We present an innovative modeling and rendering primitive, called the O-buffer, for sample-based graphics, such as images, volumes and points. The 2D or 3D O-buffer is in essence a conventional image or a volume, resp...
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We present an innovative modeling and rendering primitive, called the O-buffer, for sample-based graphics, such as images, volumes and points. The 2D or 3D O-buffer is in essence a conventional image or a volume, respectively, except that samples are not restricted to a regular grid. A sample position in the O-buffer is recorded as an offset to the nearest grid point of a regular base grid (hence the name O-buffer). The offset is typically quantized for compact representation and efficient rendering. The O-buffer emancipates pixels and voxels from the regular grids and can greatly improve the modeling power of images and volumes. It is a semi-regular structure which lends itself to efficient construction and rendering. Image quality can be improved by storing more spatial information with samples and by avoiding multiple resamplings and delaying reconstruction to the final rendering stage. Using O-buffers, more accurate multi-resolution representations can be developed for images and volumes. It can also be exploited to represent and render unstructured primitives, such as points, particles, curvilinear or irregular volumes. The O-buffer is therefore a uniform representation for a variety of graphics primitives and supports mixing them in the same scene. We demonstrate the effectiveness of the O-buffer with hierarchical O-buffers, layered depth O-buffers, and hybrid volume rendering with O-buffers.
We propose methods to accelerate texture-based volume rendering by skipping invisible voxels. We partition the volume into sub-volumes, each containing voxels with similar properties. Sub-volumes composed of only voxe...
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We propose methods to accelerate texture-based volume rendering by skipping invisible voxels. We partition the volume into sub-volumes, each containing voxels with similar properties. Sub-volumes composed of only voxels mapped to empty by the transfer function are skipped. To render the adaptively partitioned sub-volumes in visibility order, we reorganize them into an orthogonal BSP tree. We also present an algorithm that computes incrementally the intersection of the volume with the slicing planes, which avoids the overhead of the intersection and texture coordinates computation introduced by the partitioning. Rendering with empty space skipping is 2 to 5 times faster than without it. To skip occluded voxels, we introduce the concept of orthogonal opacity map, that simplifies the transformation between the volume coordinates and the opacity map coordinates, which is intensively used for occlusion detection. The map is updated efficiently by the GPU. The sub-volumes are then culled and clipped against the opacity map. We also present a method that adaptively adjusts the optimal number of the opacity map updates. With occlusion clipping, about 60% of non-empty voxels can be skipped and an additional 80% speedup on average is gained for iso-surface-like rendering.
We present a simple and linear 3D cellular automata approach for animating the behaviors of viscous flow volumes in virtual environments. An accurate modeling of fluid flow usually requires complicated physical simula...
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We present a simple and linear 3D cellular automata approach for animating the behaviors of viscous flow volumes in virtual environments. An accurate modeling of fluid flow usually requires complicated physical simulations. In this paper, we concentrate on the behaviors of highly viscous fluids, such as wax, lava, plastic, metal, chocolate, etc. We animate the smooth behaviors of viscous fluid based on a local 3D cellular automata. The dynamic changing volume data is rendered directly on a VolumePro board or texture mapping hardware to achieve an interactive speed.
We present a simple, linear 3D cellular automata approach for animating the melting process of solid volumetric models. Accurate modelling of object melting usually requires complicated physical simulations of heat tr...
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We present a simple, linear 3D cellular automata approach for animating the melting process of solid volumetric models. Accurate modelling of object melting usually requires complicated physical simulations of heat transfer and phase transition from solid to liquid. Instead, we propose a simplified model to describe the melting behaviors of highly viscous objects, such as wax, lava, plastic, metal and chocolate. We simulate the process by which a volumetric solid transforms into a viscous liquid as the amount of heat it accumulates on its surface reaches a certain temperature. We then animate smooth fluid behavior using a cellular automata. The dynamic volume data is rendered directly on texture mapping hardware to achieve an interactive speed.
We explore real time volume rendering of multichannel data for volumes with color and multimodal information. We demonstrate volume rendering of the visible human male color dataset and photorealistic rendering of vox...
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We explore real time volume rendering of multichannel data for volumes with color and multimodal information. We demonstrate volume rendering of the visible human male color dataset and photorealistic rendering of voxelized terrains, and achieve high quality visualizations. We render multimodal volumes utilizing hardware programmability for accumulation level mixing, and use CT and MRI information as examples. We also use multiboard parallel/distributed rendering schemes for large datasets and investigate scalability issues. We employ the VolumePro 1000 for real time multichannel volume rendering. Our approach, however, is not hardware-specific and can use commodity texture hardware instead.
We present a novel surface reconstruction algorithm which can directly reconstruct surfaces with different levels of smoothness in one framework from height fields using 3D discrete grid ray tracing. Our algorithm exp...
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We present a novel surface reconstruction algorithm which can directly reconstruct surfaces with different levels of smoothness in one framework from height fields using 3D discrete grid ray tracing. Our algorithm exploits the 2.5D nature of the elevation data and the regularity of the rectangular grid from which the height field surface is sampled. Based on this reconstruction method, we also develop a hybrid rendering method which has the features of both rasterization and ray tracing. This hybrid method is designed to take advantage of GPUs newly available flexibility and processing power.
Currently, there is no reliable method to accurately predict the outcome of breast reconstruction for an individual patient prior to surgery. To address this limitation, we are developing a simulation system capable o...
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Currently, there is no reliable method to accurately predict the outcome of breast reconstruction for an individual patient prior to surgery. To address this limitation, we are developing a simulation system capable of rendering patient-specific predictions of the post-operative breast shape. Such a system for the planning of breast reconstructive surgery will greatly enhance patient prognosis. In this paper, we present our computer simulations representing the reconstructed breast using idealized and realistic geometric models.
We introduce a general technique for "colorizing" greyscale images by transferring color between a source, color image and a destination, greyscale image. Although the general problem of adding chromatic val...
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ISBN:
(纸本)9781581135213
We introduce a general technique for "colorizing" greyscale images by transferring color between a source, color image and a destination, greyscale image. Although the general problem of adding chromatic values to a greyscale image has no exact, objective solution, the current approach attempts to provide a method to help minimize the amount of human labor required for this task. Rather than choosing RGB colors from a palette to color individual components, we transfer the entire color "mood" of the source to the target image by matching luminance and texture information between the images. We choose to transfer only chromatic information and retain the original luminance values of the target image. Further, the procedure is enhanced by allowing the user to match areas of the two images with rectangular swatches. We show that this simple technique can be successfully applied to a variety of images and video, provided that texture and luminance are sufficiently distinct. The images generated demonstrate the potential and utility of our technique in a diverse set of application domains.
We propose the use of textured splats as the basic display primitives for an open surface fire model. The high-detail textures help to achieve a smooth boundary of the fire and gain the small-scale turbulence appearan...
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We propose the use of textured splats as the basic display primitives for an open surface fire model. The high-detail textures help to achieve a smooth boundary of the fire and gain the small-scale turbulence appearance. We utilize the Lattice Boltzmann Model (LBM) to simulate physically-based equations describing the fire evolution and its interaction with the environment (e.g., obstacles, wind and temperature). The property of fuel and non-burning objects are defined on the lattice of the computation domain. A temperature field is also incorporated to model the generation of smoke from the fire due to incomplete combustion. The linear and local characteristics of the LBM enable us to accelerate the computation with graphics hardware to reach real-time simulation speed, while the texture splat primitives enable interactive rendering frame rates.
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