Today's Topics: meshMesh- Mesh tessellation-Mesh simplification-Subdivision- Mesh parameterization: Seam computation
Today’s Topics: mesh Today’s Topics: mesh • Mesh – Mesh tessellation – M h i lifi i Mes h s implificat ion – Subdivision – Mes pa a ete at o : Sea co putat o h pa r a meterizat i o n: Seam co mputat i o n
·MeshDescription- A list of faces F = (fi,f,...,fn)· Each face is a triangle- A list of vertices V = (Vi,V2,...,Vn)Each face in F is a list of indices in Ve.g.fi --(V1,V2, V3 ), f2 --(V4, V5, V6)f3 --(V7,Vs, V9),
• Mesh Description – A li f f F (f A list o f faces F = (f1,f2,., fn ) • Each face is a triangle – A list of vertices V = (v1,v 2,.,v n ) – Each face in F is a list of indices in V e.g. f1-(v1,v 2,v 3 ), f2-(v 4,v 5,v 6 ), f3 -(v 7,v 8,v9 ),
Why mesh representation?: Computer generated 3D models and captureddata have different representations.- We need a unified representation in graphics- visual accuracy and speed should be acceptable- Due to fast development of graphics hardware,we could rasterize(光栅化)and render trianglesvery quickly nowadays
Why mesh representation? Why mesh representation? • Computer generated 3D models and captured data ha e different representations data ha v e different representations, – We need a unified representation in graphics – visual accuracy and speed should be acceptable – Due to fast development of graphics hardware Due to fast development of graphics hardware, we could rasterize(光栅化) and render triangles very qui kl d c y nowa days
Sourceof3Ddata: Models could be generated by:- Directly typing in the geometric file- Writing code to create such data: procedure modeling- Using modeling software such as 3ds/max, maya- Capturing a real model using a 3D scanner(3D扫描仪)- Reconstruction(重构) from one or more photographs(照片），calledphotogrammetry(照相测量法）- Combination of techniques above-Others
Source of 3D data Source of 3D data • Models could be generated by: – Directly typing in the geometric file Directly typing in the geometric file – Writing code to create such data: procedure modeling – U i d li ft h 3d / U s ing mo d eling software suc h as 3d s /max, maya – Capturing a real model using a 3D scanner(3D扫描仪 ) – Reconstruction(重构) from one or more photographs (照片), called photogrammetry (照相测量法 ) – Combination of techniques above – Others
Two main type of modelers: Solid-based usually seen in the area of Computer-Aided-Design(CAD), often emphasize modeling tools correspond toactual machining processes, such as cutting, drilling(钻孔),etc..Surface-based- do not have a built-in concept of solidity;-instead,allobjectsarethoughtofintermsofsurfacesDirect manipulation of surfaces, such as adding/deletingpolygons or vertices.-Easy for displaying
Two main type of modelers Two main type of modelers • Solid-based – usually seen in the area of usually seen in the area of Computer Computer -Aided-Design (CAD), often emphasize modeling tools correspond to actual machining processes, such as cutting, drilling( actual machining processes, such as cutting, drilling( 钻 孔), etc. • Surface -based – do not have a built-in concept of solidity; – instead all objects are tho ght of in terms of s rfaces instead, all objects are tho ught of in terms of s urfaces. Direct manipulation of surfaces, such as adding/deleting polygons or vertices polygons or vertices. – Easy for displaying