Polygon surfaces:The most commonly used boundary representation for a three dimensional object is a set of polygon surfaces that encloses the object interior.
Polygon table: Representation of vertex coordinates,edges and other property of polygon into a table
form is called polygon table.
Polygon table can be organised into two groups: geometric table and attribute table.
Geometric table consists of vertex coordinates and other parameters which specify geometry of polygon.
Attribute table stores other information like colour , transparency etc.
Geometric table is further divided into vertex table, edge table and polygon table.
Vertex table: It stores each vertex present in a polygon.Each vertex stores x,y,z,coordinate information in the format v1:x1, y1, z1.
Edge table:The Edge table is used to store the edge information of polygon. Each edge stores the two vertex pointers in the table. It is represented in the table as E1: v1, v2.
Polygon table: Polygon table stores the surface of a polygon. It is represented in the table as S1: E1,E2,E3 where E1, E2, E3 are the edge pointers of the surface S1,
These three table representation stores each vertex one time and similarly each edge is also stored once thus avoiding common edge and vertex.
Since tables have many entries for large number of polygons, we need to check for consistency as it may be possible that errors may occur during input. To avoid that we add extra information into tables.
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