Terrain SimplificationThe image above generates an interesting optical illusion. The terrain in the middle is tilted (as per the offical Carnegie Mellon logo). The surrounding black rectangle is an axis-aligned rectangle. But, it looks slanted too. Nifty!
I spent a year or two working on issues relating to terrain simplification. The result was a paper and the Terra/Scape programs. However, I've moved on to other topics. I'm currently focused on simplifying arbitrary polygonal models. To find out about my current research, you can visit my page on multiresolution modeling .
I have not done any real development on my terrain software since January 1996, and I am unlikely to have any time to work on it any time soon. However, I have made a few small improvements now and then.
NEW: A whole new system for simplifying arbitrary polygonal models. See "QSlim" below.
NEW: A slightly improved version of scape is available (see below for details).
IE4 Users: A few people have reported problems downloading files with multiple periods in the file names using Internet Explorer 4. The download section below has links to IE-friendly zip files.
The algorithms used in the Scape software package are described in the
Fast Polygonal Approximation of Terrains and Height Fields,
by Michael Garland and Paul Heckbert.
Postscript files: pages 1-36 (black & white),
page 37 (color).
Also available as a single PDF file.
A related paper, Survey of Polygonal Surface Simplification Algorithms, by Paul Heckbert and Michael Garland, is also in the works. At one point, this was a companion paper for the one above which focused on various algorithms for terrain simplification. However, it has since evolved into a more general survey of surface simplification algorithms. It will be available by Summer 1997.
As I've mentioned above, it's been quite some time since I was actively developing my terrain simplification software. Instead, I have been working on the problem of simplifying arbitrary 3D polygonal models.
In October 1997, I released the first version of my QSlim software. It is based on the technique of surface simplification using quadric error metrics. It is not as fast and not as space-efficient as Terra/Scape, but it can simplify a much broader range of models. I am still actively developing both the simplification algorithms and the software implementation of QSlim.
The most recent version of Scape is version 1.2. It was released August 29, 1997. Scape is distributed in two pieces:
The following changes were made in Scape 1.2:
The following changes were made in Scape 1.1 (released January 17, 1996):
In December 1995, I started working on an improved version of Scape, called Terra. This software is easier to use and easier to understand. The code is cleaner, and it actually supports some useful features that Scape does not.
Terra was never actually finished, and I haven't had time to work on it for the past year. However, it should prove quite usable. You can find more details in the current documentation for Terra. If it sounds interesting, you're free to download the last snapshot of Terra 0.7 with the understanding that it is unfinished and may never be finished. You're free to use it, but you use it at your own risk.
Michael Garland firstname.lastname@example.org Last modified: Fri May 29 11:13:43 EDT 1998