Abstract: In this paper, we present an analytic-iterative Inverse Kinematics (IK) method, called Sequential IK (SIK), that reconstructs 3D human full-body movements in real time. The input data for the reconstruction is the least possible (i.e., the positions of wrists, ankles, head and pelvis) in order to be usable within a low-cost human motion capture system that would track only these six features. The performance of our approach is compared to other well-known IK methods in reconstruction quality and computation time obtaining satisfactory results for both. The paper first describes how we handle the spine and the clavicles before offering a simple joint limit model for ball-and-socket joints and a method to avoid self-collisions induced by the elbow. The second part focuses on the algorithms comparison study.

Abstract: Starting from an input video, we replicate the manual technique of paint-on-glass animation. Motion maps are used to represent the regions where changes occur between frames. Edges are the key to identifying frame-to-frame changes, and a strong motion map is constructed from the edges in each frame, displaced by the motion vector. A second, weak motion map records the other pixels where there is significant movement between frames. These maps are used to generate the brush strokes necessary to convert one 'painted' frame into the next. Local gradient interpolation, based robustly on the edges, is used to determine the orientation of the brush strokes, and we avoid holes in the image by making additional strokes with smaller brushes. We also employ MSE data in evaluating temporal coherence between frames.

Abstract: Volumetric data, such as output from CT scans or laser range scan processing methods, often have isosurfaces that contain topological noise-small handles and holes that are not present in the original model. Because this noise can significantly degrade the performance of other geometric processing algorithms, we present a volumetric method that removes the topological noise and patches holes in undefined regions for a given isovalue. We start with a surface completely inside the isosurface of interest and a surface completely outside the isosurface. These surfaces are expanded and contracted, respectively, on a voxel-by-voxel basis. Changes in topology of the surfaces are prevented at every step using a local topology test. The result is a pair of surfaces that accurately reflect the geometry of the model but have simple topology. We represent the volume in an octree format for improved performance in space and time.

Abstract: Wang Tiles are constructed from four texture samples, arranged so they can always match a choice of other tiles at two edges. Because they are precomputed, Wang Tiles are a very efficient way to generate textures on the fly. But matching problems occur within tiles and at the corners of adjacent tiles. By replacing the edge-matching texture samples with a new sample in the center of the tile, and using the graph cut path-finding algorithm, we overcome these problems and introduce additional texture diversity. Our s-Wang Tiles are a stricter interpretation of the original Wang Tile design, and our tile set is also smaller than that required by @w-Tiles: only eight different tiles are required for a non-repetitive titling.

Abstract: Atmospheric binary mixtures such as tornado, sandstorm are common natural phenomena in our daily life. There are two fluid systems in these phenomena, which are air flow (wind field) and dust particle flow. Due to the complex mechanism of two fluid systems and the interaction between them, few works have been done on simulating these phenomena. In this paper, for the first time, we have simulated such two fluid phenomena under a unified framework by a Reynolds-average two-fluid model (RATFM) based on the Navier-Stokes equations. In RATFM, the air flow and dust particle flow are simulated accurately by two different Navier-Stokes equations, respectively. The interaction between two fluids is also simulated by introducing an interaction force. Then, a RATFM solver on GPU is designed to achieve fast simulation. In addition, multiple scattering effects of the participating media are considered for realistic rendering.

Abstract: In the present work we propose a simple and flexible fluid simulation method that enables us to perform one-way interactions of animated bodies with a coupled gas-liquid flow. This way we can animate flows in which not only the liquid but also the air is a performer. Our method allows the use of rigidly moving, articulated or deforming meshes. The paper shows how to do this practically, using a coupled level set and volume-of-fluid method. We also introduce to computer graphics a novel boundary condition, useful for open-field simulations. Animations of a swimmer in a pool, a hand scooping out water and a heart beating and spurting out either liquid or gas, showcase the strengths of our method.

Abstract: In this paper we present a novel volumetric shape from silhouette (SfS) algorithm based on a centripetal pentahedron model (pent-model). The pent-model is an object-centered volumetric model composed of a set of pentahedrons cut from the centripetal triangular pyramids, which together partition the 3D space. The SfS algorithm first computes the pyramids by constructing a geodesic sphere. These pyramids are then projected onto the image planes of all cameras. The intersections between the projected pyramids and the silhouettes, which are a set of hexagons, are computed. This process can be performed very efficiently with pre-computed polar silhouette graphs (PSGs) and reduced PSGs. The hexagons are then back-projected into the 3D space, where the intersections are calculated and the pent-model is derived. After that, a mesh surface model can be extracted by marching pentahedrons. Our algorithm has the combined advantages of robustness, speediness and preciseness. Experimental results based on both synthetic images and real photos are presented.

Abstract: We introduce a stable noise function with controllable properties. The well-known Perlin noise function is generated by interpolation of a pre-defined random number table. This table must be modified if user-defined constraints are to be satisfied, but modification can destroy the stability of the table. We integrate statistical tools for measuring the stability of a random number table with user constraints within an optimization procedure, so as to create a controlled random number table which nevertheless has a uniform random distribution, no periodicity, and a band-limited property.

Abstract: This paper studies the inside looking out camera pose estimation for the virtual studio. The camera pose estimation process, the process of estimating a camera's extrinsic parameters, is based on closed-form geometrical approaches which use the benefit of simple corner detection of 3D cubic-like virtual studio landmarks. We first look at the effective parameters of the camera pose estimation process for the virtual studio. Our studies include all characteristic landmark parameters like landmark lengths, landmark corner angles and their installation position errors and some camera parameters like lens focal length and CCD resolution. Through computer simulation we investigate and analyze all these parameters' efficiency in camera extrinsic parameters, including camera rotation and position matrixes. Based on this work, we found that the camera translation vector is affected more than other camera extrinsic parameters because of the noise of effective camera pose estimation parameters. Therefore, we present a novel iterative geometrical noise cancellation method for the closed-form camera pose estimation process. This is based on the collinearity theory that reduces the estimation error of the camera translation vector, which plays a major role in camera extrinsic parameters estimation errors. To validate our method, we test it in a complete virtual studio simulation. Our simulation results show that they are in the same order as those of some commercial systems, such as the BBC and InterSense IS-1200 VisTracker.

Abstract: The pre-integrated volume rendering technique is widely used for creating high quality images. It produces good images even though the transfer function is nonlinear. Because the size of the pre-integration lookup table is proportional to the square of data precision, the required storage and computation load steeply increase for rendering of high-precision volume data. In this paper, we propose a method that approximates the pre-integration function proportional to the data precision. Using the arithmetic mean instead of the geometric mean and storing opacity instead of extinction density, this technique reduces the size and the update time of the pre-integration lookup table so that it classifies high-precision volume data interactively. We demonstrate performance gains for typical renderings of volume datasets.