Grid Generation and Geometry Description
Here are some examples for the possibilities to use IBG.
More information about the IBG package is available via anonymous
ftp.
Example: Rügen Island (Germany):
This grid was created in the following way:
- A picture of the region around
Rügen was obtained with the Xerox PARC Map Viewer and
the xv grab function.
- xpaint was used to manipulate this picture:
- At first, a picture which contains
only two colors was created.
- The two segments have been subdivided into six more convex
subsegments with slightly different colors.
- The resulting picture has been
saved in the PPM format.
- The program
ibgmainpix.c was used to create the grid (with ca. 40 000 points
in 24 sec. on a VAX 4000/90).
The geometry description also allows to describe complex 3D geometries
containing intersections without explicite specification of the
intersection lines. So, the grid
was created using the program
ibgmain3line.c
Segments with nontrivial topology also can be simply
created. The grid
was created using the program
ibgmainhole.c
Using elevation data obtained from the
1-degree USGS Digital Elevation Models we have created the
following elevation profile:
Great Falls East:
Grand Canyon East:

An YDL output possibility allows to use the SGI powerflip program for
visualization:
Great Falls East:
Grand Canyon East: