{"responseHeader":{"status":0,"QTime":9,"params":{"q":"{!q.op=AND}id:\"98105\"","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":"Donahue-Modeling_Complex.pdf","thumb_s":"/c3/2d/c32d351cff0b505d4974e7d5622a64968c3ba1da.jpg","oldid_t":"compsci 6218","setname_s":"ir_computersa","restricted_i":0,"format_t":"application/pdf","modified_tdt":"2016-04-27T00:00:00Z","file_s":"/9b/aa/9baac38a1d8c9d7beb26084f1a6ccb1acf11b612.pdf","title_t":"Page 23","ocr_t":"13 Although this approach is quite useful in some cases, it can become quite difficult for more complicated shapes (consider constructing a tube along a highly curved path; this would require many bends or warps). 3.2 Existing Surface Design Operators Traditional techniques for surface design have been basically limited to: 1. Surface fitting by interpolation or approximation. 2. Interactive positioning of control points. 3. Surface modification by alteration or addition of control points. 4. Various lofting techniques. 5. Surface from curve(s) operations (such as Coon's patches, ruled surfaces, surfac·es of revolution and linear extrusions). The first four techniques require an initial approximation to the surface or data points from an existing model. Of the tools in the fifth category, linear ex-trusions and surfaces of revolution are perhaps the most intuitive and hence useful surface design operators. Although these technologies have existed for many years, they often prove inadequate because: 1. Traditionally, surfaces have been generated by rotating a curve about a straight line, leading to \"cylindrical\" surfaces, where, in fact, a curved axis might represent the object better. Although piecewise methods do exist, maintaining continuity conditions between the \"pieces\" is cumbersome. 2. Rotating a single curve around a line always results in a surface which is symmetrical about the line, and in fact, results in a surface whose cross section is a circle. This is not always desired. A much larger domain of objects can be modelled if these ideas are generalized. In [7], Carlson has described a series of interesting generalizations of the surface of revolution. By allowing the cross section (termed the trajectory by Carlson) to be any arbitrary closed planar curve, the domain of objects that a surface of revolution can represent is increased to include those objects which are topologically equivalent to a cylinder. Carlson also allows blending of cross sections; the cross section used at a particular axis point may be a linear","id":98105,"created_tdt":"2016-04-27T00:00:00Z","parent_i":98160,"_version_":1642982591214649346}]},"highlighting":{"98105":{"ocr_t":[]}}}