|
October 1:
| 8:30–9:30 |
Meet & Greet / Continental Breakfast
|
| 9:30–9:45 |
Greg Ward & Katja Doerschner, Introduction
|
9:45–10:25
PPT
PDF |
Roland Fleming, Max Planck Institute for Biological
Cybernetics, Tuebingen, German
"Visual Perception of Surface
Material"
Different materials such as silk, bronze and marmalade have
distinctive visual appearances. Human observers are remarkably
adept at recognizing materials across a wide range of viewing
conditions and we are only just beginning to work out how. What
gives a material its characteristic 'look'? What cues does the
visual system use to identify materials? How can we leverage the
assumptions made by the visual system to improve computer graphics?
I will review some of our research on the perception of material
properties such as gloss, translucency and refractive index that
attempts to shed some light on these questions. Ill talk about
how illumination and 3D geometry interact with material perception,
and discuss the role of various image statistics (e.g. intensity
histogram, amplitude spectrum) in the visual estimation of material
attributes. Ill then show one application in which we exploit the
heuristics made by the visual system to enable illusory
modifications of material appearance in photographs.
|
| 10:30–10:50 |
Coffee Break
|
10:50–11:20
PPT
PDF |
Yu Sheng, Rensselaer Polytechnic Institute, Troy,
NY
"Comparing an interactive hybrid global
illumination method with Radiance"
Complex fenestration systems (CFS) can be used to redirect intense
illumination from the sun to more evenly illuminate an architectural
space and thus reduce the lighting needs of buildings. However,
standard distribution of Radiance does not support rendering of
CFS or arbitrary BRDF/BTDF material data. In this talk, we present
an interactive rendering system for architectural design which
simulates a CFS based on 4D Bidirectional Transmission Distribution
Function (BTDF) data. We use a hybrid method of shadow volumes for
direct illumination and radiosity for indirect illumination to
achieve interactive rendering rates.
Our system is appropriate for use in schematic design: an early
stage of the architectural design process where scale, appearance,
and adjacencies of an evolving design are explored. We demonstrate
our system on several models inspired by field observations and the
designs of architecture students we have consulted during the
development of this project.
|
11:20–11:50
PPT
PDF |
Bei Xiao, University of Pennsylvania, Philadelphia,
PA
"Effect of test patch location on color
appearance, in the context of 3D objects"
Bei Xiao (1) and David Brainard (2)
(1) Department of Neuroscience, School of Medicine, University of
Pennsylvania, Philadelphia, PA, 19104, USA. (2) Department of
Psychology, University of Pennsylvania, Philadelphia, PA, 19104,
USA.
The light reflected from different locations on a single object can
vary enormously. This variation is enhanced when the material
properties of the object are changed from matte to glossy. Yet
humans have no trouble perceiving an object as having a unified
color. We conducted a psychophysical experiment to study how people
perceive the color of different parts of an object. Observers viewed
graphics simulations of a three-dimensional scene containing two
objects, test and match (generated with Radiance in conjunction
with custom software that provided full spectral rendering). The
test object was a soccer ball that had one colored hexagonal face
(test patch). Observers were asked to adjust the color appearance
of a match sphere to the test patch. The match sphere was always
matte, while we varied the surface gloss of the entire soccer ball
(including the test patch). The test patch could be located at
either an upper or lower location on the soccer ball. The data
show that there is an effect of test patch location on observers'
color matching, but this effect is small compared to the physical
change in the average light reflected from the test patch across
the two locations. In addition, we found that observers exhibit
stability of color perception of the test patch in the face of
variation of surface gloss.
|
| 12:00–1:30 |
Lunch
|
| 1:30–2:30 |
Gary Meyer, Victoria Interrante, University of
Minnesota, Department of Computer Science
Digital Design Consortium and VR lab
tour/demos
|
2:30–3:15
PPT
PDF |
Greg Ward, Anyhere Software, Albany, CA
Tutorial: "Image-based
Lighting"
Image-based lighting (IBL) is a set of techniques originated by Paul
Debevec for incorporating synthetic objects into real-world scenery
www.debevec.org. IBL is widely used by the movie industry for
special effects production, and offers some interesting
possibilities for daylight simulation as well. In this tutorial,
Greg will demonstrate how easy it is to capture a high dynamic-range
environment map (a.k.a. a "light probe") using a standard
digital camera and use it to render synthetic objects into a
background plate with the help of Photosphere and the
"mksource" program. We will discuss how other
researchers, such as Santiago Torres, have employed IBL and
Radiance for daylighting simulation.
