Blob Tree Trees

Abstract

In recent years several methods for modelling botanical trees have been proposed. The geometry and topology of tree skeletons can be well described by L-systems, however there are several approaches to modelling smooth surfaces to represent branches, and not all of the observed phenomena can be represented by current methods. Many tree types exhibit non-smooth features such as branch bark ridges and collars. In this paper we present a botanical tree modelling approach that uses a hierarchical implicit modelling system. The BlobTree provides several techniques to control the combination of primitives, and allows both smooth and non-smooth effects to be combined in a single blend volume in an easily controlled fashion. We use the BlobTree to produce models of botanical tree branching structures that capture smooth branching, branch collars and branch bark ridges in a single model. The BlobTree is used as a procedural surface modelling system, taking input from L-system botanical tree descriptions. We show that smooth, C1 continuous blends can be obtained without noticeable bulging, using summation blending. We implement irregular effects using Precise Contact Modelling, Constructive Solid Geometry and space warping.