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Tip: Search topographic maps using cooordinates

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I suspect that benchmark hunters sometimes have a set of coordinates and they would like to see that spot on the best map available. If you have any type of coordinates (DMS, DM, D) then this tip shows how you can display that spot on a detailed topographic map. The link below will open a map of the USA. Click Menu==>Search. Enter your coordinates using any reasonable latitude/longitude format and click Search+Mark. To see the detailed topographic map, click Terrain==>MyTopo.


USA map: http://www.mappingsupport.com/p/gmap4.php?ll=39.658774,-96.561542&t=t1&z=4


The map is presented by Gmap4 which is a 100% free enhanced Google Map viewer. The Gmap4 homepage has examples, a change log and detailed Help file:


Gmap4 homepage: http://www.mappingsupport.com/p/gmap4.html



Joseph Elfelt - Gmap4 author

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Nice work, Joseph!


One small suggestion - the bullseye cursor (or whatever you call it) that stays at the center of the map sometimes disappears as it blends into dark colors underneath. You might consider a user option to change color, possibly to toggle it to white or yellow, or perhaps offer more options than than.


A small quibble on an excellent project. Thanks for doing it!



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Thanks for the kind words and suggestion.

I always welcome ideas for enhancements and have added yours to the list.


Meanwhile, I just recently added the current magnetic declination to each map. In order to display that info Gmap4 uses software from http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html

combined with data from


Thanks to NOAA staffer Manoj C. Nair for pointing me in the right direction.


Magnetic declination is always changing. If you compare the Gmap4 value to the declination stated on any printed map, then you may be surprised to discover how out-of-date the map value has become. For example, the 1965 topographic map for Stevens Pass, WA states that the declination is 22 degrees. However, the current declination is 16 degrees 36 minutes as seen here:



Remember, if you are facing due north and the declination is positive, then magnetic north is to your right. Conversely, if you are facing due north and the declination is negative, then magnetic north is to your left.

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Gmap4 has been updated to version 1.9.1 dated January 17, 2011. This version adds support for UTM coordinate grids. All UTM support in Gmap4 uses the WGS84 datum. This UTM support works worldwide. For more info on UTM coordinates see: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system

(Pay back time: When you visit other outdoor-related forums, please do a search and see if Gmap4 has been mentioned. If not, it would just take a moment for you to pass the word along. Also, are you doing the social network thing? Consider saying something nice about Gmap4.)


Here’s a map of Grand Canyon Village with a UTM grid.



To toggle UTM support on and off, click Menu ==> UTM On/Off. If UTM is ‘on’ then Gmap4 gives you UTM information in three ways:


1. A UTM grid is displayed. This UTM grid is displayed on both the MyTopo topographic maps (USA and Canada) and the standard views (aerial, etc) provided by Google Maps.


2. The lower right corner of the screen will always show the UTM zone and UTM coordinates for both the cursor and map center.


3. You can get the UTM zone and coordinates for any point on the map by right-clicking that point.

Things to keep in mind


You can build you own map links by using URL parameters. If you want your map to appear on the user’s screen and already have UTM turned on, then add this URL parameter: &coord=utm


Here is a comparison:

With UTM on


With UTM off (default)



If you zoom out far enough then you will not see a UTM grid. Instead you will only see vertical red lines which mark the edges of the UTM zones.


UTM grid lines that are near the edge of their zone often appear curved when displayed using the map projection used by Google Maps. The grid lines in the adjoining zone will curve in the opposite direction. For example, the next map is centered near Lake Tahoe. The red line marks the edge of adjoining UTM zones. Double click each side of the red line (this changes the map center) and watch the UTM grid lines change. The grid lines are calculated based on the UTM zone that contains the center of the map.



Some MyTopo topographic maps already have a UTM grid printed on them. Caution! Some of those printed grids are based on the older datum NAD27. Those older grids will have a uniform offset from the grid displayed by Gmap4 which is based on datum WGS84 . For example: Here is a map showing part of the Alpine Lakes Wilderness area in Washington State where the MyTopo maps have a UTM grid based on the WGS84 datum. Click Menu ==> UTM On/Off and you will see the faint UTM grid printed on the map:



By contrast, here is a map showing part of the Yosemite Valley area in California, where the MyTopo maps have a UTM grid based on NAD27. Note the uniform offset between the two sets of grid lines.



