services
ArcGIS: http://spatialwebhost.com/ArcGIS/rest/services

North Carolina
ArcGIS: http://accessnc.commerce.state.nc.us/arcgis/rest/services
ArcGIS: https://gis11.services.ncdot.gov/arcgis/rest/services
ArcGIS: http://services.nconemap.com/arcgis/rest/services
ArcGIS: http://tiles1.arcgis.com/tiles/YfqBAUM5nWR3yhGP/arcgis/rest/services
ArcGIS: http://gis.ncdcr.gov/ArcGIS/rest/services

North Dakota
ArcGIS: http://ndgishub.nd.gov/arcgis/rest/services
ArcGIS: http://gis.dot.nd.gov/arcgis/rest/services/external

Ohio
ArcGIS: https://gis.ohiodnr.gov/ArcGIS/rest/services
ArcGIS: http://gis5.oit.ohio.gov/ArcGIS/rest/services
ArcGIS: https://geo.oit.ohio.gov/arcgis/rest/services
ArcGIS: http://epagis1.oit.ohio.gov/arcgis/rest/services
ArcGIS: http://odotgis.dot.state.oh.us/arcgis/rest/services

Oklahoma
ArcGIS: http://gis.deq.ok.gov/ArcGIS/rest/services
ArcGIS: http://rest.owrb.ok.gov/ArcGIS/rest/services

Oregon    Go to the Gmap4 GIS maps for Oregon
ArcGIS: http://navigator.state.or.us/ArcGIS/rest/services
ArcGIS: https://maps.prd.state.or.us/arcgis/rest/services
ArcGIS: https://gis.odot.state.or.us/ArcGIS/rest/services
ArcGIS: http://deqgisweb.deq.state.or.us/ArcGIS/rest/services
ArcGIS: http://summit.wrd.state.or.us/arcgis/rest/services
ArcGIS: https://gartrellgroup.net/arcgis/rest/services/odfw
ArcGIS: http://chetco-new.dsl.state.or.us/ArcGIS/rest/services

Pennsylvania
ArcGIS: http://fbweb.pa.gov/arcgis/rest/services
ArcGIS: https://pdargissvr.pa.gov/ArcGIS/rest/services
ArcGIS: http://gis.dcnr.state.pa.us/agsprod/rest/services
ArcGIS: http://data1.commons.psu.edu/ArcGIS/rest/services/pasda/PennsylvaniaGameCommission/MapServer
ArcGIS: http://data1.commons.psu.edu/ArcGIS/rest/services/pasda/PennDOT/MapServer

Rhode Island
ArcGIS: https://beaches.health.ri.gov/arcgis/rest/services
ArcGIS: https://welltesting.health.ri.gov/arcgis/rest/services

South Carolina
ArcGIS: http://gisweb01vm.dhec.sc.gov/arcgis/rest/services
ArcGIS: https://ags2.scgov.net/arcgis/rest/services

South Dakota
ArcGIS: http://arcgis.sd.gov/arcgis/rest/services

Tennessee
ArcGIS: http://tnmap.tn.gov/arcgis/rest/services
ArcGIS: https://gis.tnema.org/ArcGIS/rest/services

Texas
ArcGIS: http://tpwd.state.tx.us/arcgis/rest/services
ArcGIS: http://wwwgisp.rrc.state.tx.us/arcgis/rest/services
ArcGIS: https://maps.dot.state.tx.us/arcgis/rest/services
ArcGIS: http://vector.tnris.org/arcgis/rest/services

Utah    Go to the Gmap4 GIS maps for Utah
ArcGIS: http://mapserv.utah.gov/arcgis/rest/services
ArcGIS: http://tlamap.trustlands.utah.gov/arcgis/rest/services
ArcGIS: http://maps.udot.utah.gov/arcgis/rest/services
ArcGIS: http://maps.geology.utah.gov/arcgis/rest/services
ArcGIS: http://gis.waterrights.utah.gov/ArcGIS/rest/services

