Visibility and Hidden Surface Removal
Visibility and Hidden Surface Removal Visibility and Hidden Surface Removal
1. Depth and frame coherence • Depth coherence – once the depth of one surface point is computed, the depth of the rest of the surface can be found from a difference equation (e.g., in z-buffer) – adjacent parts of a face have similar depth values • Frame coherence – images in a sequence (e.g., animation) will likely change little from one to the other, so can reuse information from current frame – key to © Machiraju/Zhang/Möller compression 24
2. Use of projection normalization • Want to determine whether point P 1 obscures P2 • Need to see whether two points are on the same projector • With our projection normalization, just need to check the x and y’s of P’ 1 and P’ 2 © Machiraju/Zhang/Möller 25
- Page 1 and 2: Visibility and Hidden Surface Remov
- Page 3 and 4: Reading • Angel - Chapter 6.10-6.
- Page 5 and 6: Visibility (2) • Connecting dots
- Page 7 and 8: Visibility (4) • Include shading
- 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: 1. Edge and face coherence • Edge
- 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 and 60: Scanline: scan example 2 • At sca
- Page 61 and 62: Scanline: scan example 4 • Mainta
- 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
1. Depth <strong>and</strong> frame coherence<br />
• Depth coherence<br />
– once the depth of one surface point is<br />
computed, the depth of the rest of the surface<br />
can be found from a difference equation (e.g.,<br />
in z-buffer) – adjacent parts of a face have<br />
similar depth values<br />
• Frame coherence<br />
– images in a sequence (e.g., animation) will<br />
likely change little from one to the other, so can<br />
reuse information from current frame – key to<br />
© Machiraju/Zhang/Möller<br />
compression 24
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