Three recent studies have offered an unprecedented view of the human body. The Visible Human Project, the Visible Korean Human (VKH), and the Chinese Visible Human have featured the serial sectioning of whole cadavers, producing cross-sectional images that methodically catalogue gross human anatomy. By volumetric reconstruction, these cross-sectional images can be transformed into three-dimensional (3D) images of anatomic structures. Compiling these 3D images would create an invaluable library for medical education and research. The goal of this report is to promote the expansion of such a library of 3D anatomic images and to help users fully understand and utilize the serially sectioned images. To do this, we will discuss the fundamental techniques and equipment used in the VKH and its preliminary experiments. We will also address new applications of the VKH, including virtual brain surgery, virtual endoscopy, and virtual cardiopulmonary resuscitation via the development of virtual dissection software. Clin. Anat. 19:216-224, 2006. V V C 2006 Wiley-Liss, Inc.

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For realistic virtual dissection, the sectioned images of a cadaver are a desirable material because of their high resolution and real body color. After a volume model is made of the sectioned images, it can be piled or peeled at the intended thickness as if a structure's surface is expanded and shrunken. The purpose of our study was to confirm whether laparoscopic and endoscopic exploration of the processed volume model plays a part in anatomy investigation. The ascending colon was outlined in serially sectioned images and accumulated to build a volume model. While the volume model was being piled or peeled, the ascending colon was observed laparoscopically and endoscopically in comparison with the original sectioned image. The trial efficiently demonstrated layers of the colon wall and surrounding tissues which could not be visualized by conventional macroscopic or microscopic techniques. The availability and contribution of this new method will be confirmed by application to other various organs.

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SUMMARYIn terrain visualization, the quadtree is the most frequently used data structure for progressive mesh generation. The quadtree provides an efficient level of detail selection and view frustum culling. However, most applications using quadtrees are performed on the CPU, because the pointer and recursive operation in hierarchical data structure cannot be manipulated in a programmable rendering pipeline. We present a quadtreebased terrain rendering method for GPU (Graphics Processing Unit) execution that uses vertex splitting and triangle splitting. Vertex splitting supports a level of detail selection, and triangle splitting is used for crack removal. This method offers higher performance than previous CPU-based quadtree methods, without loss of image quality. We can then use the CPU for other computations while rendering the terrain using only the GPU.

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SUMMARYMassive digital elevation models require a large number of geometric primitives that exceed the throughput of the existing graphics hardware. For the interactive visualization of these datasets, several adaptive reconstruction methods that reduce the number of primitives have been introduced over the decades. Quadtree triangulation, based on subdivision of the terrain into rectangular patches at different resolutions, is the most frequently used terrain reconstruction method. This usually accomplishes the triangulation using LOD (level-of-detail) selection and crack removal based on geometric errors. In this paper, we present bimodal vertex splitting, which performs LOD selection and crack removal concurrently on a GPU. The first mode splits each vertex for LOD selection and the second splits each vertex for crack removal. By performing these two operations concurrently on a GPU, we can efficiently accelerate the rendering speed by reducing the computation time and amount of transmission data in comparison with existing quadtree-based rendering methods.

Unlike volume models, surface models, which are empty three-dimensional images, have a small file size, so they can be displayed, rotated, and modified in real time. Thus, surface models of male urogenital organs can be effectively applied to an interactive computer simulation and contribute to the clinical practice of urologists. To create high-quality surface models, the urogenital organs and other neighboring structures were outlined in 464 sectioned images of the Visible Korean male using Adobe Photoshop; the outlines were interpolated on Discreet Combustion; then an almost automatic volume reconstruction followed by surface reconstruction was performed on 3D-DOCTOR. The surface models were refined and assembled in their proper positions on Maya, and a surface model was coated with actual surface texture acquired from the volume model of the structure on specially programmed software. In total, 95 surface models were prepared, particularly complete models of the urinary and genital tracts. These surface models will be distributed to encourage other investigators to develop various kinds of medical training simulations. Increasingly automated surface reconstruction technology using commercial software will enable other researchers to produce their own surface models more effectively.