This directory stores shape files. Out of the many shape files that can be stored in SHAPEFILES, SPC only uses one shape model at a time, SHAPE.TXT. It is the main shape model used throughout SPC.
The first line of SHAPE.TXT is the Q size (between 8 and 512 in a factor of 2 increments: 8, 16, 32, 64, 128, 256, 512). The shape is in the ICQ format, which is basically a 6-sided cube. The number of vertices in the shape file is 6 * (Q+1)^2, so the number of lines in the shape file will be one higher.
Each subsequent line gives the vector of the surface. The vectors are in Cartesian space (x, y, z).
SHAPE00.TXT is the "baseline" shape model. This can be used to keep track of how different it becomes from the starting shape. Usually, it is turned off partway through the mission by INIT_LITHOS.TXT.
Use a symbolic link to specify SHAPE.TXT. This way, you can keep a useful filename in the directory, but "link" it to SHAPE.TXT so that SPC runs properly.
Here is a sample set of commands to show how to set up a link:
cd SHAPEFILES ln -s <realfile> SHAPE.TXT
Here is a sample of a shape model:
512 -278.04003 278.04003 268.57872 -276.88948 278.59369 269.11354 -275.73912 279.14388 269.64501 -274.58894 279.69061 270.17314 -273.43898 280.23391 270.69794 -272.28923 280.77377 271.21943 -271.13971 281.31022 271.73763 -269.99043 281.84328 272.25255 -268.84141 282.37296 272.76420 -267.69265 282.89927 273.27260 ...
(Compiled by KD)