Questions about image-based height-field representations, commonly used to represent a terrain.
A height-field is a way of defining a surface with an image, where the co-ordinates of the image represent co-ordinates on a plane, and the intensity of the image at each point represents the height of the surface from the plane at that point.
It's a compact representation of 2.5D surfaces such as mountainous terrain, and is easier to create and modify in use than a polygon-based representation, but can't represent holes in the height field (such as a cave system or bridge).
Compare displacement map, which is essentially a height field on a smaller scale to represent microgeometry on a polygon mesh.
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