CGL Meeting Agenda

Wednesday, August 19th, 1998

Location:
DC 1304
Time:
1:30
Chair:
Wilkin Chau
:-|()
Member List

1. Adoption of the Agenda - additions or deletions

2. Coffee Hour

Coffee hour this week:
Jan Kautz
Coffee hour next week:
who?

3. Next meeting

Date:
Wednesday, August 26, 1998
Location:
DC 1304
Time:
1:30
Chair:
Blair Conard
:-)
Technical presentation:
Berj Bannayan
:-)

4. Forthcoming

Chairs:
  1. Bill Cowan (September 2nd)
    2. :-)
  2. Itai Danan (September 9th)
    3. :-)
  3. Erik Demaine (September 16th)
    4. :-)
Tech Presenters:
  1. Wilkin Chau (September 2nd) :-)
  2. Blair Conrad (September 9th) :-)
  3. Shalini Aggarwal (September 16th)
    4. :-)

5. Technical Presentation

Presenter:
Bill Cowan :-)
Title:
Dynamic Range Reproduction ?
Abstract:
Discussion of dynamic range reproduction based on Donald Greenberg's Siggraph paper will be given.

6. General Discussion Items

7. List of Action and Continuing Items

8. Director's Meeting

9. Seminars



DEPARTMENT OF COMPUTER SCIENCE
UNIVERSITY OF WATERLOO
SEMINAR ACTIVITIES

THEORY SEMINAR


                    - Wednesday, August 19, 1998

Alfredo Viola, Instituto de Computacion, Universidad de
la  Republica,  Montevideo,  Uruguay,  will  speak ``On
Combinatorial Aspects of Linear Probing Hashing''.


TIME:                3:30-4:30 p.m.

ROOM:                DC 1304



ABSTRACT

We  present  moment  analyses  and characterizations of
limit  distributions  for the construction cost of hash
tables under the linear probing strategy.

For  full tables, the construction cost has expectation
   3/2
O(n   )  , the standard deviation is of the same order,
and  a  limit  law  of  the Airy type holds. For sparse
tables with a fixed filling ratio strictly smaller than
1, the construction cost has expectation O(n), standard
deviation  O(square root of n),  and a limit law of the 
Gaussian type holds.

We  conclude with a brief presentation of combinatorial
relations with other problems leading to Airy phenomena
(such as graph connectivity, tree inversions, tree path
length, or area under excursions).

This  is joint work with Philippe Flajolet and Patricio
Poblete.

-------------------------------------------------------------------

Advanced Image Synthesis
Spring 1998

What:
  CS788 students are required to give formal public presentations 
  describing and summarizing their projects and the related theory. 
  Presentations will be 20 minutes in length, with 10 minutes for 
  questions and discussion.

  Anyone with an interest is invited to attend.   Please note that 
  the talks will be presented on two separate dates, August 21st 
  and August 27th.

When:
  Aug 21, 1998 
  1:30---2:00
Where:      
  DC 1304
Who:

  Carsten Whimster 
    Interactive Global Illumination

	Hardware rendering, augmented with shadows, can be used to 
    accelerate the last two bounces of a light path tracing global 
    illumination algorithm. An implementation of this algorithm was 
    performed, using a scattering of a few hundred infinitesimal 
    area sources and the shadow volume reconstruction algorithm.

When:
  Aug 27, 1998 
  1:00---3:30
Where:
  DC 1304
Who:

  (1:00) Ian Stewart
	Acceleration of General Implicit Surface Raycasting

	The interval Newton method can be used to robustly find all 
    roots along a ray through arithmetically computable functions, 
    which can be used to render general implicit surfaces. 
    Unfortunately, naive interval analysis is relatively slow. 
    Fortunately, there are ways to greatly speed up the process 
    that do not sacrifice robustness.

  (1:30) Jan Kautz
    Interactive Rendering with Arbitrary Reflectances

	Bidirectional reflectance distributions are general models of 
    surface reflectance. They can be decomposed into sums of 
    separable functions by finding the SVD of a sampled matrix 
    representation of the BRDF. This compressed representation of 
    the BRDF lets us use hardware texture mapping, compositing, 
    and accumulation operations to reconstruct the reflectance.

  (2:00) Caroline Kierstead
    Simulation of Reflectance due to Subsurface Scattering

	Many important real materials, such as skin, leaves, and 
    painted surfaces, are composed of multiple layers of 
    semitranslucent materials, each of which scatters, absorbs, 
    and reflects light. A Monte Carlo simulator was built to 
    estimate the bidirectional reflectance distributions from 
    such surfaces. This was compared with the analytic, 
    first-bounce solution.

  (2:30) Shalini Aggarwal
    Rendering and Modelling with A-Patches

	A-patches are implicit surfaces based on Bezier tetrahedra 
    that are guaranteed to contain a single-sheeted algebraic 
    surface patch where all line segments between one vertex/face 
    pair intersect the patch exactly once. Under such conditions 
    the patches can be quickly and robustly rendered using a scalar 
    root solver. A-patches were analyzed with blossoming techniques, 
    and used to fit surfaces to parametric scattered data.

  (3:00) Eric Hall
    Texture Mapping Pasted Surfaces

	Pasted surfaces can be used to adaptively and efficiently add 
    detail to a spline surface. However, due to the lack of a 
    global surface parameterization, texture maps on these 
    surfaces can exhibit discontinuities. Various techniques were 
    explored to obtain a suitable continuous global 
    parameterization.

For More Information:

http://www.cgl.uwaterloo.ca/~mmccool/cs788/

10. Lab Purification