Flexible point-based rendering on mobile devices

We have seen the growing deployment of ubiquitous computing devices and the proliferation of complex virtual environments. As demand for detailed and high-quality geometric models increases, typical scene size (often including scanned 3D objects) easily reaches millions of geometric primitives. Traditionally, vertices and polygons (faces) represent 3D objects. These representations, coupled with the traditional rendering pipeline, don't adequately support display of complex scenes on different types of platforms with heterogeneous rendering capabilities. To accommodate these constraints, we use a packed hierarchical point-based representation for rendering. Point-based rendering offers a simple-to-use level-of-detail mechanism in which we can adapt the number of points rendered to the underlying object's screen size. Our work strives for flexible rendering - that is, rendering only the interior hierarchy nodes as representatives of the subtree. In particular, we avoid traversal of the entire hierarchy and reconstruction of model attributes (such as normals and color information) for interior nodes because both operations can be prohibitively expensive. Flexible rendering also lets us traverse the hierarchy in a specific order, resulting in a fast, one-pass shadow-mapping algorithm.