Shells, crabs and seahorses:
expanding the modeling power of implicit surfaces

Andrei Sherstyuk
Department of Computer Science
Monash University

Abstract:

There are few objects in the natural world that can be adequately represented by linear, circular or planar primitives. We show that in the domain of implicit modeling such primitives are very useful. Lines, arcs and triangles, when used as skeletons of convolution surfaces, produce well-structured and compact datasets that are easy to manipulate and animate.

We discuss a number of new modeling techniques and a number of datasets, that yield visually convincing shapes, resembling various forms of marine life. We also present volumetric textures that alter the actual geometry of implicit surfaces and make them more realistic.

Keywords: natural forms, geometric modeling, convolution surfaces, implicit surfaces.

Here are some images from the paper:

	The 3D skeleton and the convolved surface of an Unidentified Mollusk. The skeletal elements are pictured as cylinders to emphasize the spiral structure better.
	The hand drawing (bare skeleton), the 3D skeleton and the convolved shape of a sea-horse. Note how the wrinkles indicate the softness of the skin.
	Trapezia rufopunctata (or just a coral crab). The simplified 3D skeleton consists of 7 polygons (body), 26 arcs (limbs, claws and eye sockets) and 2 spheres (eyes). The convolved version has additional 608 cylindrical spikes, scattered along the surface. Possibly, the most interesting implicit model up to date. In the whole world :-)