…and other cool graphics stuff
David Luebke
University of Virginia
Overview
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I’ll talk about a bunch of current
projects:
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Scanning Monticello
Immersive display
Level of detail
GPGPU
Interactive ray tracing
Graphics architectures
Scanning Monticello
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Fairly new technology: scanning the
world
Scanning Monticello
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Want a flagship project to showcase this
Idea: scan Thomas Jefferson’s Monticello
– Historic preservation
– Virtual tours
– Archeological and architectural research,
documentation, and dissemination
– Great driving problem for scanning &
rendering research
Scanning Monticello—Demo
Scanning Monticello:
Where To Next?
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Building structured light scanner
– Idea:
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Shine bars of light at object
Discern its shape from their shape
– Jeff Peirson is building a portable structuredlight rig for scanning objects, friezework,
and so on at Monticello
Scanning Monticello:
Where To Next?
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Capture high dynamic range color to go
with scanned geometry
– Show HDR, tone mapping examples
– Idea:
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Scan w/ laser, then take lots of pictures
Lots of pictures, different exposures, different
locations (maybe even video?)
Figure out camera location very accurately
For all “correct” pixels in each image:
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Project onto geometry
Store for that location and direction
– Might work with Rhythm & Hues on this
Immersive Display:
New Orleans Museum of Art
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Jefferson’s America & Napoleon’s France
– Major exhibition commemorating
bicentennial of the Louisiana Purchase
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Included a “Virtual Monticello” exhibit
– Virtual window
– Barrier stereogram
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Show NOMA videos
Immersive Display:
Here at UVA
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We have the pieces of a cool virtualreality immersive display system
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Screens (3 silver, 2 rear-projection)
Projectors (6 dedicated, 3 others)
Head tracker
Spatial audio
Even part of the NOMA “window”!
Need to bring all the pieces together
– Got a good start already
Immersive Display:
Research
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Design and conduct experiments with
perception lab
– Study the perceptual/cognitive effects of
added layers of realism
– Almost guaranteed to produce papers
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Also fits into other research efforts
– Perceptual level of detail/animation
– Perceptual interactive ray tracing
– Chromium
Level of Detail
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A recurring theme in computer graphics:
trade fidelity for performance
– Reduce level of detail of distant, small, or
unimportant objects
249,924 polys
62,480 polys
7,809 polys
975 polys
Level of Detail
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A recurring theme in computer graphics:
trade fidelity for performance
– Reduce level of detail of distant, small, or
unimportant objects
Level of Detail:
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Big models!
– David: 56 million polygons
– St. Matthew: 372 million polygons
Courtesy Digital Michelangelo Project
Motivation
Level of Detail Research:
VDSlib
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Comparatively recent technique:
continuous level of detail
– Adapt LOD continuously, not discrete chunks
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Better fidelity/triangle
Hard to make fast on today’s hardware
– VDSlib: efficient view-dependent LOD
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Cool data structures & algorithms
Could make a big difference in 3D game design
Still work to be done to make fast enough
Level of Detail Research:
GLOD
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GLOD:
– High-level library for LOD in OpenGL
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Goal: make high-quality LOD easy to integrate in
games and other graphics applications
Includes and interfaces with VDSlib
Cool software (interface design) issues
Free membership in the Church of Glöd
– Show GLOD video
GPGPU
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General-purpose computation on graphics
hardware (GPUs)
Modern GPUs are fantastically capable
– Extremely programmable
– Full floating-point precision
– Fast, so fast (20 GFLOPS sustained on GFX 5900)
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We want to harness that power for scientific
computing
– But it’s harder than it sounds
GPGPU:
CA Simulations on GPU
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Promising domain: cellular automata (CA)
simulations
– Ex: Conway’s “Game of life”
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Application: modeling cardiac tissue fibrillation
– Collab with Don Jordan, MAE, and med school
personnel
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Possible application: simulate microvascular
remodeling
– Collab with Tom Skalak, BME
GPGPU:
Other domains
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Fluid mechanics simulation
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Flow across a flapping wing
Modeling viscoelastic fluids
Joint work with Hossein Haj-Hariri, MAE
Cool math (PDEs)
Heat transfer
– Simulating heat propagating across chip
– Joint work with Kevin Skadron, Mircea Stan
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Others…
The Big Question
How should we evaluate and regulate the
visual fidelity of our simplifications?
Measuring Fidelity
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Fidelity of a simplification to the original
model is often measured geometrically:
METRO by Visual Computing Group, CNR-Pisa
Measuring Visual Fidelity
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However…
– The most important measure of fidelity is usually
not geometric but perceptual: does the
simplification look like the original?
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Therefore:
– We are developing a principled framework for LOD,
based on perceptual measures of visual fidelity
Perceptual LOD
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Idea: measure local simplification
measures against a perceptual model to
predict whether the user can could see
the effect of simplification
Model: contrast sensitivity function
Perception 101:
Contrast Sensitivity Function
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Contrast grating tests produce a contrast
sensitivity function
– Threshold contrast
vs. spatial frequency
– CSF predicts the
minimum detectable
static stimuli
Your Personal CSF
Campbell-Robson Chart by Izumi Ohzawa
Perceptual Graphics:
Where To Next?
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Incorporate eccentricity, velocity (attention?)
Protect copyrighted media: imperceptible
“watermarking” via mesh distortion
Interactive ray tracing…
Interactive Ray Tracing
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Interactive ray tracing
– Once a joke, now a reality
– Interesting opportunity: prioritized pixel
sampling for perceptually driven rendering
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Sample edges, center of gaze, etc more
Requires reconstruction of sparse samples!
Cool perceptual, signal processing issues
System: OpenRT
– Would like to install on our 24-node cluster
– Cool systems hacking issues
Graphics Architecture
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We are exploring research topics in
computer graphics architecture
– Thermal-aware graphics
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Joint work with Kevin Skadron
– Building a simulator to explore these and
other issues
My Projects:
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Proposed projects:
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–
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–
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Scanning Monticello
Immersive display
Level of detail
GPGPU
Perceptual graphics
Interactive ray tracing
Graphics architecture
Summary
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Proposed projects:
– Scanning Monticello
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
–
–
–
–
–
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Structured light
HDR capture
Immersive display
Level of detail
GPGPU
Perceptual graphics
Interactive ray tracing
Graphics architecture
Summary
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Proposed projects:
– Scanning Monticello
– Immersive display
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System building
Perception expts
Level of detail
GPGPU
Perceptual graphics
Interactive ray tracing
Graphics architecture
Summary
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Proposed projects:
– Scanning Monticello
– Immersive display
– Level of detail
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–
–
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VDSlib
GLOD
GPGPU
Perceptual graphics
Interactive ray tracing
Graphics architecture
Summary

