The following program is also available in PostScript format. The PostScript file is to be printed double-sided
on A4 paper, and folded into three columns with INVITATION and the digit
"6" on the exposed columns.
| Time | Speaker | Title | Abstract |
|---|---|---|---|
| 8:30 | REFRESHMENTS | ||
| 9:00 | Shachar Fleishman School of Computer Science Tel-Aviv University |
Bilateral Mesh Denoising |
We present an anisotropic mesh denoising algorithm that is
effective, simple and fast. This is accomplished by filtering
vertices of the mesh in the normal direction using local
neighborhoods. Motivated by the impressive results of bilateral
filtering for image denoising, we adopt it to denoise 3D meshes;
addressing the specific issues required in the transition from
two-dimensions to manifolds in three dimensions. We show that the
proposed method successfully removes noise from meshes while
preserving features. Furthermore, the presented algorithm excels
in its simplicity both in concept and implementation.
Joint work with Iddo Drori and Daniel Cohen-Or. |
| 9:30 | Yaron Ostrovsky-Berman
| Tolerance Envelopes of Parametric Planar Part Models |
We present a framework for modeling parametric variation in
planar parts and for efficiently computing approximations of their
tolerance envelopes. Part features are specified by algebraic equations
defining their position and shape as a function of parameters whose nominal
values vary along tolerance intervals. Their tolerance envelopes model
perfect form Least and Most Material Conditions (LMC/MMC). We derive
geometric properties of the tolerance envelopes and describe efficient
algorithms for computing first-order linear approximations with successive
accuracy. We show that the tolerance envelope of a parametric arc-line
polygonal part with $n$ features has $O(nk^2)$ segments and can be computed
in $O(nk^2 \log k)$ time, where $k$ is the maximum number of non-zero
partial feature functions derivatives evaluated at nominal parameter
values. Our implementation shows that the algorithms are practical on part
models with tens of parameters.
Joint work with Leo Joskowicz.
|
| 10:00 | Sagi Schein
Dept. of Computer Science Technion |
Placement of Deformable Objects |
With the increasing complexity of photo-realistic scenes, the
question of building and placing objects in three-dimensional
scenes is becoming ever more difficult. While the question of
placement of rigid objects has captured the attention of researchers
in the past, this work presents an intuitive and interactive scheme
to properly place deformable objects with the aid of free-form
deformation tools. The presented scheme can also be used to animate
the locomotion of non-rigid objects, most noticeably animals, and
adapt the motion to arbitrary terrain.
The automatic construction of our free-form deformation tool is
completely hidden from the end user, and hence, circumvents the
difficulties typically faced in manipulating these deformation
functions. Further, a precise bound on the error that is introduced
by applying free-form deformations to polygonal models is presented,
along with an almost-optimal adaptive refinement algorithm to achieve
a certain accuracy in the mapping.
Joint work with Gershon Elber. |
| 10:30 | COFFEE BREAK | ||
| 11:00 | Dani Brunstein
Dept. of Computer Science Technion |
Animating a Camera for Viewing a Planar Polygon |
Many applications, ranging from visualization applications (such as
architectural walkthroughs) to robotic applications (such as
surveillance),
could benefit from an automatic camera trajectory planner. This talk
shows an algorithm for dealing with that problem. We have automated the
process of inspecting the outside of a simple two-dimensional polygon,
given a few user parameters. Our algorithm preprocesses the polygon using
Visibility-Graph-like concepts, and creates a data structure for each
polygon edge. From these structures, "good" camera zones are computed.
Natural cubic splines are then used to create a closed camera trajectory
that passes solely inside the zones. An iterative process refines the
trajectory by minimizing a cost function until it converges to the
optimal result.
Joint work with Gill Barequet and Craig Gotsman. |
| 11:30 | Sagi Katz Dept. of Electrical Engineering Technion |
Hierarchical Mesh Decomposition Using Fuzzy Clustering and Cuts |
Cutting up a complex object into simpler sub-objects is a fundamental
problem in various disciplines. In image processing, images are segmented
while in computational geometry, solid polyhedra are decomposed. In
recent years, in computer graphics, polygonal meshes are decomposed into
sub-meshes. In this paper we propose a novel hierarchical mesh
decomposition algorithm. Our algorithm computes a decomposition into the
meaningful components of a given mesh, which generally refers to
segmentation at regions of deep concavities. The algorithm also avoids
over-segmentation and jaggy boundaries between the components. Finally,
we demonstrate the utility of the algorithm in control-skeleton
extraction.
Joint work with Ayellet Tal |
| 12:00 | Alon Lerner School of Computer Science Tel-Aviv University |
Breaking the Walls: Scene Partitioning and Portal Creation |
In this talk we revisit the cells-and-portals visibility methods, originally
developed for the special case of architectural interiors. We define an
effectiveness measure for a cells-and-portals partition, and introduce a two-
pass algorithm that computes a cells-and-portals partition. The algorithm uses
a simple heuristic that creates short portals as a means for generating an
effective partition. The input to the algorithm is a set of half edges in 2D,
that can be extracted from a complex polygonal model. The first pass of
the algorithm creates an initial partition, which is then refined by the second
pass. We show that our method creates a partition that is more effective than
the common BSP partition, even when the latter is further refined with the
application of our second pass. Our cells-and-portals algorithm is designed to
deal with arbitrarily oriented walls. The algorithm also supports outdoor
scenes, where the vertical walls of the buildings serve as occluders and
portals are extended above the buildings. We show that the extended portals al-
low an output-sensitive rendering of large urban scenes. Finally, since our two-pass method is fully automatic and local, it supports incremental changes of
the model by locally recomputing and updating the partition. We call our
method "Breaking the Walls" (BW) since it breaks out of indoor scenes to
outdoor scenes, and allows walls to be broken interactively, with an instant
updating of the partition.
Joint work with Yiorgos Chrysanthou and Daniel Cohen-Or. |