[vtkusers] Missing volume regions (holes) in output of vtkDiscreteMarchingCubes

[Bryn Lloyd]

Hi

 

Applying vtkDiscreteMarchingCubes to a label field (segmented 3d volume), I
get some unwanted holes in the output.

 

What I mean by hole is the missing volume regions, which occur at
multi-label junctions/interfaces. These volumes are outside of all closed
surfaces, which are computed for each label value.

An example is shown in the image
http://www.vision.ee.ethz.ch/~blloyd/ScreenShot_BadSurfaceExtraction.png. I
extracted all triangles, which are not duplicate. This should be the set of
triangles on the outer surface. However, clearly in the output of
vtkDiscreteMarchingCubes contains internal outer surface triangles, i.e. the
surface of holes.

 

In 2D this would happen if I had a square with three labels. Then an
internal triangle would actually be external to each label/material region.

 

x---------x

|               |

|---------|

|   \     /   |

x----x----x

 

Is there any way I can avoid these holes, using classes in VTK? One way I
can think of, is to extract the surface of the voxels for each material
label. This would, however, result in much stronger staircasing.

Any ideas?

 

Thanks

Bryn

 

 

 

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