Visibility and Hidden Surface Removal
Visibility and Hidden Surface Removal Visibility and Hidden Surface Removal
Scanline: scan example 3 • At scanline y = g: AET has AB, DE, BC, FE – Render background color and then ABC as before Computed incrementally as in z-buffer – At DE: invert in-out flag of DEF; check depth information of “in” polygons (ABC and DEF in a list of “in” polygons) – Render DEF – At BC: still render DEF if no penetration – At FE: go background – Next scanline © Machiraju/Zhang/Möller 60
Scanline: scan example 4 • Maintain a list of “in” polygons • Check depth information when entering into a new “in” polygon • If no penetration, there is no need to check depth when leaving obscured (occluded) polygons © Machiraju/Zhang/Möller 61
- Page 9 and 10: Visibility (6) • wireframe © Mac
- Page 11 and 12: Visibility (8) • Inter-object vis
- Page 13 and 14: Why compute visibility? • Realism
- Page 15 and 16: Classification of algorithms • Hi
- Page 17 and 18: Object Space for each object in wor
- Page 19 and 20: How to improve efficiency • Pay a
- Page 21 and 22: 1. Coherence • Why? — Object pr
- Page 23 and 24: 1. Edge and face coherence • Edge
- Page 25 and 26: 2. Use of projection normalization
- Page 27 and 28: 2. Perspective Transform • Can br
- Page 29 and 30: 3. Bounding Objects (2) • For ren
- Page 31 and 32: 3. Bounding Objects (4) • rectang
- Page 33 and 34: 4. Back-face culling • Assumption
- Page 35 and 36: 5. Spatial Partitioning • break a
- Page 37 and 38: 6. Hierarchy • Use (e.g., semanti
- Page 39 and 40: z-buffer algorithm revisited • On
- Page 41 and 42: z-buffer: exploiting depth coherenc
- Page 43 and 44: z-buffer: bilinear interpolation
- Page 45 and 46: List Priority (2) • Depth compari
- Page 47 and 48: List Priority (4) • Do extents in
- Page 49 and 50: List Priority (6) • Do polygons c
- Page 51 and 52: List Priority (8) • If these test
- Page 53 and 54: List Priority (10) • More example
- Page 55 and 56: Scanline: data structure • Recall
- Page 57 and 58: Scanline Example • Another repres
- Page 59: Scanline: scan example 2 • At sca
- Page 63 and 64: Scanline problems • Beware of lar
- Page 65 and 66: Building the BSP trees • Object s
- Page 67 and 68: BSP traversal example • Rendering
- Page 69 and 70: Warnock’s subdivision • Divide
- Page 71 and 72: Warnocks Algorithm (3) - Single sur
- Page 73 and 74: Warnock’s Algorithm • If none o
- Page 75: Final issues on area subdivision
Scanline: scan example 4<br />
• Maintain a list of “in” polygons<br />
• Check depth information when entering into<br />
a new “in” polygon<br />
• If no penetration,<br />
there is no need to<br />
check depth when<br />
leaving obscured<br />
(occluded) polygons<br />
© Machiraju/Zhang/Möller<br />
61
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