Virtual Tailor [DEMO1] [DEMO2]

 Virtual Tailor is a freehand, pen-centric, sketch-based system for fast prototyping of 2D panels and garment design. An interactive draping and fitting visualization and evaluation system. Besides, Virtual Tailor is an interactive 3D visualization system for assembling garment panels and producing 3D garments based on material characteristics and geometric constraints. We develop an intelligent database to store and retrieve textile documentation and ensure the information flow in any kind of format.

A Randomized Marking Scheme for Continuous Collision Detection in Simulation of Deformable Surfaces
W.S.-K. Wong and G. Baciu,
VRCIA 2006, to appear
 Continuous collision detection techniques are applied extensively in the simulation of deformable surfaces, in particular for cloth simulation. Accurate contact information can be computed by using these techniques. Traditionally, for meshed surfaces, after collecting the triangle pairs that are potentially interacting, the feature pairs of these triangles are directly sent for the computation of collision information. Many feature pairs end up being processed repeatedly because a feature may be shared by more than one triangle. In this paper, we propose a randomized marking scheme to mark triangles and embed a \emph{feature filtering layer} (FFL) in the pipeline of continuous collision detection. The purpose of the FFL is to extract potentially interacting feature pairs according to the marking of the triangles. By applying the FFL each interacting feature pair is processed exactly one time for the computation of collision information. On average, the number of potentially interacting feature pairs reduces significantly after filtering. We have integrated the FFL in a cloth simulation system. Interactive rates can be achieved for complex draping simulation. [ Movie (mov) 9MB ]
OACM, (2006). This is the author¡¦s version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in PUBLICATION, {} http://doi.acm.org/

GPU-based Intrinsic Collision Detection for Deformable Surfaces
W.S.-K. Wong and G. Baciu,
Computer Animation and Virtual World,
vol. 16, number 3-4, 153-161.
 An Intrinsic Collision Detection Unit (ICDU) forms the bottom-most layer of a collision detection pipeline. The ICDU performs collision detection and computes collision information for primitive feature pairs of objects in a 3D dynamic environment. A significant amount of time can be spent by the ICDU during the collision detection process. In this paper, we extend the ICDU framework to take advantages of the computational power of programmable graphics processors (GPUs). Some components of the ICDU framework consist of time demanding and fine-grained tasks that can be implemented on GPUs. By employing the framework, collision information can be computed accurately, robustly and efficiently. Experimental results show that the proposed method greatly improves the performance of the ICDU. A collection buffer is proposed for the future enhancement of GPU-based collision detectors. [ Movie (avi) 19MB ]

Intrinsic Continuous Collision Detection for Deformable Meshes
W.S.-K. Wong and G. Baciu,
Research Journal of Textile and Apparel, vol. 9, number 1, 60-73.
 We propose an architecture for the intrinsic collision detection unit to perform collision detection for deformable triangular meshes, accurately, robustly and efficiently. We adopt a cache scheme which greatly improves the feature (e.g. point, edge and triangle) collision detection and thus improves the overall collision detection process. Our method handles numerical errors appropriately. Therefore, it accurately reports all the first contact points and collision information. Moreover, the method tracks collision orientations inherently so that proper action can be taken in order to avoid inter-penetrations. This method suits to meshes in a highly contact virtual environment in which the number of contact points is large. We illustrate an example of the applications of the method in cloth simulation.

Multi-Layer Deformable Surfaces
Very Complex Multi-layer Deformable Surfaces
Members: Wingo Sai-Keung WONG
Year 2004
 Very complex multi-layer deformable surfaces. The complex interaction between deformable surfaces is demonstrated. [ Movie (mov) 25.7MB ]

Four Glued Rectangular Pieces
 Four rectangular cloth pieces are glued together one by one. Complexity (including deformable surfaces only): 41, 760 triangles 21, 440 particles [ Movie (mov) 20.3MB ]

Garment with Long Fringes
 Fluttering fringes which are attached to a garment. [ Movie (mov) 8.42MB ]

Garment with Totally Attached Rings
 Soft rings are totally attached to a garment. Complexity (including deformable surfaces only): 22, 896 triangles 11, 790 particles [ Movie (mov) 17.1MB ]

Garment with Partially Attached Rings
 The dancing soft rings in the air. Complexity (including deformable surfaces only): 23, 184 triangles 12, 066 particles [ Movie (mov) 9.68MB ]

Complex
 Each deformable surface consists of 21, 600 triangles and 10, 980 particles. Total scene complexity: (including deformable surfaces only) 64, 800 triangles and 32, 940 particles. It can be easily to glue more deformable surfaces together and make the scene more complex. [ Movie (mov) 10.1MB ]

Different Spring Coefficients
 Fluttering garment and soft rings. Left image: small spring coefficient. Right image: large spring coefficient. [ Movie (mov) 13.6MB ]

