Relighting Forest Ecosystems
Abstract
Real-time cinematic relighting of large, forest ecosystems remains
a challenging problem, in that important global illumination effects,
such as leaf transparency and inter-object light scattering, are
difficult to capture, given tight timing constraints and scenes
that typically contain hundreds of millions of primitives.
A solution that is based on a lattice-Boltzmann method is suggested.
Reflectance, transmittance, and absorptance parameters are
taken from measurements of real plants
and integrated into a parameterized, dynamic global illumination model.
When the model is combined with fast shadow rays, traced on a GPU,
near real-time cinematic relighting is achievable
for forest scenes containing hundreds of millions of polygons.
The paper appears in
Proc. 5th Int. Symp. on Visual Computing,
(ISVC 2009), Las Vegas, Nevada, November, 2009, published as
G. Bebis et al. (Eds.): ISVC 2009, Part I, LNCS 5875, pp. 55-66,
Springer, Heidelberg (2009), copyright Springer-Verlag;
full paper (.pdf): Relighting Forest Ecsosystems
The original publication is available at www.springerlink.com.
Virtualizing High-Performance Graphics Cards for
Driver Design and Development
Abstract
Operating system virtualization tools such as VMWare, XEN,
and Linux KVM export only minimally capable SVGA graphics adapters.
This paper describes the design and implementation of a system
that virtualizes high-performance graphics cards of arbitrary design
to support the construction of authentic device drivers.
Drivers written for the virtual cards can be used verbatim,
without special function calls or kernel modifications, as
drivers for real cards, should real cards of the same design exist.
The applications of the system include both instruction
in device driver design and allowing device driver design to proceed in
parallel with new hardware development.
The paper appears in
Proc. 19th Annual Int. Conf. of the IBM Centers for
Advanced Studies (CASCON 2009), Toronto, Canada, November, 2009.
full paper (.pdf): Virtualizing High-Performance Graphics Cards for Driver Design and Development
A Lighting Model for Fast Rendering of Forest Ecosystems
Abstract
Real-time rendering of large-scale, forest ecosystems remains a
challenging problem, in that important global illumination effects,
such as leaf transparency and inter-object light scattering, are difficult
to capture, given tight timing constraints and models that
typically contain hundreds of millions of primitives. This paper
proposes a new lighting model, adapted from a model previously
used to light convective clouds and other participating media, together
with a distribution of ray processing across multiple GPUs,
in order to achieve these global illumination effects while maintaining
near real-time performance. The lighting model is based on a
lattice-Boltzmann method in which reflectance, transmittance, and
absorptance parameters are taken from measurements of real plants.
The lighting model is solved as a pre-processing step and requires
only seconds on a single GPU. The ray tracing engine uses the well known
short-stack algorithm, due to Horn, Sugerman, Houston, and
Hanrahan. Both the pre-processing step and the ray tracing engine
make extensive use of NVIDIA's Compute Unified Device Architecture (CUDA).
The paper appears in
Proc. IEEE/EG Symposium on Interactive Ray Tracing (RT08),
Los Angeles, California, August, 2008, pp. 99 - 106, and back cover,
Copyright IEEE.
full paper (.pdf): A Lighting Model for Fast Rendering of Forest Ecosystems
Convective Clouds
Abstract
A new technique for rendering convective clouds is suggested. The technique
uses two lattice-Boltzmann (LB) models, one for generating the spatial and
temporal distribution
of water density and the other for photon transport,
that is, lighting the
water density with correct anisotropic scattering.
The common LB structure is easily mapped
to parallel execution environments such as a GPU or multiple
CPUs connected via the Message Passing Interface (MPI),
thereby providing sub-minute execution times
on commodity hardware.
The paper appears in
Natural Phenomena 2007 (Proc. of the Eurographics Workshop on Natural Phenomena),
Prague, Czech Republic, September, 2007, pp. 23 - 30, 83, and back cover,
Copyright The Eurographics Association and Blackwell Publishing, UK.
full paper (.pdf): Convective Clouds
τέχνη: Trial Phase for the New Curriculum
Abstract
The τέχνη project, which
provides an unusual alternative to the standard design of the
computing curriculum for the bachelor's degree in computer science,
is now entering full-scale implementation at Clemson University.
