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      • HARVEST
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      Surface reconstruction using variational interpolation

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      final_thesis_etd_nov23.pdf (1.633Mb)
      Date
      2005-10-07
      Author
      Joseph Lawrence, Maryruth Pradeepa
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      Surface reconstruction of anatomical structures is an integral part of medical modeling. Contour information is extracted from serial cross-sections of tissue data and is stored as "slice" files. Although there are several reasonably efficient triangulation algorithms that reconstruct surfaces from slice data, the models generated from them have a jagged or faceted appearance due to the large inter-slice distance created by the sectioning process. Moreover, inconsistencies in user input aggravate the problem. So, we created a method that reduces inter-slice distance, as well as ignores the inconsistencies in the user input. Our method called the piecewise weighted implicit functions, is based on the approach of weighting smaller implicit functions. It takes only a few slices at a time to construct the implicit function. This method is based on a technique called variational interpolation. Other approaches based on variational interpolation have the disadvantage of becoming unstable when the model is quite large with more than a few thousand constraint points. Furthermore, tracing the intermediate contours becomes expensive for large models. Even though some fast fitting methods handle such instability problems, there is no apparent improvement in contour tracing time, because, the value of each data point on the contour boundary is evaluated using a single large implicit function that essentially uses all constraint points. Our method handles both these problems using a sliding window approach. As our method uses only a local domain to construct each implicit function, it achieves a considerable run-time saving over the other methods. The resulting software produces interpolated models from large data sets in a few minutes on an ordinary desktop computer.
      Degree
      Master of Science (M.Sc.)
      Department
      Computer Science
      Program
      Computer Science
      Supervisor
      Neufeld, Eric
      Committee
      Mould, David; Horsch, Michael C.; Gander, Robert
      Copyright Date
      October 2005
      URI
      http://hdl.handle.net/10388/etd-11232005-163941
      Subject
      implicit functions
      inter-slice distance
      surface reconstruction
      contours
      variational interpolation
      triangulation
      radial basis functions
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