ViewDependent Refinement of Progressive Meshes Hugues Hoppe Microsoft

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View-Dependent Refinement of Progressive Meshes Hugues Hoppe Microsoft Research SIGGRAPH 97

View-Dependent Refinement of Progressive Meshes Hugues Hoppe Microsoft Research SIGGRAPH 97

Rendering complex meshes 860, 000 faces! V F

Rendering complex meshes 860, 000 faces! V F

Traditional level-of-detail 2, 000 faces 10, 000 faces 50, 000 faces pop[SIGGRAPH 96] progressive

Traditional level-of-detail 2, 000 faces 10, 000 faces 50, 000 faces pop[SIGGRAPH 96] progressive pop mesh representation linear sequence view-independent LOD

View-Independent LOD: Difficulties distant backfacing 100, 000 faces outside view frustum S

View-Independent LOD: Difficulties distant backfacing 100, 000 faces outside view frustum S

View-dependent LOD 29, 400 faces different LOD’s coexist over surface

View-dependent LOD 29, 400 faces different LOD’s coexist over surface

Applications & Related work height fields [Cignoni etal 95] [De Floriani etal 96] [Lindstrom

Applications & Related work height fields [Cignoni etal 95] [De Floriani etal 96] [Lindstrom etal 96] … parametric surfaces arbitrary meshes [Rockwood etal 89] [Xia-Varshney 96] [Abi Ezzi etal 93] [Kumar etal 95] … S

Contributions l Progressive mesh vertex hierarchy selective refinement l Dependencies consistent framework l View-dependent

Contributions l Progressive mesh vertex hierarchy selective refinement l Dependencies consistent framework l View-dependent refinement criteria

Review of progressive meshes 150 152 M 0 500 M 1 base mesh 13,

Review of progressive meshes 150 152 M 0 500 M 1 base mesh 13, 546 … M 175 … vertex split vl vs vr Mn original mesh vu vl edge collapse vt vr

The PM representation 152 150 M 0 vspl 0 500 M 175 … …

The PM representation 152 150 M 0 vspl 0 500 M 175 … … vspli i … … 13, 546 vspln-1 n-1 vspl Mn progressive mesh (PM) representation M 0 Mi Mn

Idea: Selective refinement M 0 vspl 1 vspli-1 vspln-1 [SIGGRAPH 96]: incremental update not

Idea: Selective refinement M 0 vspl 1 vspli-1 vspln-1 [SIGGRAPH 96]: incremental update not possible

Parent-child vertex relations vs vsplit vt vu

Parent-child vertex relations vs vsplit vt vu

Vertex hierarchy PM: M 0 vspl 2 v 1 M 0 v 10 Mn

Vertex hierarchy PM: M 0 vspl 2 v 1 M 0 v 10 Mn v 12 vspl 1 vspl 3 vspl 4 v 2 v 11 v 4 v 13 [Xia & Varshney 96] v 3 v 5 v 6 v 14 vspl 5 v 8 v 7 v 15 v 9

Selective refinement M 0 vspl 2 v 1 M 0 v 12 vspl 1

Selective refinement M 0 vspl 2 v 1 M 0 v 12 vspl 1 vspl 3 vspl 4 v 2 v 11 v 4 v 13 selectively refined mesh Restrictions? v 3 v 5 v 6 v 14 vspl 5 v 8 v 7 v 15 v 9

Legality conditions? vsplit vl vs vu vt ecol n vsplit legal if: – vs

Legality conditions? vsplit vl vs vu vt ecol n vsplit legal if: – vs is active – vl and vr are active n vr vl vr [SIGGRAPH 96] ecol legal if: – ? problem: consistent? [Xia&Varshney 96]: legal if identical neighborhood

New vspl/ecol parametrizations vsplit fn 1 fn 0 vs fn 3 fn 2 ecol

New vspl/ecol parametrizations vsplit fn 1 fn 0 vs fn 3 fn 2 ecol n vsplit legal if: – vs is active – fn 0, fn 1, fn 2, fn 3 are active n ecol legal if: – vt, vu are active – fn 0, fn 1, fn 2, fn 3 are adjacent fn 1 vu fn 3 fn 0 vt fn 2

Runtime algorithm v 1 M 0 v 12 v 11 v 13 previous mesh

Runtime algorithm v 1 M 0 v 12 v 11 v 13 previous mesh l Algorithm: n n n v 4 v 3 v 5 v 6 v 14 v 8 v 7 v 15 v 9 dependency new mesh incremental (frame coherence) efficient (~15% of frame time) amortizable

View-dependent refinement criteria 3 criteria: n view frustum n surface orientation n screen-space geometric

View-dependent refinement criteria 3 criteria: n view frustum n surface orientation n screen-space geometric error See paper for details. S

(1) View frustum view is unchanged too high too far right

(1) View frustum view is unchanged too high too far right

(2) Surface orientation view is unchanged oriented away

(2) Surface orientation view is unchanged oriented away

(3) Screen-space geometric error tolerance=0. 5 pixels refinement near silhouette coarser in distance

(3) Screen-space geometric error tolerance=0. 5 pixels refinement near silhouette coarser in distance

All three criteria together 69, 473 faces 10, 528 faces 1. 9 frame/sec 6.

All three criteria together 69, 473 faces 10, 528 faces 1. 9 frame/sec 6. 7 frame/sec S

Fast rendering: triangle strips Greedy algorithm: n n IRIS GL: avg. 10 -15 faces/strip

Fast rendering: triangle strips Greedy algorithm: n n IRIS GL: avg. 10 -15 faces/strip Open. GL: avg. 4. 2 faces/strip

Application: Parametric surfaces M V F preprocess PM M 0 1, 800 32 Bezier

Application: Parametric surfaces M V F preprocess PM M 0 1, 800 32 Bezier patches 25, 440 10, 000 vspl M 0 v 1 load Mn v 3 v 4 v 7 v 8 v 2 v 5 v 6

Geomorphs smooth visual transitions

Geomorphs smooth visual transitions

VIDEO view frustum (2 -window terrain) screen-space error (2 -window terrain) silhouette refinement (sphere)

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 flythrough of gcanyon

Summary l Selective refinement framework l View-dependent refinement criteria l Real-time algorithm (fast, amortizable)

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

Future work l Memory management for large models l Runtime generation of geomorphs l

Future work l Memory management for large models l Runtime generation of geomorphs l Refinement criteria for surface shading l Animated models