The "Egg Box" tutorial

How to use the "Progressive sum of surfaces" of Geomorph to build an "Egg Box" height field

An "Egg Box" height field is used in the Fourier Explorer tutorial. We'll see how to create it with the "progressive sum of surfaces" generation process. This creates a height field by adding up gaussian bells of different sizes, moved by a random amount on width, depth and height.

1. Calling the "Progressive sum of surfaces"

These are the default settings you get when choosing the "progressive sum of surface" icon in the "New document" dialog.

Notice that the first "shape filter" is global to the image, while the "shape filter" related to the "primitive surface" controls the gaussian bell used as a building block.

The "Seed" parameter is used to change pseudo-randomly the global distribution of the surfaces.

This is a scaled down version of the 512x512 height field generated.

2. Removing the random parameters

Without the random factor displacing the bells on the plane ("XZ Displacement"), or the one varying the height of the bells ("H Displacement"), we obtain a cracker-looking height field.
We increase the slope from 50 to 70 because the result has a too low altitude. This means using higher bells as building blocks.

We unroll the "Wave length control" for the next step...

3. Controlling the frequencies

Set all the wave lengths to 0, then set the 64-pixel to 100, and  you're done!

Written in April 2008

Contact:    Patrice St-Gelais Logo