HART: A Hybrid Architecture for Ray Tracing Animated Scenes (original) (raw)

2015, IEEE Transactions on Visualization and Computer Graphics

We present a hybrid architecture, inspired by asynchronous BVH construction [1], for ray tracing animated scenes. Our hybrid architecture utilizes heterogeneous hardware resources: dedicated ray-tracing hardware for BVH updates and ray traversal and a CPU for BVH reconstruction. We also present a traversal scheme using a primitive's axis-aligned bounding box (PrimAABB). This scheme reduces ray-primitive intersection tests by reusing existing BVH traversal units and the primAABB data for tree updates; it enables the use of shallow trees to reduce tree build times, tree sizes, and bus bandwidth requirements. Furthermore, we present a cache scheme that exploits consecutive memory access by reusing data in an L1 cache block. We perform cycle-accurate simulations to verify our architecture, and the simulation results indicate that the proposed architecture can achieve real-time Whitted ray tracing animated scenes at 1920×1200 resolution. This result comes from our highperformance hardware architecture and minimized resource requirements for tree updates. Index Terms-Ray tracing, bounding volume hierarchy, dynamic scene, graphics hardware ! 1 INTRODUCTION Recently, a great deal of research has been conducted to achieve ray tracing dynamic scenes at interactive rates [2]. In dynamic scenes, objects can be moved, added or deleted from a scene, or animated with topological changes. Because most ray-tracing systems are based on acceleration data structures, such as kdtrees, bounding volume hierarchies (BVHs), and grids, these acceleration data structures should be effectively updated for dynamic scenes. Many researchers have exploited CPUs [1], [3]-[11], GPUs [12]-[16], MIC (many integrated core) [11], [17], or dedicated raytracing hardware [18]-[20] to achieve this goal. However, most current real-time rendering engines (e.g. game engines) use techniques based on rasterization instead of ray tracing. This means that current ray-tracing systems still do not provide sufficient performance for the real-time rendering of dynamic scenes on commodity hardware. To achieve ray-tracing in dynamic scenes at real-time rates, there are two requirements: to get high-quality effects, the ray traversal performance must be high; and there must be fast acceleration-data-structure updates that do not degrade the tree quality. To achieve these two goals, we present a hybrid ray-tracing architecture based on the BVH. In this