Abstract: We present an efficient algorithm for building an adaptive bounding volume hierarchy (BVH) in linear time on commodity graphics hardware using CUDA. BVHs are widely used as an acceleration data structure to quickly ray trace animated polygonal scenes. We accelerate the construction process with auxiliary grids that help us build high quality BVHs with SAH in O(k*n). We partition scene triangles and build a temporary grid structure only once. We also handle non-uniformly tessellated and long/thin triangles that we split into several triangle references with tight bounding box approximations. We make no assumptions on the type of geometry or animation motion. However, our algorithm takes advantage of coherent geometry layout and coherent frame-by-frame motion. We demonstrate the performance and quality of resulting BVHs that are built quickly with good spatial partitioning.