{"responseHeader":{"status":0,"QTime":5,"params":{"q":"{!q.op=AND}id:\"95858\"","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":[{"modified_tdt":"2015-11-02T00:00:00Z","thumb_s":"/17/53/17538185bc980fae5b8f6711b30497fa419f4cf9.jpg","oldid_t":"compsci 3676","setname_s":"ir_computersa","file_s":"/92/0c/920c63aa11c0700456730b0d8b6d9bbc298e6c4b.pdf","title_t":"Page 26","ocr_t":"1. b tw n very two n ighboring c lls. Finally a br adth fir t ar h i appli t th D to decide global visibility orders of cells. treamlin s ar us d for visualizing v tor fi ld data [1 , 27 32, 41]. treamlines may penetrate several cells so in ord r to on Lru t them, it is necessary to follow them cell by cell. Therefore connectivity information fa data set is also required in vector field visualization. Since adjacency graphs are important data structures for FEA visualization they must be constructed efficiently. An algorithm has been developed by us to create an adjacency graph from a set of tetrahedral cells [40]. This algorithm is based on bin-sorting [21]. Its time complexity is linear in the number of cells. 3.2 Data Representation In FEA data sets, a tetrahedron is defined by four nodes, thus it is represented by a quadruplet of node indices, for example E = (nt, n2, n3, n4), where n1, n2, n3, and n4 are vertex indices. If no restriction is put on the order of the vertex indices, any quadruplet composed by the four indices defines the same cell E. In order to define a cell uniquely, the four indices are sorted in ascending order, i.e., n1 < n2 < n3 < n4. A face of a tetrahedron is comprised of three vertices; thus it can be described by a triplet of vertex indices. In FEA data sets, faces of cells are seldom explicitly stored, since it is easy to construct them from the definitions of cells. In order to have a unique definition of a face, the components of the triplets are enumerated in ascending order. By following this restriction, the four faces of cell E can be uniquely described as: (nt, n2, n3), (n1, n 2, n4 ), ( n1, n3, n4) and ( n2, n3, n4). Such definition of a face does not permit easy identification of a cell to which the face belongs. Moreover it does not contain any information on the ordering of faces of that cell. Therefore a record of five components is used to define a face in our work. The first three components of the record are the indices of the vertices defining the face, the fourth component is the index of the cell to which the face belongs, and the last component is the index of the face in the cell. Hereafter the faces of cell E are described as: (n1, n2, n3, E, 1), (n1, n2, n4, E, 2) , (n1, n3, n4, E, 3), and (n2, n3, n4, E, 4). These records are called face records. In Figure 3.2, an example is depicted to demonstrate data structures for an FEA data set. The first two columns depict the data structures for vertices (including coordinates and the function value of each vertex) and cells. These are the input FEA data. The list of face records created by our algorithm is contained in the third column.","restricted_i":0,"id":95858,"created_tdt":"2015-11-02T00:00:00Z","format_t":"application/pdf","parent_i":95941,"_version_":1642982571742593025}]},"highlighting":{"95858":{"ocr_t":[]}}}