Computer Graphics Part 6 (Rasterization)

  1. What is another name for rasterization?
    scan conversion
  2. Describe the scanline algorithm (3 steps)
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    • span extrema: only turn on pixels on interior to avoid intruding other polygons (round up values on left, round down on the right)
  3. Explain the process of the span extrema and why it is used?
    • computing intersections of every line is really expensive and requires floating point arithmetic, instead use span extrema to manually "test out" the span extrema line by line, with simply incrementation of x, every time y overfloaws - thereby avoid floating point arithmetic.
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  4. span extrema pseudo code
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  5. How are the edges managed in the spanline alogithm?
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  6. Explain how the global edge table works
    • Edges are bucket sorted according to their minimum Y
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  7. How does the active edge table work?
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  8. Name two polygon fill rules
    • 1. do not include horizontal edges in the tables
    • 2. Vertices - if local max or min, count twice; otherwise count once to assure consistency
  9. Why are triangles easy to rasterize?
    • always convex
    • always ona¬† plane
    • never selfintersects
    • easy to interpolate data
  10. Barycentric coordinates - derivation
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  11. How are barycentric coordinates used within the context of triangle rasterization?
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  12. copmuting the barycentric coordinates
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  13. How is trianlge rasterization done using barycentric coordinates and a bounding box?
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  14. barycentric coordinates exercise
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  15. What are mean value coordinates?
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  16. Polygon Decompsoition algorithm
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    • If a vertex is inside that triangle, form a new triangle with leftmost inside vertx and A and procceed as before.
Card Set
Computer Graphics Part 6 (Rasterization)
University of Edinburgh School of Informartics Copmuter Graphics (Level 10) Revision Cards created by Simon M.