xtopo

Calculate and graphically display a topographic map of an artificial landscape

Authored and Contributed by: Ronald Joe Record
Description: The idea here is to calculate and display a fractal landscape topographically. In order to accomplish this, a midpoint displacement algorithm is used. The colors in the image represent heights in the landscape. Landscapes of varying "roughness" or "smoothness" can be calculated by varying the parameter "beta" which controls the fractal dimension.
Acknowledgements: The algorithm was derived from lectures given by Dietmar Saupe at the University of California at Santa Cruz. Assistance with colormaps and spinning color wheels and X was gleaned from Hiram Clawson and Stacey Campbell.
Build: To build the xtopo binary, either use the Imakefile or the sample makefile, Makefile.std. If your system doesn't support prototypes, uncomment the PROTODEFINE line of the Imakefile. After modifying the Imakefile appropriately, either use "xmkmf" or "imake" to create a Makefile. Then just type "make" to compile xtopo. The manual page can be formatted by typing "nroff -man xtopo.man > xtopo.6X".
Install: To install xtopo, copy the xtopo binary to the desired location (the sample makefile puts it in /usr/local/bin) Copy the formatted man page to wherever you keep your local doc (i use /usr/man/cat.LOCAL for imaging software), then add that location to your MANPATH.
Safety: I have used it for several years without harm.
Work Planned: None
Documentation: manual page.
Verification: You can test xtopo by just invoking it with no arguments. It should display a 512x512 image. Some workstations may be slow to calculate and display a map as there are lots of calculations involved. On a DECstation 5000/200 with 32 Mb memory, "time ./xtopo -V -d" gave a test timing of : real 0m17.46s user 0m5.30s sys 0m1.10s On a Compaq 33 MHz 386 with no co-processor and 10 Mb memory, the same command gave results of : real 4m18.09s user 4m7.32s sys 0m2.20s Some "interesting" ways to run xtopo are as follows : % xtopo -F -S 0 -m 0 -r -n 10 -d (use the full screen, set sea level to 0, minimum upper color index to 0, randomly select beta for each map, calculate 10 maps in demo mode) % xtopo -R -H 0.9 (display on the root window a landscape with paramter beta equal to 0.9) % xtopo -o topomap.ppm (calculate and display with default parameters and save the resulting image as a PPM file called topomap.ppm. this can be viewed later using xv or any PPM viewing utility)
Ideas, comments, additions, deletions, suggestions, bug reports, code review: e-mail Ronald Record at rr@sco.com or ...uunet!sco!rr.