Vermont
ArcGIS: http://vtransmap01.aot.state.vt.us/arcgis/rest/services
ArcGIS: http://anrmaps.vermont.gov/arcgis/rest/services
ArcGIS: http://maps.vcgi.org/arcgis/rest/services

Virginia
ArcGIS: http://gismaps.vita.virginia.gov/arcgis/rest/services
ArcGIS: https://fwisweb1.dgif.virginia.gov/arcgis/rest/services
ArcGIS: http://dswcapps.dcr.virginia.gov/arcgis/rest/services
ArcGIS: https://arcgis.vdem.virginia.gov/arcgis/rest/services
ArcGIS: http://gis.vdot.virginia.gov/arcgis/rest/services

Washington    Go to the Gmap4 GIS maps for Washington
ArcGIS: https://fortress.wa.gov/dnr/arcgis102/arcgis/rest/services
ArcGIS: https://fortress.wa.gov/ecy/ecyprodgislb/arcgis/rest/services
ArcGIS: http://gispublic.dfw.wa.gov/arcgis/rest/services
ArcGIS: https://geodataservices.wdfw.wa.gov/arcgis/rest/services
ArcGIS: http://wsdot.wa.gov/ArcGIS/rest/services
ArcGIS: http://wsdot.wa.gov/geosvcs/ArcGIS/rest/services
ArcGIS: http://webgis3.dor.wa.gov/ArcGIS/rest/services
ArcGIS: http://gismanager.rco.wa.gov/ArcGIS/rest/services
ArcGIS: http://services.arcgis.com/jsIt88o09Q0r1j8h/ArcGIS/rest/services

West Virginia
ArcGIS: http://services.wvgis.wvu.edu/ArcGIS/rest/services
ArcGIS: http://gis.wvdot.com/arcgis/rest/services
ArcGIS: http://tagis.dep.wv.gov/arcgis/rest/services

Wisconsin    Go to the Gmap4 GIS maps for Wisconsin
ArcGIS: http://dnrmaps.wi.gov/arcgis/rest/services
ArcGIS: http://datcpgis.wi.gov/arcgis/rest/services
ArcGIS: http://uadnrmaps.wi.gov/arcgis/rest/services

Wyoming
ArcGIS: http://wygiscservices.wygisc.org/arcgis/rest/services
ArcGIS: http://wogccms.state.wy.us/arcgis/rest/services


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USA other sources for GIS data

The sections ArcGIS REST metadata and WMS metadata explain how to use these links. If you have not yet read those sections, then now would be a good time to do so.

BP Deepwater Horizon well oil spill
Links to meta data: http://gis.aerometric.net/services.htm
Homepage: http://gis.aerometric.net/

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Canada sources for GIS data

The sections ArcGIS REST metadata and WMS metadata explain how to use these links. If you have not yet read those sections, then now would be a good time to do so.

Geobase
WMS Metadata: http://ows.geobase.ca/wms/geobase_en?service=wms&request=GetCapabilities&version=1.1.1
Data descriptions - scroll down: http://geobase.ca/geobase/en/wms/index.html
Geobase homepage: http://geobase.ca/geobase/en/

Fish and ocean
http://pac.dfo-mpo.gc.ca/gis-sig/services-eng.htm

British Columbia
ArcGIS: http://maps.gov.bc.ca/arcgis/rest/services

Ontario

ArcGIS: http://giscoeservices.lrc.gov.on.ca/ArcGIS/rest/services

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Australia source for GIS data

The section WMS metadata explains how to use this link. If you have not yet read that section, then now would be a good time to do so.

A variety of data including contour lines and shading
Metadata: http://ga.gov.au/gis/services/topography/Australian_Topography/MapServer/WMSServer?request=GetCapabilities&service=WMS


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How to Google search for ArcGIS data

The GIS servers listed above were mostly found with google searches. After all, the index pages on GIS servers are simple web pages that can be found if you know the right search terms to use.

