[vtkusers] Margin around surfaces

[Isaiah Norton]

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.

for an example implementation, see updatedistancemapvolume and
updatemodelpipeline in [1]

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.

-Isaiah

[1]
https://github.com/ihnorton/Slicer-DistanceTransformModel/blob/master/Logic/vtkSlicerDistanceTransformModelLogic.cxx
[2]
http://viewvc.slicer.org/viewvc.cgi/Slicer4/trunk/Libs/vtkITK/vtkITKDistanceTransform.cxx?revision=17572&view=markup

On Fri, Sep 2, 2011 at 11:26 AM, Jothy <jothybasu at gmail.com> wrote:

> Has anyone have any idea about how to do this?
>
> Thanks
>
> Jothy
>
>
> On Thu, Sep 1, 2011 at 9:41 AM, Jothy <jothybasu at gmail.com> wrote:
>
>> Hi all,
>>
>> I am trying to expand surfaces(isotropically/anisotropically) generated
>> from vtkDiscreteMarchingCubes. I used this as reference
>> http://www.mlahanas.de/CompGeom/Margins.htm.
>>
>> 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.
>>
>> Any hints?
>>
>> Thanks
>>
>> Jothy
>>
>
>
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