an enhanced splatting method graphics and visualization group department of computer science the...

An Enhanced Splatting MethodAn Enhanced Splatting Method

Graphics and Visualization Group

Department of Computer Science

The University of Auckland

Peter Kulka & Richard Lobb

ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb

OverviewOverview

• Direct volume rendering

• High resolution splatting

• Results

• Conclusions and future work


Direct volume renderingDirect volume rendering

• Research area within visualization

• Rendering of 3D volume data sets– Volume reconstruction– Calculating an illumination model

• Two classes of algorithms:– Ray casting– Projection methods (splatting)


Volume reconstructionVolume reconstruction

• Problem:– Finding values between sample points


Illumination modelsIllumination models

• Assigning optical properties to the volume

• Emission-absorption model:– Volumes consist of light emitting particles– Particles also attenuate light from behind them

• Such a system can be described by:

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Ray castingRay casting

• Image order method

• Simulation of light flow along viewing rays

• Sharp images


SplattingSplatting

• Object order method

• Projection of each volume element onto the view plane

• Fast


MotivationMotivation

• Want:– Rendering speed of splatting– Image quality of ray casting

• Approach:– Correct errors in splatting

• Leads to three separate modifications

• Result: sharper images– We call this method high resolution splatting


Modifications to standard splattingModifications to standard splatting

• Reordering reconstruction and illumination calculations

• Correcting view angle distortions


Modifications (cont.)Modifications (cont.)

• Slicing the reconstruction kernel


High resolution splattingHigh resolution splatting

• Summary:


ComparisonComparison

• Test data set: CT scan of a human pelvis– Size: 256 256 110 sample points


ResultsResults

• Various rendering methods (close-up):

ray casting splatting high resolution splatting


ConclusionConclusion

• Three modifications to splatting:– Explicit volume reconstruction and illumination– Correcting of view angle distortions– Reconstruction along the line of projection

• Rendering times comparable to splatting

• Image quality comparable to ray casting


Future workFuture work

• More use of texture mapping hardware

• Perspective views

• Hierarchical versions– Building octrees– Wavelet splatting

an enhanced splatting method graphics and visualization group department of computer science the...

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