All GIS index web pages include "rest/services" in their link. Therefore you should include that phrase with the quotes in your search string. For example, to search for GIS servers with Florida data you could do a Google search on:
     Florida "rest/services"

Here is a Florida GIS link your search might find:
http://gis.doh.state.fl.us/ArcGIS/rest/services/CensusTract2010/MapServer

Open the above link and note that the upper left corner says "ArcGIS Services Directory". Click on the word "Home" just under that heading. You are now at the top of the GIS index pages for this server. Look down on the 'Home' page just a bit and you will see the headings "Folders" and/or "Services". The links in both of those sections will lead to individual GIS basemaps or overlays that Gmap4 can display.

Look under the "Folders" heading and click on "WalkingPaths".
Then under the "Services" heading, click "WalkingPaths/WalkingPaths".

Near the top of the page you should now see the heading "WalkingPaths/WalkingPaths (MapServer)" and you see a list of 5 layers numbered 0 through 4.

To display the "Restaurant Walk (3)"layer you would make a rest parameter like so:
&rest=http://gis.doh.state.fl.us/ArcGIS/rest/services/WalkingPaths/WalkingPaths/MapServer?name=Restaurant_walk&layers=3&transparent=true

Remember Gmap4 can display any MapServer and ImageServer data. It cannot presently display FeatureServer data or any other type of data that you might find on an ArcGIS server.

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Part 5 - Example Gmap4 links

In order for Gmap4 to let you 'click link - see GIS data', the links need to be longer than average. Don't panic. Each of these links can be divided into the following pieces:

1. Gmap4 program code
https://mappingsupport.com/p/gmap4.php

2. All Gmap4 parameters except any '&q=', '&markers=', '&rest', '&wms=' parameters
Although the following three parameters are optional, you will likely want to use them when displaying GIS data:
&ll= latitude,longitude for map center
&z= zoom level when map opens
&t= map type (comma separated list). One basemap name (optional) and one or more transparent overlay names.

3. '&markers=' parameter or '&q=' parameter (optional)
The '&markers=' parameter is part of Gmap4's unique map-in-a-link feature and it can be used to put a title on these maps and also used to display multiple KML/KMZ files. Since a map title can include one or more links, sometimes a map title will take up a good part of a Gmap4 link.

4. '&rest=' and or '&wms=' parameters (often more than one)
Each one identifies one GIS server and one or more layers of data hosted on that server.

All '&rest' and '&wms=' parameters need to be at the end of the Gmap4 link.

If the link includes a '&markers=' parameter or '&q=' parameter then it must come right before the first '&rest=' or '&wms=' parameter.

You might also see "%20" in some Gmap4 links. This is one form of computer-speak for a space. Some forum software does not correctly handle links with spaces. Some email software is the same way. By changing each space to "%20" this problem is avoided.

Moral of the story: Don't be spooked by these long links. Simply divide them into pieces as shown above and you will see what is going on.

Example Gmap4 links showing GIS data - USA

Tip for smartphone and tablet users. To save any Gmap4 link as a bookmark in the browser on your smartphone or tablet, email that link to yourself. Then open that link with your mobile browser and save it as a bookmark.

Recreation maps with GIS layers

Each state has a vast amount of recreation data on GIS (Geographical Information System) servers. Whether you want to know about public land boundaries, trails, campgrounds, boat launches, hunting areas, etc, your state likely has a GIS data layer that has that information. This new project will go state-by-state to find those data layers and make Gmap4 links so you can see that GIS recreation data with Gmap4.