Usually (but not always) the different zoom levels use a different scale for the UTM grid. To learn the grid scale, compare the cursor coordinates (lower right corner) as you point to adjacent grid lines. If you want to know the zoom level, right click the map.


Maps with UTM grid lines can be printed. File ==> Print Preview


If you know of any other map viewing software that can display the MyTopo topographic maps along with a UTM grid, I would enjoy knowing about it.


Future UTM improvements


There are different methods for putting labels on the grid lines. I am pondering what will work best.

Another possible improvement is to let the user change the line width, color and/or spacing.

Other ideas?


Next Gmap4 update


Bad news: The ‘Search’ feature of Gmap4 no longer works very well for placenames. This feature uses Google’s ‘geocoding’ service on the backend. OK, I admit it. Gmap4 was pushing the envelope in its use of that service. Whoops - Google pushed back. Guess who won? I will add a second search tool that is designed to work well with placenames.


Good news: The existing ‘Search’ feature of Gmap4 still works fine for searching on (1) anything related to addresses including names of many settlements that no longer exist and (2) any reasonable way to write a latitude/longitude pair.


Finally, if you find Gmap4 to be useful I hope you can take a moment and do some ‘pay-back’ by letting other people know about it.



Joseph - Gmap4 author

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I just promoted Gmap4 from version 1 to version 2.


Little reason: I added support for viewing the set of topo maps that used to be known as Terraserver and now are known as Microsoft Research Maps. Click the map type button in the far upper right and select “US Topo”. You can really see the quality difference compared to the MyTopo maps.


The US Topo maps often load a bit slow. Part of the reason is that each map tile must be re-projected on-the-fly in order to match the map projection used by Google Maps. I added support for these maps in case they show old (abandoned?) trails that are not on the MyTopo maps.


Big reason: This update introduces a new text file format that makes it super easy to produce maps. For a quick look, scroll down a bit on the Examples page: http://www.mappingsupport.com/p/gmap4_examples.html


This new file format is so easy that middle school students can quickly learn how to produce maps.


Maps can include:

* Many different kinds of symbols (i.e. markers/icons)

* Lines of any color and any width

* Balloons that appear when symbols are clicked

* Links in the balloons

* Clickable photo thumbnails in the balloons

* And more


Did I mention that this is truly easy?


For the details, you can search the Help file on ‘delimited’. Or just go to page 32 in the 5-6-2011 version of the Help file. http://www.mappingsupport.com/p/gmap4_help.pdf


Homepage: http://www.mappingsupport.com/p/gmap4.html





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Joseph, I just played around a little with your mapping program this evening. Your help file about using google sites for placing files free on the internet, was excellent and extremely easy to walk thru. I didn't have any idea that google had that.


I used GSAK to help me sort thru some benchmarks I have found, then exported this file in a gpx file. I then uploaded this gpx file to google sites (per your instructions), and here are my results. I will really learn more about your maps when I have more time, but I see a lot of uses for it. Thanks for sharing with us



Edited by LSUFan
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Thanks for the kind words.

I looked at your map - you've been busy!

Also, I clicked a marker and noticed that the long text blew past the bottom of the balloon. I wish I could do something about that but alas I cannot. The max size of the balloon is determined by Google and they have not provided for a scroll bar.


And since you are an LSU sorta person, check out this flood related map. Click the "i" symbol near the upper middle for some fascinating background (which you likely already know).

To turn the symbol labels on/off click Menu ==> Labels On/Off.


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Click the "i" symbol near the upper middle for some fascinating background (which you likely already know).

To turn the symbol labels on/off click Menu ==> Labels On/Off.



That is extremely interesting, and I didn't know that. Thanks for sharing. Everyone is on high alert near the River. They are saying we are going to get higher water than even in the 1920's record floods. Our governor has been flying around a lot. It's going to be nailbiter, hoping the levees hold.


I do know some history of the MS River closer to home, being an amateur local Civil War buff. During the Union Army siege of Vicksburg, there were several attempts to dig canals off of the MS River, and thus allow the navy ships to bypass the guns of Vicksburg, and effectively cut off it strategic importance. These attempts failed...........but in the 1870's, the MS River altered it's course naturally....thus bypassing Vicksburg after all. :o


You can go to your map link, and follow it up north to Vicksburg and see where the MS River now leaves the main part of Vicksburg out of it's path.