|
| 3:15–3:30 |
Coffee Break
|
3:30–4:00
PPT
PDF |
Zack Rogers, Architectural Energy Corporation,
Boulder, CO
Tutorial: "Sensor Placement + Optimization
Tool (SPOT) Update"
This talk will present recent updates to the Sensor Placement +
Optimization Tool software that acts as a front-end interface to
Radiance. SPOT has grown to provide more detailed electric lighting
and annual daylighting analysis as well as providing photosensor
control analysis. The focus of the presentation will be on the new
features of the software and a case study will be presented of a
project in which we used SPOT to help design a daylight responsive
control system. The talk will be 25 minutes followed by a question
and answer period.
|
| 6:30–7:30 |
Reception
|
| 7:30–10:30 |
Banquet
|
October 2:
| 8:30–9:00 |
Continental Breakfast
|
9:00–10:00
PPT
PDF |
Zack Rogers, Architectural Energy Corporation,
Boulder, CO
"Experiences with Radiance in Daylighting
Design, Part III"
Zack Rogers, Galen Burrell and Jennifer Scheib, Architectural
Energy Corporation
This talk will present some of the Radiance modeling Architectural
Energy Corporation has done in support of our Daylighting Design
Consulting work, focusing on the various ways we have used Radiance
to guide the design process. Radiance has proved to be extremely
effective in analyzing and visualizing daylighting designs,
allowing numerous daylighting design alternatives to be explored
beforehand, informing and guiding the daylighting design decisions
of a project. The types of daylighting design projects that will
be highlighted vary widely and include schools, laboratories,
offices, museums, atriums, and others. The focus of the
presentation will be on new work that has occurred since the
Montreal radiance conference in 2005.
The talk will be broken into three-20 minute sections, one section
given by each of the presenters followed by a brief question and
answer period.
|
| 10:00–10:25 |
Coffee break
|
10:25–10:50
MOV
PDF |
Greg Ward, Anyhere Software, Albany, CA
"Utilizing BTDF Window Data"
This talk presents some new ideas and software for exploiting
measured and simulated bidirectional transmittance distribution
function (BTDF) data in Radiance. Programs and standards for
providing BTDF data are emerging (e.g., LBNL Window 6), and we
wish to take advantage of it in our simulations. Two approaches
will be presented, one geared towards traditional daylight
simulation and rendering and the other towards annual calculations.
The first approach resembles mkillum but without the usual
restrictions, since BTDFs can represent virtually any complex
fenestration type. The second approach requires two passes of
rtcontrib, one to account for the building exterior, and the other
for the interior. This fully separates illumination from geometry
and permits time-based fenestration controls to be simulated
efficiently. As this constitutes work in progress, suggestions
will be most appreciated.
|
10:50–11:20
PPT
PDF |
Daniel Lichtman, University of Pennsylvania,
Philadelphia, PA
"RenderToolbox: A MATLAB Toolkit for
Hyperspectral Rendering with Radiance and PBRT"
Daniel P. Lichtman, Bei Xiao, David H. Brainard
We describe a set of Matlab software tools, the RenderToolbox, that
aid in the modeling and rendering of images for use in
psychophysical experiments. The toolbox, which we are
making freely available, has several important features.
