VH Data Sources

Where to get your own map files:

You can download your own map files off the internet (in a variety of formats).  Unfortunately, the USGS no longer appears to provide map data for free download (they did during the 90's).  As a result, the sources for free map data on the internet are spotty and you sometimes have to visit a number of them to get everything you need and in some cases, you just can't find what you are looking for.  The following web sites have been the most productive for me:

GIS Data Depot

http://www.gisdatadepot.com/catalog/US/index.html
This is where I tend to go first for my USGS data needs since their collection is the most complete (but is not 100% complete). This site has both free data and data you have to pay for.  They have free DEMs, and DLGs (both in SDTS format), but you usually have to pay for the DRGs and other larger files such as ortho-photos (map aligned aerial photos).  Luckily, the cost is trivial (a few cents per download).  You do have to register with them before you can download anything, but they have never sent me any spam, and they have a good reputation, so I feel pretty safe working with them.  They have DEMs, DLGs, and DRGs for most of the United States.  They also have ortho-photos for a few places in the country.  However, their web interface is unpleasant.  You have to tunnel down through "statewide data" and "county wide data" and then you have to know what county the quadrangle you want is in.  I rarely know this, so it's a real pain (quick, what county is the Chinook Pass, WA quadrangle in?).  Quadrangle index maps are available on the net for most states and they are very handy for figuring this type of information out.

Global Land Cover Facility

http://glcf.umiacs.umd.edu/index.shtml
I have recently discovered this site and it is VERY exciting.  It contains Landsat 7 photos, 15 to 30 meter resolution, map oriented/projected (orthorectified), for most of the world including all of the US.  Landsat gathers it’s images at a variety of wavelengths – none of which correspond particularly well with RGB.  However, a little tweaking with Adobe PhotoShop or GIMP makes some really nice texture maps with this imaging data.

Washington State Geospatial Data Archive

http://wagda.lib.washington.edu/
This excellent web site contains DEM, DLG and DRG data for all of Washington State (which has some very interesting topography--not to mention excellent hiking!).  It is also well organized and easy to navigate.

SDTS2DEM

http://www.cs.arizona.edu/topovista/sdts2dem/
This is a web site for a program that will convert SDTS format DEMs into the old ASCII DEMo format (which Virtual Hiker should be able to read).  This can serve as a work-around for users of VH Editor on platforms where my native SDTS reading library has not been compiled.  This program is historically important as well since it's late author (Sol Katz) answered many technical questions for me and helped me write my SDTS reader.  An early version of this sdts2dem was basically the father of my Java SDTS reading library.