{"responseHeader":{"status":0,"QTime":3,"params":{"q":"{!q.op=AND}id:\"101816\"","hl":"true","hl.simple.post":"","hl.fragsize":"5000","fq":"!embargo_tdt:[NOW TO *]","hl.fl":"ocr_t","hl.method":"unified","wt":"json","hl.simple.pre":""}},"response":{"numFound":1,"start":0,"docs":[{"file_name_t":"Malley-A_Shading_Method.pdf","thumb_s":"/fd/7f/fd7f125e09ab2c7e15fe9ef434b6ea505db4b378.jpg","oldid_t":"compsci 9929","setname_s":"ir_computersa","restricted_i":0,"format_t":"application/pdf","modified_tdt":"2016-05-25T00:00:00Z","file_s":"/e0/b0/e0b00f6a4789d7b8ac63d16dd4a52547f0160b9c.pdf","title_t":"Page 32","ocr_t":"CHAPTER 3 THE RAY INTERSECTION PROBLEM: PREVIOUS WORK The expense of ray tracing is based on determining ray intersections. The ray intersection problem is the following: given a representation for geometric objects in an environment and a ray starting point and direction, what is the first (nearest) object intersected by the ray? This query must be answered many times in producing a ray traced image, and has been a bottleneck in ray tracing computation. 3.1 Naive Ray Tracing Ray tracing by testing all objects against a given ray - the naive approach - is computationally exorbitant. Each object is tested against a ray, and in the event that a ray intersects an object, the distance to the object is computed and compared to any previous intersections with the ray. After testing all objects, the closest object is the object of interest. Since the number of geometric primitives in a. ray traced image may number in the hundred thousands or more, and the number of rays to be intersected is likely to exceed several hundred thousand, this approach is impractical. 3.2 Hierarchical Bounding Volumes Rubin and Whitted proposed a method for clustering objects in a scene into hierarchical bounding volumes [30]. In that scheme, a programmer manually established clusters of objects in a scene, and a parallelepiped was calculated that","id":101816,"created_tdt":"2016-05-25T00:00:00Z","parent_i":101866,"_version_":1679953745193992192}]},"highlighting":{"101816":{"ocr_t":[]}}}