Another approach is to generate a distance map, threshold at some selected distance, and then re-run marching cubes to generate an expanded surface. I don't really know whether this will help w/ your specific irregular shapes, but we've used it on jagged tumor segmentations and it works pretty well. <br>
<br>for an example implementation, see updatedistancemapvolume and updatemodelpipeline in [1]<br><br>that code uses a vtk->itk wrapper [2] around an itk dmap function, but the extra layer is convoluted. I think there is a distance map function available directly in vtk for use instead.<br>
<br>-Isaiah<br><br>[1] <a href="https://github.com/ihnorton/Slicer-DistanceTransformModel/blob/master/Logic/vtkSlicerDistanceTransformModelLogic.cxx">https://github.com/ihnorton/Slicer-DistanceTransformModel/blob/master/Logic/vtkSlicerDistanceTransformModelLogic.cxx</a><br>
[2]
<a href="http://viewvc.slicer.org/viewvc.cgi/Slicer4/trunk/Libs/vtkITK/vtkITKDistanceTransform.cxx?revision=17572&view=markup">http://viewvc.slicer.org/viewvc.cgi/Slicer4/trunk/Libs/vtkITK/vtkITKDistanceTransform.cxx?revision=17572&view=markup</a><br>
<br><div class="gmail_quote">On Fri, Sep 2, 2011 at 11:26 AM, Jothy <span dir="ltr"><<a href="mailto:jothybasu@gmail.com" target="_blank">jothybasu@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Has anyone have any idea about how to do this?<br><br>Thanks<br><font color="#888888"><br>Jothy</font><div><div></div><div><br><br><div class="gmail_quote">On Thu, Sep 1, 2011 at 9:41 AM, Jothy <span dir="ltr"><<a href="mailto:jothybasu@gmail.com" target="_blank">jothybasu@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi all,<br><br>I am trying to expand surfaces(isotropically/anisotropically) generated from vtkDiscreteMarchingCubes. I used this as reference <a href="http://www.mlahanas.de/CompGeom/Margins.htm" target="_blank">http://www.mlahanas.de/CompGeom/Margins.htm</a>.<br>
<br>It works well for more or less regular volumes. But for irregualr structures it doesn't work properly. For example, spinal cord (looks in "C" shape in sagittal view) it doesn't expand in the anterior direction. I even tweaked the sigma in vtkThinPlateSplineTransform.<br>
<br>Any hints?<br><br>Thanks<br><font color="#888888"><br>Jothy<br></font></div>
</blockquote></div><br></div></div></div>
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