First, it allows the user to model scenes in the popular
Maya software package and export these into the remainder
of the rendering pipeline. Second, although the toolbox
inherits the scene geometry from the Maya modeler, it
allows the user to associate full spectral reflectance
functions and parametric BRDFs with each object, and full
spectral power distributions with each illuminant. The toolbox
then parses the scenes and associated reflectance/illuminant
parameters and passes these to either of two renderers. These
are Radiance and Physically Based Rendering Tools (PBRT). It
invokes the renderers on a wavelength-by-wavelength basis to
produce a hyperspectral image of the scene. The fact that the
toolbox transparently supports two renderers allows easy comparison
of their performance. In addition, the toolbox is configured to make
it easy to re-render the same scene geometry with different choices
of reflectance/illuminant parameters. Fourth, the package provides
support for converting the hyperspectral image to standard color
representations. Finally, the package supports parallel rendering
of the separate wavelength images if a computer cluster is
available. Several example scenes are included with the toolbox
to demonstrate its use and to compare the two renderers'
performance. The simplest example, a uniformly reflective surface
and a single point-light source, yields two nearly identical images.
Each of these matches an analytical prediction based on the light's
spectral power distribution and surface's reflectance function. A
second example scene includes a single sphere with uniform
reflectance under a distant point-light source. Again, images
rendered by Radiance and PBRT are well-matched to each other
and to the directly calculated image based on the Ward model
of surface reflectance. The close agreement of the two renderers
with each other and with direct calculations for simple scenes
provides added confidence that each renderer is doing a good job
simulating physical light flow.
|
11:20–12:00
PDF |
Susan Ubbelohde, Loisos + Ubbelohde Associates,
Oakland, CA
"Daylighting in Practice: Radiance and the
Design Process"
Loisos + Ubbelohde is a consulting and design firm specializing in
sustainable architecture. Our consulting work focuses on advanced
daylighting design and performance, energy modeling and alternative
energy sources. In practice, the use of tools such as Radiance and
physical models is never as direct and linear as theory might
assume. Rather, our use of design and evaluation tools is
continually adapted to the design direction of the project,
the questions posed by the architects, the tradeoffs and
negotiations necessary with mechanical, structural, electrical
engineers, lighting designers and interior designers on the design
team, and the goals and concerns of the building owners and the
requirements of outside agencies such as the US Green Building
Council. We will present a range of recent projects, both consulting
projects and design projects, discussing our use of modeling tools
in the projects.
|
| 12:00–1:30 |
Lunch
|
1:30–2:30>
PPT
PDF |
Greg Ward, Anyhere Software, Albany, CA
Tutorial: "Improved Color Rendering with
RGB"
Accurate color rendering requires the consideration of many samples
over the visible spectrum, and advanced rendering tools developed by
the research community offer multispectral sampling towards this
goal. However, for practical reasons including efficiency, white
balance, and data demands, Radiance still employs a simple RGB
model in its lighting calculations. Applied naively, this can
result in colors that are qualitatively different from the correct
ones. In this tutorial, we demonstrate two independent and
complementary techniques for improving RGB rendering accuracy
in Radiance without impacting calculation time: spectral
prefiltering and color space selection. Spectral prefiltering
is an obvious but overlooked method of preparing input colors
for a conventional RGB rendering calculation, which achieves
exact results for the direct component, and very accurate results
for the interreflected component when compared with full-spectral
rendering. In particular, we demonstrate the merits of a particular
color space transform that has emerged from the research community
as the best performer in computing white point adaptation under
changing illuminants: the Sharp RGB space.
|
| 2:30–2:45 |
Coffee
|
2:45–3:15
PPT
PDF
MOV |
Katja Doerschner, Department of Psychology, University of Minnesota,
Minneapolis, MN
"Perceived Shininess and Rigidity — Measurements of Shape-Dependent
Specular Flow of Rotating Objects"
Katja Doerschner (1), Paul Schrater (1,2), Dan Kersten (1)
(1) Department of Psychology, University of Minnesota , (2) Department of
Computer Science, University of Minnesota
Specular flow provides useful constraints when estimating an object's shape
(Roth & Black 2006, Fleming et al. 2003). We tested experimentally whether
human observers can exploit these constraints when judging the rigidity and
shininess of rotating specular superellipsoids of varying
corner-roundedness. Our results indicate that observers perceived
more-rounded shapes (ellipsoids) less rigid and less shiny than cuboidal
shapes. We currently explore whether observers' perceptions correlate with
the characteristics of the image velocity distribution that these rotating
objects generate.
|
End of workshop
|
|