Visit the homepage for the GIS recreation maps

USA basemap - two versions

This map has two additional basemaps that are added via "&rest=" parameters. When the map opens it shows most of the USA (on a desktop size screen) and has a background that is shaded to help show elevation changes. The other new basemap is the same except the background shows aerial photos. The data for both of these basemaps is already stored as tiles on the GIS server. This means that the maps display quickly. However, these pre-made tiles are only designed to be displayed at a maximum zoom of 15 (Google scale shows 200m/1000ft). If you zoom in further then the data becomes fuzzy.

This is similar to the "US Topo" product that the USGS is using to replace the traditional paper 1:24,000 scale topographic maps.

https://mappingsupport.com/p/gmap4.php?ll=38.539036,-99.11745&z=5&t=USA_basemap_shaded&coord=off&rest=http://basemap.nationalmap.gov/ArcGIS/rest/services/USGSTopo/MapServer?name=USA_basemap_shaded&layers=0&transparent=false&rest=http://basemap.nationalmap.gov/ArcGIS/rest/services/USGSImageryTopo/MapServer?name=USA_basemap_aerial&layers=0&transparent=false

Boundary Water Canoe Area, Minnesota

This map shows the boundary (GIS data), entry points (KML file #1), portages (KMl file #2) and campsites (txt file) that are open as of June 2013. Click a campsite symbol for the coordinates. You can also zoom in and then click Menu == > Label On/Off. A label holding the coordinates will appear next to each campsite. If you zoom in a bunch then you will see lines and arrows showing the direction the water is flowing (this data looks real nice on the "t4 Topo High" basemap). When the map opens, color infrared aerials are displayed. You can display "1-foot" aerials that have better resolution that Google's aerials. Anything that looks like a space in the link is actually an underline character.

Note: The GIS layers for this map are specified in the 'txt' file that you see in the link. You can download that txt file and look at its contents.

https://mappingsupport.com/p/gmap4.php?t=Color_infrared,Water_flow_direction,Boundary&q=https://sites.google.com/site/gmap4files/p/recreation/bwca_campsites.txt

Detailed boundary for land owned by the USA

This example shows very detailed boundary lines for most of the federally owned land in the USA. This includes national forest land, Bureau of Land Management holdings and other land. This map opens centered near Denver but can display data for all of the USA.

https://mappingsupport.com/p/gmap4.php?ll=39.740986,-104.996338&t=h,Public_land&z=8&wms=http://wildfire.cr.usgs.gov/ArcGIS/services/geomac_dyn/MapServer/WMSServer?name=Public_land&layers=1&transparent=true

Wildland Fires

March 2015 update: The link for the Gmap4 wildland fire map is only going to be published as part of the recreation mapping project mentioned above. Doing this will make it easier to include new fire-related GIS data layers as they become available. Watch for changes in the weather layers of the Gmap4 fire map around May-June when NOAA is expected to put into production updated GIS server technology.

Earthquake risk

The colors on this map show the relative amount of risk for an earthquake. If you zoom in on this map then you will see the county boundaries. If you zoom in two more steps then you will see the county names.
This GIS server can be busy so it may take 10-20 seconds for some of the data to appear on the map.

The "&markers=" parameter is used to put a title on the map. The title includes a link to a png file that displays a map legend.

https://mappingsupport.com/p/gmap4.php?ll=38.121103,-99.583985&z=5&t=US_Seismic_hazard,Counties,States&markers=||title=<b>US%20Seismic%20Hazard<br%20/><a%20href=http://geodata.epa.gov/arcgis/rest/services/Region9/R9HomeViewGeology/MapServer/legend%20target='_blank'>Legend</a></b>&rest=http://geodata.epa.gov/arcgis/rest/services/Region9/R9HomeViewGeology/MapServer?name=US_Seismic_hazard&layers=6&transparent=true&rest=http://services.nationalmap.gov/ArcGIS/rest/services/govunits/MapServer?name=Counties&layers=3,13&transparent=true&rest=http://services.nationalmap.gov/ArcGIS/rest/services/govunits/MapServer?name=States&layers=17,18&transparent=true

USA coastal charts

This map can display all of the USA costal nautical charts prepared by NOAA. According to NOAA, these electronic charts will be updated once every two weeks and are not to be used for navigation. Now would also be a good time for you to review Gmap4's terms of service. In other words, if you put your boat on the rocks, don't blame NOAA and don't blame me.

