Triangle meshes are the most common representation of an object in the field of computer graphics. Recently, they have found their way into the field of erosion simulation, where volumetric representation used to prevail. Real-life erosion scenes are usually formed of multiple materials and so a reliable means of material definition is needed. Unfortunately, coupling the material information with a triangle mesh is not as straightforward as in the volumetric case. This paper proposes an approach for multiple material definition based on space subdivision. Binary space partitioning (BSP) is used to simulate complex multi material scenes. The approach allows the definition of a nontrivial scene composed of several materials, including the definition of a gradually changing material. A method for an automated creation of the BSP tree from input volumetric data is proposed. The construction algorithm extracts a triangle mesh as an intermediate product and uses its faces as the splitting planes of the BSP tree. (C) 2016 Elsevier Ltd. All rights reserved.