Proposed projects:
–
–
–
–
Scanning Monticello
Immersive display
Level of detail
GPGPU


CA sims
Fluid/heat sims
– Perceptual graphics
– Interactive ray tracing
– Graphics architecture
Summary

Proposed projects:
–
–
–
–
–
Scanning Monticello
Immersive display
Level of detail
GPGPU
Perceptual graphics
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LOD/ray tracing
Watermarking
Integrate w/ display
– Interactive ray tracing
– Graphics architecture
Summary
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Proposed projects:
–
–
–
–
–
–
Scanning Monticello
Immersive display
Level of detail
GPGPU
Perceptual graphics
Interactive ray tracing
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Perceptual heuristics
Sampling/recon
– Graphics architecture
Summary

Proposed projects:
–
–
–
–
–
–
–
Scanning Monticello
Immersive display
Level of detail
GPGPU
Perceptual graphics
Interactive ray tracing
Graphics architecture
Summary

Proposed projects:
–
–
–
–
–
–
–
Scanning Monticello
Immersive display
Level of detail
GPGPU
Perceptual graphics
Interactive ray tracing
Graphics architecture

Desired student
attributes:
– Willing to commit 10-15
hours per week
– Self-starter
– Good discipline & time
management skills
– Here over summer
– Good programmer
– Intro graphics (or equiv)
– Hardware capable
– Strong math skills
– Intro perception
knowledge