Software
Neutral Landscapes
I developed two programs to generate neutral landscapes using algorithms developed by Dietmar Saupe in The Science of Fractal Images (1988). Both programs give the user the option to generate multiple landscapes with the same general structure (i.e., generated using the same sequence of random numbers) but with different fractal dimensions. The landscapes are outputted as ascii files with ESRI headers that can be imported into ARC/VIEW or ARC/INFO. The landscapes contain integer values that are roughly centered at zero whose range depends on the selected fractal dimension.
- Fourier Filtering Method ZIP
- Midpoint Displacement Method ZIP
Planar Convex and Alpha Hulls
I developed a program that will take a set of points in two dimensions, inputted as x y coordinates in a space-delimited text file, and use the Graham's scan algorithm to generate the convex hull that contains those points (O'Rourke 1998, Computational Geometry, p. 77). The program outputs a file containing the points defining the vertices of the hull in ESRI polygon format. The area within the hull is outputed to the screen. I also developed a program that will take a set of points in two dimensions and use the Delauney triangulation algorithm to generate the alpha hull that contains those points (O'Rourke 1998, Computational Geometry, p. 187). The alpha hull provides a more detailed representation of the space contained by the points and allows for the removal of outlying points or poorly represented regions (Burgman & Fox 2003). Triangles can be excluded from the alpha hull by entering a triangle side length; the larger the value, the closer the alpha hull will be to the convex hull. The program outputs the points defining the vertices of the triangles in ESRI polygon format. The total area within the triangles is outputed to the screen.
- Convex Hull ZIP
- Alpha Hull ZIP