Edited by LSUFan
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I just promoted Gmap4 version 2.1.4 from testing into production. Some of the new features are described below. For a full list of the changes in this version please see http://www.mappingsupport.com/p/gmap4_whats_new.html


Remember, Gmap4 lives in the cloud and does not require you to download or install anything. Anytime you view a map with Gmap4, you automatically will be using the most recent version.


The big news is that you can now strap on a personal jet pack and fly around in 3D anywhere in the world. (The Gmap4 ‘Search’ feature is a useful way to zip you to the spot where you wish to begin flying.)


You can fly at low altitude over any map that has a GPS track and see the world in 3D. No sweat, no bug bites, no blisters.


All you have to do is download the Gmap4 ‘Help’ pdf file dated September 12, 2011 or more recent and search for ‘Tips for flying’. Anyone can quicky and easily learn to fly with just a mouse by taking a quick trip through flight school by reading those tips. Those tips will show you how to fly over the John Muir Trail in California starting from the summit of Mt. Whitney.


Gmap4 ‘Help’ file: http://www.mappingsupport.com/p/gmap4_help.pdf


In addition, the ‘directions’ feature has been re-written. Right-click the map and then click either ‘Direction from here’ or ‘Direction to here’. After the route appears, you can drag it to make changes. You can build a Gmap4 URL that will open with the directions panel displayed and the destination filled in. This will be useful for helping people obtain directions to a meeting spot. Search the Gmap4 Help file for ‘Tips for using directions’.


Also, information on how to donate has been added to the ‘Action’ menu and the Gmap4 website.



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After the September 12th update to Gmap4 I heard from a handful of people that this new version gave them a blank screen and nothing else. For most people the new version worked fine but for an unfortunate few it did not. I want to thank those that spoke up. After all, when things work fine for me, I have no way of knowing that they do not work fine for you unless you tell me. The best way to reach me is to e-mail through my contact page: http://www.mappingsupport.com/p/gmap4_contact.html


Late today I updated the Gmap4 code. If you click Menu ==> About then you will see the date September 14, 2011 (or later).


If you are still having trouble viewing maps with Gmap4, then I have a favor to ask. In addition to updating the code I also put together a short list of easy things that you can try to get the latest version of Gmap4 working on your system. Here’s the favor: Please download the latest copy (dated September 14, 2011) of the ‘Help’ file (http://www.mappingsupport.com/p/gmap4_help.pdf) and search that file for ‘tips on flying’. Near the end of that section you will see a heading that starts “Background...”. That section gives you a peek under the hood and suggests several easy/quick things you can do to try and get the current version of Gmap4 working on your system.


Some of those suggestions have worked for others, so I hope if you are having problems that you take a few minutes and give them a try. And if nothing else works, then the last suggestion gives you a link to the prior version of Gmap4 which does not include the new ‘Earth’ feature which seems to be the source of most of the problems.


But since being able to fly over your GPS track (or any other data file) in 3D is easily the coolest feature in Gmap4, I most certainly hope you are able to convince your system to run the current version of Gmap4 so you can waste as much time as I have flying here and there. It’s addictive but - hey - you’ve been warned.

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Gmap4 has been updated to version 2.1.6 dated September 17, 2011.

Homepage: http://www.mappingsupport.com/p/gmap4.html


Reminder: Since Gmap4 lives in the cloud (1) you never have to download or install Gmap4 and (2) you are always automatically using the latest version of the code. But if Gmap4 does not seem to work then please clear your browser’s cache and try again. To see the Gmap4 version number you can click Menu ==> About on any map.


This update fixes the ‘blank screen’ problem that some users experienced after the September 12th update. If you experienced that problem, then please try Gmap4 again.

In order to use the new 3D ‘Earth’ view, your computer system needs to have the Google Earth browser plug-in installed. The Gmap4 code now checks to see if your system already has this plug-in installed. If your computer system does not have this plug-in installed, then you will see a message telling you that and a link to Google where you can download the plug-in if you decide to install it. If you decide to install the plug-in, please follow the instructions in that message. You need a broadband connection and a reasonably modern computer to use the 3D ‘Earth’ view.


Also, your security software might ask you to give permission before this plug-in will work.


If you decide to not install the plug-in, simply close the message window. You can continue using all the other features of Gmap4 except the ‘Earth’ view.

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Gmap4 has been updated to version 2.2. The full list of changes is posted on the Gmap4 “what's new” page (see hompage link below). Here are some highlights.


