Weightmaps are a method of deriving topological features from heightmap data. Types of weightmaps include by-altitude, by-direction, by-slope, by-flow, and others such as convexity. Weightmaps essentially provide masks that can be used by artists to apply textures algorithmically to specific terrain topology features, such as grass on flat-lands (low slope weightmap) or snow on mountain peaks (high altitude weightmap). Extracting the mask data from the terrain topology is an art in itself, requiring various styles of mathematical examination of the terrain layout.
Over the past few weeks I have been working on developing the Mask and Weightmap dialogs and functions including their use in the world creation stack.
The following images show three weightmaps derived from a digital-elevation-model terrain.
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