This reposity is just an archive of the C source code from David Simpson's Dereth Cartography site which is no longer hosted at http://www.ugcs.caltech.edu/~dsimpson/. On Tuesday, November 26th, 2019, I copied the five C source files form the most recent Internet Archive snapshot (https://web.archive.org/web/20120505235544/http://www.ugcs.caltech.edu/~dsimpson/) and made this repo for posterity. All rights and credit go to David Simpson.

He notes:

The following source code is provided "as is," so don't expect much help. It should be easy to understand though.

Also, the source code provided below is meant to be executed from a command prompt, such as a DOS box or an xterm. They should compile using any standard C or C++ compiler on most platforms. They were all originally written in MS Visual C++, but I know that they compile just fine using gcc under Linux.