Extending the CSG tree. Warping, blending and Boolean operations in an implicit surface modeling system

Automatic blending has characterized the major advantage of implicit surfac e modeling systems. Recently, the introduction of deformations based on spa ce warping and Boolean operations between primitives has increased the usef ulness of such systems. We propose a further enhancement which will extend the range of models that can be easily and intuitively defined with a skele tal implicit surface system. We describe a hierarchical method which allows arbitrary compositions of models that make use of blending, warping and Bo olean operations. We call this structure the BlobTree. Blending and space w arping are treated in the same way as union, difference and intersection, i ,e. as nodes in the BlobTree. The traversal of the BlobTree is described al ong with two rendering algorithms,. a polygonizer and a ray tracer. We pres ent some examples of interesting models which can be made easily using our approach that would be very difficult to represent with conventional system s.