VMap0 Coverages

Warning: This documentation is generated from the metadata attached to the VMap0 tables themselves, and, unfortunately, much of that is incorrect (especially the f_code values). Where I have had a chance to check, I have printed the original, incorrect value crossed out and the correct value beside it.

To check the values actually used in a VPF table for yourself, take the following steps:

1. Locate the feature table file, ending in pft for a point feature, lft for a line feature, or aft for a polygon feature. For example, if your CD is mounted on /cdrom, the feature table file for the North American hydro inwatera feature will be /cdrom/vmaplv0/noamer/hydro/inwatera.aft.

2. Use the vpf-dump utility built in the TerraGear src/Lib/vpf/ subdirectory to display the contents of the table.

3. Pipe the display through grep, sort and uniq to get some statistics about what values appear and how often, i.e. vpf-dump inwatera.aft | grep f_code | sort | uniq -c:

         1	  Name: f_code
         1	  Thematic index name: f_code1.ati
    151426	  f_code=BH000
      1260	  f_code=BH090
   

4. Guess what they're actually supposed to be. In the case of f_code values, you can look at http://www.digest.org/html/gp4a-toc.htm for some clues.

5. Build a small scenery area and see if you were right.

6. Let everyone else know what you found by posting to the group list.