First, Gmap4 can add labels to Google maps. The labels are built from the waypoint names in your file. Your existing maps will work with this feature, except KMZ files are not yet supported. Labels can be styled with your own HTML and CSS. The following link displays a GPX file that is hosted at Topofusion and displays with labels turned on. http://www.mappingsupport.com/p/gmap4.php?q=http://www.topofusion.com/GPX/BrianHead-Network.gpx&t=t2&label=on


To open Gmap4 with labels turned on, include this parameter in your Gmap4 URL: &label=on

To toggle the labels after a map is displayed click Menu ==> Label On/Off


You can style the labels with your own HTML and CSS. This label feature works with all the file formats that Gmap4 can read except KMZ files. Label support for KMZ files will be added in a future update.


Below is an example of a map I made with fancy labels. Note that (1) each label is clickable and (2) when you shift to an aerial map view then the labels acquire a solid background so the text does not disappear in shadows on the aerials. This map uses a delimited text file that is hosted at Google Sites.



Second, a number of features have been added to the delimited text file format that Gmap4 can display. The section of the Gmap4 Help file titled “Delimited text files - Some details” has been completely re-written and now starts with a series of example maps that will let you rapidly learn the basics. If you want the most control over your map, this is the file format to use.


Third, the internet security features of Gmap4 have been enhanced. If you look at a file that causes Gmap4 to display a security-related message on your screen and you think that message is a ‘false positive’, then please go to the Gmap4 contact page and send an email. Include the URL to the map (Menu ==> Show map URL) in your email.


Fourth, Gmap4 can now display files that include a '?' character in the URL for the file.


For more information please see the Gmap4 homepage: http://www.mappingsupport.com/p/gmap4.html




Joseph, the Gmap4 guy

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The Gmap4 production code is now version 2.3. This is the first version that includes special features for smartphones and other mobile devices.


1. Gmap4 can now find your location on the map. This service will use some or all of:

* Your IP address

* Cell towers

* Wi-fi hotspots

* Any GPS chip in your phone or other mobile device


Simply open any map in your phone’s browser and then select Menu ==> Findme. You can try this right now on your desktop/laptop just to see how it works. However, your desktop/laptop location will likely not be very accurate since in many cases only your IP address will be used.


You can also build Gmap4 URLs that will automatically run the Findme feature when the map opens. Simply include the parameter ‘findme=on’ in the Gmap4 URL.

Example: http://www.mappingsupport.com/p/gmap4.php?findme=on


Since Gmap4 uses the Google maps Application Programming Interface (API), this feature only works if your phone’s browser is online to the internet.


Also, because Gmap4 is a web application, you do not need to download or install anything in order to use Gmap4 on your phone. To open Gmap4 on your phone:

A. Open your phone’s browser. (Remember, that browser has to be online.)

B. Do a web search for Gmap4 - the first hit should be the Gmap4 homepage

C. Select the link just under the homepage title. That link opens Gmap4 and displays a map of the world.

D. Select Menu ==> Findme


Of course you can save the Gmap4 URL as a bookmark in your phone’s browser.


Gmap4 does not save your location or report it to anyone. For more details, please search the Gmap4 Help file on ‘mobile’.



Here are two links with more information if you are curious how this works:




2. You can turn off the coordinates in the lower right corner


Turning off the coordinate display in the lower right will let you see more of the map. You can toggle that display by selecting Menu ==> UTM - LatLng - Off


To open Gmap4 with that display already off, include the parameter ‘&coord=off’ in the Gmap4 URL

Example: http://www.mappingsupport.com/p/gmap4.php?findme=on&coord=off


3. Tweaking the mobile interface

Gmap4 is not a ‘native’ app for your phone. Instead, the exact same code that runs in the browser on your desktop/laptop also runs in the browser on your phone. Amazing! But this means my options for improving the interface when running on a phone are somewhat limited. What I can do fairly easily is add buttons. However, each button would cover part of the map.


Question: Are there any features of Gmap4 important enough that they should have their own buttons? One obvious candidate is the ‘Findme’ feature. Any others?


4. The MyTopo maps now display ads in one corner. That was not my idea!

For example, this map shows part of Yellowstone National Park:



The Trimble Company now owns the MyTopo maps. As the 'price' for being allowed to continue displaying the MyTopo maps at no cost, Gmap4 must display Trimble's ad images when the MyTopo maps are on the screen.


