Lecture_Chapter3_c

Representations marching quads lookup table for

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Unformatted text preview: Chapter 3: Object Representation 80 Triangulating Implicit Representations •  Better: Marching Quads •  Examine corner values of individual cells (quads) •  Compare corner values to function value (isovalue) ECS 175 Chapter 3: Object Representation 81 Triangulating Implicit Representations •  16 cases for 2D Marching Quads ECS 175 Chapter 3: Object Representation 82 Triangulating Implicit Representations •  Marching Quads •  Lookup table for triangulation cases •  Creates geometry per cell/quad •  Piecewise linear representation •  Linear interpolation along edges pedge = (1 − t) · p0 + t · p1 ECS 175 Chapter 3: Object Representation fiso − f0 t= f1 − f0 83 Triangulating Implicit Representations •  Marching Quads – Summary •  Approximation quality dependent on sampling •  Non-uniform triangle sizes/line lengths •  Only linear representation per cell (connectivity information?) •  Highly parallelizable •  Seeding strategies possible ECS 175 Chapter 3: Object Representation 84 Raytracing Implicit Representations •  Alternative: Raytracing Image plane Ray through pixel center ECS 175 Chapter 3: Object Representation 85 Rendering Implicit Representations •  Raytracing: Follow ray after first intersection Shen – Wikimedia Commons ECS 175 Chapter 3: Object Representation 86 Creation of Object Representations •  Modeling and Animation Tools (CAD, CSG, …) •  Blender, Maya, 3D Studio Max, etc. Blender •  Procedural generation •  Reconstruction from measurements ECS 175 Chapter 3: Object Representation 87 Summary of Chapter 3 •  Different object representations may be used •  For efficient rendering and rasterization functions are tesselated into triangles •  Vertices, lines, triangles allow for quick rasterization and interpolation •  Attributes of vertices define colors, textures, etc. •  Up next: What can we “do” to these objects? ECS 175 Chapter 3: Object Representation 88...
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