lecture22 - Perceptually Guided Interactive Rendering David...

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Perceptually Guided Interactive Rendering David Luebke University of Virginia
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Always start with a demo…
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Motivation: Preaching To The Choir Interactive rendering of large-scale geometric datasets is important Scientific and medical visualization Architectural and industrial CAD Training (military and otherwise) Entertainment
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Motivation: Model Size Incredibly, models are getting bigger as fast as hardware is getting faster…
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Courtesy General Dynamics, Electric Boat Div. Big Models: Submarine Torpedo Room 700,000 polygons
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(Anonymous) Big Models: Coal-fired Power Plant 13 million polygons
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16.7 million polygons (sort of) Big Models: Plant Ecosystem Simulation Deussen et al: Realistic Modeling of Plant Ecosystems
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Big Models: Double Eagle Container Ship 82 million polygons Courtesy Newport News Shipbuilding
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Big Models: The Digital Michelangelo Project David: 56,230,343 polygons St. Matthew: 372,422,615 polygons Courtesy Digital Michelangelo Project
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Motivation: Level of Detail Clearly, much of this geometry is redundant for a given view The basic idea: simplify the model, reducing the level of detail used for: Distant portions Small portions Otherwise unimportant portions
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Traditional Level of Detail In A Nutshell… 249,924 polys 62,480 polys 7,809 polys 975 polys Courtesy Jon Cohen Create levels of detail (LODs) of objects:
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Distant objects use coarser LODs: Traditional Level of Detail In A Nutshell…
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The Big Question How should we evaluate and regulate the visual fidelity of our simplifications?
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Regulating LOD LOD is often controlled by distance… d 1 d 2 Courtesy Martin Reddy
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Regulating LOD …or by size
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Measuring Fidelity Fidelity of a simplification to the original model is often measured geometrically: METRO by Visual Computing Group, CNR-Pisa
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Measuring Visual Fidelity However… The most important measure of fidelity is usually not geometric but perceptual: does the simplification look like the original? Therefore: We are developing a principled framework for LOD in interactive rendering, based on perceptual measures of visual fidelity
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Perceptually Guided LOD Several interesting offshoots: Imperceptible simplification How to guarantee simplification is undetectable? Best-effort simplification How best to spend a limited time/polygon budget? Silhouette preservation Silhouettes are important. How important? Gaze-directed rendering When can we exploit reduced visual acuity?
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Lots of excellent research on perceptually guided rendering Ramasubramanian et al (SIGGRAPH 99) But all this work has focused on realistic rendering algorithms (e.g., path tracing) Different time frame! Seconds or minutes versus milliseconds
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lecture22 - Perceptually Guided Interactive Rendering David...

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