When this map opens it shows a detailed chart for the mouth of the Columbia River between Oregon and Washington. Be patient. Some 'tiles' have a lot of detail and it may take a few seconds for all the data to appear on your screen.

https://mappingsupport.com/p/gmap4.php?ll=46.257257,-124.043198&z=14&t=NOAA_nautical_charts&rest=https://seamlessrnc.nauticalcharts.noaa.gov/arcgis/rest/services/RNC/NOAA_RNC/MapServer?name=NOAA_nautical_charts&layers=3&transparent=false

Of course all the Gmap4 features continue to work when GIS data is being displayed. Would you like to display a UTM grid on top of the chart? No problem. Use the Menu button to turn on UTM. Want to find a certain location? Try Menu ==> Search. When you are in an area covered by these charts and there is cell coverage, try opening this coastal chart link with the browser in your smartphone or tablet and then touch Menu ==> My location. (Be sure the GPS in your smartphone or tablet is turned 'on'.)

To display your GPS track on the chart first put a GPX or KML file online. Google Sites provides free hosting. Copy the following Gmap4 link and replace the underline with the http link to your GPX file.

https://mappingsupport.com/p/gmap4.php?t=NOAA_nautical_charts&q=______________&rest=https://seamlessrnc.nauticalcharts.noaa.gov/arcgis/rest/services/RNC/NOAA_RNC/MapServer?name=NOAA_nautical_charts&layers=3&transparent=false

Now paste the completed link into a browser. When the map opens it will aultomatically be zoomed and centered so all of your GPX data is on the screen.

Index to USGS topographic maps

The following link shows the topo map index for the Sierra Nevada mountains in California near Lake Tahoe.

https://mappingsupport.com/p/gmap4.php?ll=39.068781,-120.226135&z=10&t=m,Topo_index_1:24000&rest=http://services.nationalmap.gov/arcgis/rest/services/map_indices/MapServer?name=Topo_index_1:24000&layers=10,4&transparent=true

Opps! Whoever built this data used a poor font for the map names. If you have trouble reading the names, then change the basemap to "all white basemap".

Q: How can this map help you?
A: Assume you are planning a hiking trip and want to take paper topographic maps along. Turn off the map index so it is not distracting. Click Menu ==> Draw and Save. Click Continue. Click along the trail you plan to hike. Turn the map index back on. Change the base map to "All white basemap". You can now easily read the names of the topographic maps that cover the area where you will be hiking.

If you want the map to open and automatically show the index for a certain area, simply make the map look the way you want it to look on your screen and then click Menu ==> Link to this map. The link you see will reproduce the map you see on your screen.

US Army Corps of Engineers

This map shows some defense related land that involves the US Army Corps of Engineers. Click an area to see its name.

https://mappingsupport.com/p/gmap4.php?ll=37.398715,-99.033123&z=5&t=m,USACE_defense_site_bdry&rest=http://rsc-agisu.usace.army.mil/s1arcgis/rest/services/National_Admin/Defense_Site_Locations/MapServer?name=USACE_defense_site_bdry&layers=1&transparent=true

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Example Gmap4 links showing GIS data - Canada

British Columbia Forest Service Roads

To see the road labels better, change the basemap to the Google road map or the "All white basemap". Click a road to see all the GIS attributes for the thing that you clicked.

https://mappingsupport.com/p/gmap4.php?ll=49.319793,-121.792245&z=13&t=h,Forest_service_road&rest=http://maps.gov.bc.ca/arcgis/rest/services/eteam/eteam/MapServer?name=Forest_service_road&layers=52&transparent=true

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