195913064
Automatic Animation Skeleton Construction Using Repulsive Force Field
A method is proposed in this paper to automatically generate the animation skeleton of a model such that the model can be manipulated according to the skeleton. With our method, users can construct the skeleton in a short time, and bring a static model both dynamic and alive.The primary steps of our method are finding skeleton joints, connecting the joints to form an animation skeleton, and binding skin vertices to the skeleton. Initially, a repulsive force field is constructed inside a given model, and a set of points with local minimal force magnitude are found based on the force field. Then, a modified thinning algorithm is applied to generate an initial skeleton, which is further refined to become the final result. When the skeleton construction completes, skin vertices are anchored to the skeleton joints according to the distances between the vertices and joints. In order to build the repulsive force field, hundreds of rays are shot radially from positions inside the model, and it leads to that the force field computation takes most of the execution time. Therefore, an octree structure is used to accelerate this process. Currently, the skeleton generated from a typical 3D model with 1000 to 10000 polygons takes less than 2 minutes on a Intel Pentium 4 2.4 GHz PC.
720356
Using Intel Streaming SIMD Extensions for 3D Geometry Processing
Three dimensional (3D) graphics applications is an important workload running on today's computer system. A cost-effective graphics solution is to use a general processor for 3D geometry processing and a specialized hardware for rasterization. 3D geometry processing is an inherently parallel task. Therefore, many CPU vendors add SIMD (Single Instruction Multiple Data) instruction extensions to accelerate 3D geometry processing. In this paper, we evaluate the performance impact of using the Intel Streaming SIMD Extensions (SSE) for 3D geometry processing. We use SIMD-FP to improve the computational throughput by processing four vertices in parallel. We find that the layout of vertices in memory is important for the effectiveness of SIMD-FP. We also study the effect of using prefetch instructions to improve the memory performance. The experimental results show that using Intel SSE can achieve close to 4x speedup for geometry processing.
7588542
Instance-based Schema Matching for Web Databases by Domain-specific Query Probing
In a Web database that dynamically provides information in response to user queries, two distinct schemas, interface schema (the schema users can query) and result schema (the schema users can browse), are presented to users. Each partially reflects the actual schema of the Web database. Most previous work only studied the problem of schema matching across query interfaces of Web databases. In this paper, we propose a novel schema model that distinguishes the interface and the result schema of a Web database in a specific domain. In this model, we address two significant Web database schema-matching problems: intra-site and inter-site. The first problem is crucial in automatically extracting data from Web databases, while the second problem plays a significant role in meta-retrieving and integrating data from different Web databases. We also investigate a unified solution to the two problems based on query probing and instance-based schema matching techniques. Using the model, a cross validation technique is also proposed to improve the accuracy of the schema matching. Our experiments on real Web databases demonstrate that the two problems can be solved simultaneously with high precision and recall.