Joseph, the Gmap4 guy

Redmond, WA

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Earlier this year ACMEmapper stopped displaying the medium resolution MYTopo maps and went back to displaying the low resolution Terraserver maps (now called Microsoft Research maps). You can still view the MyTopo maps on Gmap4. You can also view the new higher resolution topo maps.


The Gmap4 code has been updated to version 3.0. There are two new ‘big’ features that many people will find useful.


First, Gmap4 can now display a new set of very high resolution USA topographic maps that (1) are a better quality image than the MyTopo maps, (2) do not have heavy watermarks obscuring part of the map and (3) do not have any ads. The link below displays a basic map of the USA. Zoom in to your favorite area (or use the ‘Search’ feature) then open the menu in the upper right corner and select “t4 Topo High”.



You can also set the amount of hill shading you prefer to see on these new maps. Click Menu ==> Hill shading. And there is a new URL parameter (&hillshade=) you can use to set the hill shading in any Gmap4 URLs that you make.


A developer in California named Matt (http://CalTopo.com) produced these new topo map tiles from data he obtained from the USGS. Matt is paying out of his pocket to host these new map tiles on Amazon’s cloud service. It is my great hope that the Gmap4 user community taken as a whole will be willing to make sufficient donations to pay its share of Matt’s Amazon bill. The Menu button on the map has a ‘donate’ link.


Matt’s high resolution topographic map tiles should cover the states show in green on the following index map. I think the states that are not done yet are FL, LA, MA, MS, NH, RI, SD, VT and WY.


As the USGS finishes high resolution scans (660 pixels per inch) for the remaining states, Matt will be processing that data into tiles.


The Gmap4 ‘Help’ file has more information on these new maps and also instructions for how you can report any problems you discover.


Second, Gmap4 now includes a trip planning feature called “Make a map”. You can now click the map to make waypoints, routes and tracks. You can download your work in a GPX file and then upload that information into many handheld GPS units. Of course you can also put your GPX file online and then make a Gmap4 URL to display your file. This feature works worldwide.


Gmap4’s implementation of this feature lets you:

* Click once and create both a waypoint and routepoint

* Edit any data field (including GPS symbol name) that causes information to appear on your GPS screen


“Make a map” quick start:

1. Zoom in where you want to do trip planning

2. Set the map view you want

3. Click Menu ==> Make a map

4. Click a few spots on the map. Distance in miles and kilometers is reported in the lower right corner.

5. Right click any point

6. Click “Download GPX file”

7. Right click the URL to the GPX file and save it on your harddrive

8. Load the GPX information into your GPS


Each click you just made on the map sets a draggable (click-hold-drag) waypoint and routepoint. This is the Gmap4 default for trip planning.


For more information on these features, please visit the Gmap4 homepage and download the current Help file. The sections that describe these new features are marked “(New)” in the table of contents.

Gamp4 Homepage: http://www.mappingsupport.com/p/gmap4.html


I welcome your suggestions for improvements and any bug reports.




Joseph, the Gmap4 guy

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Recently Gmap4 was updated to version 4.1 and now includes a unique map-in-a-link feature that is worth mentioning. Anyone can now make a custom map and save their data right in a Gmap4 link. You do not need to save your data in a separate file such as a GPX or KML file. This may be the easiest and faster way for you to make a custom online topographic map.


To try out this feature:

1. Click Menu ==> Draw and Save

2. Click the map a few times to set draggable symbols and draw a line

3. Rightclick any symbol and select “Gmap4 display long link”


You can copy the link that is displayed, paste it into a new browser address bar, hit enter and your custom map will be displayed.


This feature also works on your iPhone, iPad, android and other mobile device. Remember, Gmap4 is a browser app and your browser has to be online. After you tap the screen to set some draggable symbols then tap a symbol and select “Action Menu”. The list of actions include two different ways to save a Gmap4 link that includes your data.


More information on this map-in-a-link feature can be found in the following three places.


1. What’s new page

Note the tip about deleting the ll and z parameters from your Gmap4 link.



2. Example page

Scroll down to the section titled “Your map data saved in the Gmap4 link”. The examples range from basic to advanced and give you a quick way to see some of the kinds of maps you can make with this feature.



3. Help file

You can download the PDF file and search it (control-f) for the section titled “Make a custom map with Gmap4 and save it”.



Joseph, the Gmap4 guy

Redmond, WA

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