Penumbra Maps: Approximate Soft Shadows in Real-Time Chris Wyman and Charles Hansen University of Utah Speaker: Alvin Date: 9/29/2003 EUROGRAPH 2003.

Penumbra Maps: Penumbra Maps: Approximate Soft Shadows in Approximate Soft Shadows in

Real-TimeReal-Time

Chris Wyman and Charles HansenChris Wyman and Charles HansenUniversity of UtahUniversity of Utah

Speaker: AlvinSpeaker: Alvin

Date: 9/29/2003Date: 9/29/2003

EUROGRAPH 2003EUROGRAPH 2003

Alivn/GAME LAB/CSIAlivn/GAME LAB/CSIE/NDHUE/NDHU

Penumbra Maps: Approximate SofPenumbra Maps: Approximate Soft Shadows in Real-Timet Shadows in Real-Time

22

OutlineOutline

IntroductionIntroduction Penumbra MapPenumbra Map DiscussionDiscussion ResultResult Conclusions and Future WorksConclusions and Future Works



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IntroductionIntroduction

Shadow Map + Penumbra MapShadow Map + Penumbra Map Three-pass processThree-pass process

Renders a standard shadow map.Renders a standard shadow map. Renders the penumbra map.Renders the penumbra map. Renders the final image.Renders the final image.

Penumbra Map = Light Intensity MapPenumbra Map = Light Intensity Map



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IntroductionIntroduction

Shadow Map (left) and Penumbra Map (right).



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Penumbra MapPenumbra Map

Input: (See from the light center)Input: (See from the light center) A standard shadow map.A standard shadow map. Silhouette vertices and edges.Silhouette vertices and edges.

Use Haines’ shadow plateaus.Use Haines’ shadow plateaus.



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Penumbra Cone & SheetPenumbra Cone & Sheet



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FragmentFragment

i

i

i VP

VF

VP

FP

ZZ

ZZ

ZZ

ZZI

1

32 23' III (Bernstein interpolant)



88

DiscussionDiscussion

Overlapping penumbra.Overlapping penumbra. As an area light increases in size, As an area light increases in size,

silhouettes vary more over the light silhouettes vary more over the light so the generated shadows will so the generated shadows will become less realistic.become less realistic.

As a shadow’s umbra size shrinks, As a shadow’s umbra size shrinks, there are noticeably larger, darker there are noticeably larger, darker shadows.shadows.



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Overlapping PenumbraOverlapping Penumbra



1010

ResultResult



1111

ResultResult



1212

ResultResult



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Conclusions and Future Conclusions and Future WorksWorks

Rendering approximate soft shadows Rendering approximate soft shadows in real-time.in real-time.

Allow dynamical models to cast soft Allow dynamical models to cast soft shadows.shadows.

Approximate a full penumbra using Approximate a full penumbra using vertex programs to adjust the vertex programs to adjust the silhouette edge points.silhouette edge points.

Implement in hardware.Implement in hardware.

Penumbra Maps: Approximate Soft Shadows in Real-Time Chris Wyman and Charles Hansen University of Utah Speaker: Alvin Date: 9/29/2003 EUROGRAPH 2003.

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