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FGP (Subject) / Test 1 (Lesson)
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- Was ist "Genus of a surface"? Wieviele Löcher/Handles sie hat. Donut=1, Häferl = 1, FIdgetspinner = 3
- Was ist die Euler Formel? Das Verhältnis zwischen Faces, Vertices und Edges. V-E+F=2(1-g) (g ist Genus of Surface)
- Nenne 3 Mesh-Datenstrukturen Face-based Winged-edge-based Halfedge-based
- What is a parametric surface representation? A surface in Euclidian space that is defined by two parameters. R² and r(with little arrow)
- What is an implicit surface? A surface defined by a formula. Like a line is defined by x-y=0, a surface can be defined by x+2y-3x+1=0
- What is a method to assess the quality of a surface? Reflection lines are used to show discontinuities in normals.
- What's surface-based deformation? When the surface is deformed.
- What's free-form deformation? When a bounding box surrounding the object is deformed instead of the surface.
- What are the manifold conditions? Each edge only falls to 1-2 faces and faces incident to a vertex form a closed or open fan.
- How do you compute vertex normals for a triangle mesh? Using the vector cross product of the vertex positions.
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- How do you compute the face normals of a triangle mesh? Calculate the edge vectors (A-B) and then calculate the cross product of them.
- Name three undesirable features of meshes! Holes (can be filled using Liepa's hole filling algorithm) Close gaps, small overlaps (should be removed) Intersections Overlapping sheets (should be merged)
- What size does the local neighborhood have on smoothing? Larger neighborhood means better smoothing Smaller means better details
- How do you calculate the Voronoi Region? You take the circumscribing circle and then connect the middle point to the middle points of all edges.
- How do you calculate the Barycentric Area? You connect the vertices to the middles of the edges and take the intersection and connect it to all the middles of the edges.
- Explain the cotangent formula! Dot produkt durch absolut vom cross produkt