The approach relies extensively on problem-based instruction,
computer graphics, and the notion of cognitive apprenticeship.
The novelty arises from the magnitude and origin
of the problems to be integrated into the curriculum and the
breadth of impact across the curriculum. The first
three courses in the new curriculum are now being taught.
The design of each course is described,
and preliminary assessments from earlier trial sessions of
the first two courses are offered.
The paper appears in Proc. ACM SIGCSE Tech. Symp.
on Computer Science Education (SIGCSE 2007)
, Covington, Kentucky, March, 2007,
pp. 415 - 419, Copyright ACM.
full paper (.pdf): τέχνη: Trial Phase for the New Curriculum
Re-Coloring Images for Gamuts of Lower Dimension
Abstract
Color images have a gamut that typically spans three dimensions. Nevertheless,
several important applications, such as the creation of grayscale images
for printing and the re-coloring of images for color-deficient viewers,
require a reduction of gamut dimension. This paper describes a technique
for preserving visual detail while reducing gamut dimension. The
technique is derived by focusing on the problem of converting color
images to grayscale. A straightforward extension is then provided that
allows re-coloring images for color-deficient viewers. Care is taken so
that the resulting images remain within the available gamut and visual
artifacts are not introduced.
The paper appears in
Computer Graphics Forum,
25:3 (2005), pp. 423 - 432, Copyright The Eurographics Association and Blackwell Publishing, UK.
full paper (.pdf): Re-Coloring Images for Gamuts of Lower Dimension
Detail Preserving Reproduction of Color Images for Monochromats and Dichromats
Abstract
An algorithm that transforms color to grayscale preserves
image detail by maintaining distance ratios during the
reduction process. An extension of the transformation
can aid color-deficient observers.
The paper appears in IEEE Computer Graphics
& Applications, Special Issue on Smart Depiction for Visual Communication,
25:3 May-June, 2005, pp. 22 - 30, Copyright IEEE.
full paper (.pdf): Detail Preserving Reproduction of Color Images for Monochromats and Dichromats
Lattice-Boltzman Lighting
Abstract
A new technique for lighting participating media is suggested.
The technique is based on the lattice-Boltzmann method, which is
gaining popularity as alternative to finite-element methods
for flow computations, due to its ease of implementation and ability
to handle complex boundary conditions. A relatively simple, grid-based
photon transport model is postulated and then shown to describe, in the limit,
a diffusion process. An application to lighting clouds is provided,
where cloud densities are generated by combining two well-established
techniques. Performance of the new lighting technique is not real-time,
but the technique is highly parallel and does offer an ability to
easily represent complex scattering events. Sample renderings are
included.
The paper appears in Rendering Techniques 2004
(Proc. Eurographics Symposium on Rendering), Norrköping,
Sweden, June, 2004, pp. 355 - 362, Copyright The Eurographics Association.
full paper (.pdf): Lattice-Boltzmann Lighting
τέχνη: A First Step
Abstract
A new approach to the design of the computing curriculum
for a Bachelor of Arts degree is described. The approach
relies extensively on problem-based instruction and computer
graphics. The novelty arises from the magnitude and origin
of the problems to be integrated into the curriculum and the
breadth of the impact across the curriculum. Results from a
trial course, the first experiment with the new approach, are described.
The course, Tools and Techniques for Software Development,
is a sophomore-level course in programming methodology.
Construction of a ray-tracing system (for generating synthetic
images) was the vehicle chosen for the instruction.
The paper appears in Proc. ACM SIGCSE Tech. Symp.
on Computer Science Education (SIGCSE 2004)
, Norfolk, Virginia, March, 2004,
pp. 125 - 129, Copyright ACM.
full paper (.pdf): τέχνη: A First Step
geist@cs.clemson.edu