bullet ray vision
DESCRIPTION
Bullet Ray Vision. Lee A. Butler US Army Research Laboratory Abe Stephens University of Utah SCI Institute. Genesis. Contract to MAGI in 1966* Observation: projectiles passing through matter have similarity to photons passing through lenses. - PowerPoint PPT PresentationTRANSCRIPT
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Bullet Ray Vision
Lee A. ButlerUS Army Research Laboratory
Abe StephensUniversity of Utah
SCI Institute
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Genesis• Contract to MAGI in 1966*
– Observation: projectiles passing through matter have similarity to photons passing through lenses.
• MAGI later developed Synthavision and did most of the rendering for TRON(1982).
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Background• Photon transport was adapted to ballistic
penetration. The threat replaced the photon. The target replaced the lens.
• Ballistic penetration is like participating media. As the penetration occurs, there is interaction with the target media. Both the threat and the target are affected by the interaction.
• Computation is performed on the entire ray/object intersection, not just at the surface.– CSG was a natural geometric representation.
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Original Design• Everything is expensive to compute, so
allow everything to be re-used– Ray-geometry intersection was computed
and saved for re-use. Typically, penetration equations and parameters were altered for each use.
– Assumes a single ray/threat relationship.
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THOR• V50: Velocity at which 50% of fragments will
penetrate:V50(ft/sec) = 10c (h(in) Af(in
2))
Wf
(grains) sec
• Residual Velocity:
Vr(ft/sec) = V(ft/sec) – 10c (h Af)
Wf sec V
(ft/sec)
• Residual Weight:
Wr(grains) = Wf – 10c (h Af)
Wf sec V
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Cultural Evolution• Programmer-user to Application-user.
• Data re-use to application re-run.
• Single ray/threat relationship to multiple rays/threat relationship.
• Ray tracing slow to fast
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One Step Forward
Ray Depth Top Right Front A35Full 9.22 10.52 6.27 12.36Adaptive 7.30 10.54 3.15 7.60
View Computation Time (seconds)
• Interleave ballistic penetration calculations with ray/geometry intersection using classic BRL-CAD ray-tracer on CSG geometry.
• Nice performance improvement, but still slow.
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Two Steps Forward• Bullet Vision:
Since we’re ray tracing,
render the results of the
computation too.
Free visualization!
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Three Steps Forward• Implement computation as a shader in Manta
packet-based ray tracer.
– Need to collect in/out pairs before “shading.”
• What was a batch application is now
interactive. 3.9 fps on Intel Core 2 2.66Ghz
with 4 cores.
• Surprise: BVH Traversal is the major
bottleneck in the system. “Shader” with 14
exponentiation operations is distinct second.
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Interactive Rendering
Watch Video
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Future Work• Current work is a brute-force
implementation of the penetration equations. 14 exponential operations.
• There is ample opportunity to optimize the computation of the equations.
• This is a equation fit to measured data. Alternative equation fits that are more computationally friendly are possible.
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Future Work• BVH acceleration structure may not be
optimal for applications where “transparent” geometry is the norm. Some further investigations on acceleration structures for such applications is needed.
• Current frustum acceleration techniques may not be optimal for transparency and deferred shading algorithms.
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Funding
US Army Research Laboratory
The Center for the Simulation of Accidental Fires and Explosions
(C-SAFE) B524196