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We describe algebraic methods for creating implicit surfaces using linear combinations of radial basis interpolants to form complex models from scattered surface points. Shapes with arbitrary topology are easily represented without the usual interpolation or aliasing errors arising from discrete sampling. These methods were first applied to implicit(More)
DNA microarray provides a powerful basis for analysis of gene expression. Data mining methods such as clustering have been widely applied to microarray data to link genes that show similar expression patterns. However, this approach usually fails to unveil gene-gene interactions in the same cluster. Association rule mining and loglinear models have been(More)
We can supplement the clinical value of an optical colonoscopy procedure if we can continuously co-align corresponding virtual colonoscopy (from preoperative X-ray CT exam) and optical colonoscopy images. In this work, we demonstrate a computer vision algorithm based on optical flow to compute egomotion from live colonoscopy video, which is then used to(More)
Simulation of large-scale neural models results in the generation of significant amounts of time-varying data for analysis and interpretation. While computational expense and resources were a major issue in the past, the availability of powerful desktop workstations has made it possible to handle not only more realistic models of neurons (containing(More)
We present a new ray-tracing algorithm for volume rendering which is designed to work efficiently when the data of interest is distributed sparsely through the volume. A simple preprocessing step identifies the voxels representing features of interest. Frequently this set of voxels, arbitrarily distributed in three dimensional space, is a small fraction of(More)
In this paper, we focus on the robustness and stability of our algorithm to plot the position of an endoscopic camera (during a colonoscopy procedure) on the corresponding pre-operative CT scan of the patient. The colon has few topological landmarks, in contrast to bronchoscopy images, where a number of registration algorithms have taken advantage of(More)
We present a new constraint-based implicit active contour, which shares desirable properties of both parametric and implicit active contours. Like parametric approaches, their representation is compact and can be manipulated interactively. Like other implicit approaches, they can naturally adapt to non-simple topologies.Unlike implicit approaches using(More)
Co-located optical and virtual colonoscopy images provide important clinical information during routine colonoscopy procedures. Tracking algorithms that rely on image features to align virtual and optical images can fail when they encounter blurry image sequences. This is a common occurrence in colonoscopy images, when the endoscope touches a wall or is(More)