It wasn’t long ago that if you wanted USGS maps you had to order them on paper or microfiche and if you wanted to do a map comparison, transferring your maps to a few sheets of transparent Mylar was your best bet. Now in about 30 minutes and a few clicks of a mouse and you are in business. With that thought in mind I just had to take a look at iGage All Topo Maps: Texas.

My civil surveying experience has been limited to a few acres at a time so I won’t try to critique their scale or coordinate translation, but from what I can tell looking at a San Antonio map both their coordinate location and distance is accurate in both miles and feet. How’d they do that? They used The UTM (Universal Transverse Mercator) which breaks the earth down into zones along the meridian and above and below the equator. The GPS (Global Positioning System) that is used to create all of this UTM data consists of twenty one active satellites orbiting 10,600 miles above the earth constantly sending us coordinate data. Before GPS you couldn’t even get two surveyors to plot the same piece of ground and come up with the same exact answer. Even the older commercially available GPS Receivers out there were not truly accurate down to the foot.

One of the things this program allows you to do is take one of their USGS Topographical Maps in either 1:24,000 or 1:250,000 scale and free hand draw a line in any twisted fashion you choose, from point A to point B, and it will give you the distance in feet, yards, meters or miles. You can zoom in and out on the map you are in with the mouse wheel or the zoom tool bar or change map scale on the fly without even losing your way point markers or spikes. To find a map you can search from a list of places like lakes or landmarks, parks or a list of cities. The software also allows you to search by GPS coordinates or a previously annotated way point.

All Topo Maps allows you to move way points to or from a GPS receiver like the Magellan, Garmin, etc. With everything from cell phones and cars to watches starting to come available with a GPS receiver, marking out a route from place to place with this program looks very compelling. You can even lay out your own hundred acre wood with GPS coordinates and the way point tools, derive 4 points, close them in and get the acreage and then print out a map at the scale and magnification you desire. For any of you who play GPS games like Geocaching where people stash trinkets to find with a receiver this could come in very handy. Don’t get to excited though while most of the USGS maps seem to be relatively current a few of them are from as far back as the 1960’s like Corpus Christi from1968 so the landmarks may not be current and will require comparison to a newer map.

The program comes with a seaming tool to pull adjacent maps together so that if your project included the eastern and western map of San Antonio you could pull them together to create one big map. The Big Topo feature requires you to find a N.W. or S.W. Corner or a centerline Quadrangle on the map to seam two to four maps together. Then press Control –X to copy to a clip board and cut and paste the corner location and limit the resulting maps size to suit your needs and (bang zoom) you’ve got a huge Map.

In working with this program I found the operation to be seamless and the tools easy to understand. It keeps the map that you were last viewing when you shut down the program on tap without even having to save it which saves time if you need the same view or a map adjacent to it. If you are planning to print maps the program lets you scale them to fit your page but if you have large areas I can see a lot of seaming letter size paper together or an E size plotter in your future. The only mild annoyance to me was that in zooming in and out the map would loose your place so drop in a waypoint or a spike to snap back to when you find a point of interest on the currently viewed to save time. 

Check out these Websites for more information on this program and the technical info related to it 

•  iGage 
•  Bike World 
•  David Rumsey Map Collection 
•  USGS 

All Topo Maps: Texas, comes in an eleven volume CD set and will run on a Pentium 90 with Windows 95 on up to Windows XP with patches from their Website, 200 megabytes of free space, though the installed files take up less than 100 Mb of hard drive space.