Dynamics Interaction between Deformable Surfaces and Nonsmooth Objects
W.S.-K. Wong and G. Baciu,
Transactions on Visualization and Computer Graphics, vol. 11, number 3, 329-340.
 In this paper, we introduce new techniques that enhance the computational performance for the interactions between sharp objects and deformable surfaces. This is based on a time-domain predictor-corrector model. For this purpose we define a new kind of $(\pi, \beta, \mbf{I})$-surface. The partitioning of a deformable surface into a finite set of $(\pi, \beta, \mbf{I})$-surfaces allows us to prune a large number of non-colliding feature pairs. This leads to a significant performance improvement in the collision detection process. The intrinsic collision detection is performed in the time domain. Although it is more expensive compared to the static interference test, it avoids portions of the surfaces passing through each other in a single time step. In order to resolve all the possible collision events at a given time, a penetration-free motion space is constructed for each colliding particle. By keeping the velocity of each particle inside the motion space, we guarantee that the current colliding feature pairs will not penetrate each other in the subsequent motion. A static analysis approach is adopted to handle friction by considering the forces acting on the particles and their velocities. In our formulation, we further reduce the computational complexity by eliminating the need to compute repulsive forces. Movie Download QuickTime Movies [Entire Sequence [long version]: 49.3MB] : close-up and zoom out views [low quality] [Entire Sequence [short version]: 13.1MB] : [low quality, fast] [ 1. Slope closeup: 4.5MB ] [ Slope: 8.6MB ] [ 2. Nails closeup: 8.4MB ] [ Nails: 8.0MB ] [ 3. Sliding closeup: 14.0MB ] [ Sliding: 13.2MB ] [ 4. Bumpy closeup: 7.8MB ] [ Bumpy zoom out: 7.3MB ] [ 5. Draping closeup: 4.2MB ] [ Draping: 4.5MB ] [ 6. Windy closeup: 13.2MB ] [ Windy zoom out: 12.7MB ]

Complex Self-Interaction of Deformable Surface
 Complex interaction of a multi-ribbon. [ Movie (mov) 12.8MB ]

Skirt Draping and Fluttering
 Skirt draping and fluttering. [ Movie (mov) 5.5MB ]

Friction
 Object interaction with different friction coefficients. [ Movie (mov) 19.0MB ]

Fluttering Garment & Soft Rings
 Fluttering garment and soft rings. [ Movie (mov) 10.8MB ]

Piecewise Stably Sewing Process of Deformable Surfaces
Members: Wingo Sai-Keung WONG
Year: Sep 2004
 Stable, scalable, "fit onto" sewing process. A background stochastic wind blowing is activated. Realistic wrinkles ... NO ANCHORS ... [ Movie (mov) 10.8MB ]

Flag Simulation
Members: Wingo Sai-Keung WONG
Year: 2002
 Abstract: A spring-mass system is used for modeling a flag. The motion of the flag is under the effect of gravitational force and a virtual wind. There is no collision detection nor response enabled.

VRST'02 Demo Movies
Members: Wingo Sai-Keung WONG
Year: 2002
 Abstract: There are two clips. In one clipe there are four movies. Each movie is played twice. The movies are: (1) a U-shape surface with some fixed points falling over three half-sphere tables; (2) two carpets falling over three spheres; (3) a carpet falling over a female model with two hands flung out; (4) a carpet falling over a standing female model. In another clip, there are some snows flying under the effect of gravitational force and virtual wind. And also there is a carpet and its fringes are moving freely under the forces. Downloads: | Movie 1 | Movie 2 | Movie 3 | Movie 4 | Movie 5 | Movie 6 |

Motion Capture and Synthesis
Members: Iu Ka Chun Bartholomew
Year: 2001-2002
 Abstract: Motion capture is a technology in the 3D computer modeling to get the locus of a moving object into data that can be processed by 3D computer programs. One of the key drawbacks of motion capture is that it does not have the ability to handle post-processing of the captured data. Even though several commercial tools are already available to handle the post-processing, post-capture motion editing remains one of the most active research areas in the field of computer animation. One of the real challenges of motion editing is to create motion for the imaginary creatures. In this project, we first explore different techniques for editing motion and apply one of these techniques to implement a cross-platform motion editing system using OpenGL, C and C++.

City Modelling
Members: Sun Jing
Year: 2002
 Abstract: Here we propose a novel method to generate a virtual traffic network based on patterns and templates. Using 2D images as input maps, various road maps with different patterns could be produced. This traffic network generating model adjusts itself intelligently in order to avoid restricted geographical areas or urban developments. The generative model follows closely directions of elevation and connects road ends in ways that allow various types of breakpoints.

Surface Intersection
Members: KWOK Ki-Wan
Year: 2002
 Abstract: We propose a subdivision approach to compute the intersections between two surfaces of revolution. Each surface of revolution is subdivided into a series of co-axial bounded revolute quadrics and hence the intersection problem is reduced into computing the intersections between two revolute quadrics. This demo shows that in most cases our method is faster than the fastest currently known method which is an analytical based approach.