Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.
-
Upload
bonnie-stewart -
Category
Documents
-
view
223 -
download
0
Transcript of Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.
![Page 1: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/1.jpg)
Polygon Modelling
![Page 2: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/2.jpg)
3D Representation
Wire frameNURBS surfaceSolidVoxelMesh
![Page 3: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/3.jpg)
Polygon mesh
Any polygon mesh can be convert to triangle mesh
Can be rendered directly by graphic hardware
Easy to computeOne format, all geometries
![Page 4: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/4.jpg)
Facets and vectors
![Page 5: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/5.jpg)
Facets and vectors
Normal vector a facet determine its ‘direction’
Normals point to the OUTSIDEMost rendering software has ‘render back-
face’ optionFor facets without normal vector, direction
determine by Right-hand rule
![Page 6: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/6.jpg)
Euler Equation
V – E + F = 2 V – Vertex E – Edge F – Face
Polygon body must satisfy this relationTry it on a cube
![Page 7: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/7.jpg)
Features
![Page 8: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/8.jpg)
Edges, holes, and genii
Boundary edge – edge bounded by a single triangle
Hole – closed polygon of boundary edges Genus – ‘donuts’ of an object Physical object has neither boundary edge or
hole Most mesh formats has no build in check for
errors Similar to bitmap VS vector
![Page 9: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/9.jpg)
Manifold
Polygon models with holes or naked edges
The model is not ‘water-tight’ or ‘leaky’Will not satisfy Euler EquationOK for architectural, animation, etc.Not acceptable for RP
![Page 10: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/10.jpg)
Curve approximation
![Page 11: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/11.jpg)
Curve approximation
Polygon models usually are only close APPROXIMATION of physical object
The flatter, the more accurateThe more facets, the better
![Page 12: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/12.jpg)
File Size Implication
File size directly proportional to number of facet
Not related to physical sizeRelated to curvy/flat surface ratioRelated to number of small featuresRelated to resolution setting
![Page 13: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/13.jpg)
Computation efficiency
Use native polygon model: eg. 3D StudioMaintain internal polygon model for
rendering: eg. RhinocerosMeshes are also used for scientific
calculationHardware accelerated real-time smoothing
makes high quality renderings with coarse models
![Page 14: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/14.jpg)
Tessellation
Also called Triangulation or PolygonizationConversion of NURBS surface or solid
model to polygon surface
![Page 15: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/15.jpg)
The Large Carriage, by Xavier Veilhan, Jean Nouvel & Renzo Piano, by Xavier Veilhan,
![Page 16: Polygon Modelling. 3D Representation Wire frame NURBS surface Solid Voxel Mesh.](https://reader036.fdocuments.us/reader036/viewer/2022062308/56649ea25503460f94ba6400/html5/thumbnails/16.jpg)
Applications
Rapid prototyping Digital sculpting Rendering and Game Design collaboration