Published Work

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Adaptive extraction and visualization
of silhouette curves from volumetric datasets
An algorithm for near interactive silhouette extraction from volumetric data is presented. Trivariate tensor product B-spline functions are used to represent the data. An off-line phase that arranges the data in a lookup table is employed to improve the computation time during an interactive session. A subdivision scheme is employed to extract the silhouette curves from an implicit trivariate B-spline function. The produced results are smooth, high quality, silhouette curves when compared to voxel-based silhouettes extraction schemes. The conference version is given here.

This is a joint work with Gershon Elber.

Published: The Visual Computer, 20(4), 2004, pages 243-252

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.

This is a joint work with Gershon Elber.

Published: Computer Graphics Forum, 23(4) 2004, pages 727-739.


Real-time Incision Simulation Using Discontinuous Free Form Deformation

Surgical simulations with the aid of computers is a topic of increasingly extensive research. Real-time response and interactivity are crucial components of any such system and a major effort has been invested in finding ways to improve the performance of existing systems.

In this paper, we propose the use of a new variant of Free Form Deformations that supports discontinuities (DFFD) in complex real time surgical simulations. The proposed scheme can benefit from an a priori or, alternatively, interactive low resolution, physical simulation of the incision procedure that is encoded into the DFFD. The DFFD is then applied to the geometry of the tissue in hand, a two-dimensional skin shape or a three-dimensional volumetric representation, capturing the incision's shape as well as the behavior of the neighborhood geometry over time.

This is a joint work with Guy Sela and Gershon Elber.

Presented: The international Symposium on Medical Simulation June 2004, Cambridge, MA.
Published: Springer LNCS volume 3078 pages 114-123.


Discontinuous Free Form Deformation

Free Form Deformation (FFD) has become an acceptable design paradigm. Contemporary deformation tools let designers modify the geometry of the deformed model. This approach can be restrictive if the designer wants to incorporate holes or gaps into a model while deforming it into a different shape. This work presents a variant of FFD that would let the designer incorporate iso-parametric discontinuities into the deformation function. The input model is automatically split at these discontinuities, allowing the deformed model to reflect topological discontinuity changes.

We demonstrate the deformation algorithm using two different applications. The first application wraps a moving model around obstacles in a scene, splitting and then re-forming it. The second application works locally, enabling the end-user to insert arbitrarily shaped cuts into the surface of the model.

This is a joint work with Gershon Elber.

Published: The 12th Pacific Conference on Graphics and Applications, Seoul, Korea, 2004, pages 227-236.

GPU related publications

Most of my current research is focused on doing geometric-centric operations on the GPU.

Geometric Modeling on the GPU is less common then doing other general purpose computations such as image processing or computer vision. Only recently have this topic have captured the attention of researchers.



Pending papers