View-Dependent Refinement of Progressive Meshes

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View-Dependent Refinementof Progressive Meshes

• Hugues Hoppe
• Microsoft Research
• SIGGRAPH 97

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Rendering complex meshes
860,000 faces!
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Traditional level-of-detail
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View-Independent LOD Difficulties
distant
backfacing
outsideview frustum
100,000 faces
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View-dependent LOD
29,400 faces
different LODs coexistover surface
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Applications Related work
heightfields
parametricsurfaces
arbitrarymeshes
Cignoni etal 95 De Floriani etal
96 Lindstrom etal 96
Rockwood etal 89 Abi Ezzi etal 93 Kumar etal
95
Xia-Varshney 96
S
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Contributions

• Progressive mesh ? vertex hierarchy ? selective
  refinement
• Dependencies ? consistent framework
• View-dependent refinement criteria

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Review of progressive meshes
150
152
500
13,546
M0
M1
M175
Mn
base mesh
original mesh
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The PM representation
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Idea Selective refinement
M0
vspl0
vspl1
vspli-1
vspln-1
SIGGRAPH 96 incremental update not possible
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Parent-child vertex relations
vs
vsplit
vu
vt
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Vertex hierarchy
vspl0
M0
vspl1
vspl2
vspl3
vspl4
vspl5
PM
v2
v1
v3
M0
Xia Varshney 96
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Selective refinement
vspl2
vspl0
M0
vspl1
vspl3
vspl4
vspl5
v2
v1
v3
M0
Restrictions?
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Legality conditions?
vsplit
vu
vl
vr
vr
vl
vs
vt
ecol

• vsplit legal if
• vs is active
• vl and vr are active
• ecol legal if
• ? problem consistent?

SIGGRAPH96
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New vspl/ecol parametrizations
vsplit
fn3
fn1
fn1
vu
fn3
vs
fn0
fn2
fn0
fn2
vt
ecol
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Runtime algorithm
v1
v2
v3
M0
v5
v10
v11
v4
v8
v9
v7
v12
v13
v6
v12
v14
v15

• Algorithm
• incremental (frame coherence)
• efficient (15 of frame time)
• amortizable

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View-dependent refinement criteria

• 3 criteria
• view frustum
• surface orientation
• screen-space geometric error

See paper for details.
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(1) View frustum
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(2) Surface orientation
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(3) Screen-space geometric error
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All three criteria together
69,473 faces ? 10,528 faces 1.9 frame/sec ? 6.7
frame/sec
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Fast rendering triangle strips

• Greedy algorithm
• IRIS GLavg. 10-15 faces/strip
• OpenGLavg. 4.2 faces/strip

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Application Parametric surfaces
32 Bezier patches
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Geomorphs
smooth visual transitions
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VIDEO
view frustum (2-window terrain) screen-space
error (2-window terrain) silhouette refinement
(sphere)all 3 criteria including orientation
(teapot) arbitrary mesh (gameguy)geomorph flythro
ugh of gcanyon
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Summary

• Selective refinement framework
• View-dependent refinement criteria
• Real-time algorithm (fast, amortizable)
• Arbitrary progressive meshes? geometrically
  optimized refinement!

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Future work

• Memory management for large models
• Runtime generation of geomorphs
• Refinement criteria for surface shading
• Animated models