{"responseHeader":{"status":0,"QTime":6,"params":{"q":"{!q.op=AND}id:\"101802\"","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":"/e5/8f/e58fafa2c57189bdadbce2512d183a20f4737273.jpg","oldid_t":"compsci 9915","setname_s":"ir_computersa","restricted_i":0,"format_t":"application/pdf","modified_tdt":"2016-05-25T00:00:00Z","file_s":"/d7/e2/d7e2e1f4d73af7392b011bc15ce0f5af83434f5b.pdf","title_t":"Page 18","ocr_t":"6 2.2 Specular Highlights Under simplifying assumptions, light striking an object is reflected in one of two ways [11]. Diffuse reflection attenuates incident light and scatters it over a broad range of directions. Specular reflection produces highlights, where light reflects off the surface so the angle of incidence is roughly equal to the angle of reflection. The attenuations of incident light due to diffuse and specular reflection as a function of wavelength are not equal. Warnock recognized that .specular highlights are often close to the color of a light source, and he formulated a shading model where highlights were not affected by the color of a surface [37]. He proposed several shading rules, one of the most interesting being: where c is a constant selected so intensities result in a given display range, k. is the coefficient of specular reflection for the material, u is a constant greater than zero and less than two, and w is a constant between 20 and 60. As the values of u and w increase, the spread of light from diffuse and specular reflection, respectively, become narrower. The parameters in the shading model, including c and w, were subjectively adjusted to achieve pleasing results. 2.3 The Phong Model Phong extended this idea in two ways [28). (Note that this is distinct from the normal interpolation scheme he developed.) His formulation went beyond Warnock's to include light sources that were not at the point of view, and he enhanced k. by making it a function of the angle of incidence. He also removed the attenuation of the light to the surface based on IIlii. The formula for this model is","id":101802,"created_tdt":"2016-05-25T00:00:00Z","parent_i":101866,"_version_":1679953745189797890}]},"highlighting":{"101802":{"ocr_t":[]}}}