Smooth surface with sharp edges

[ASims]

Hi,

It has been a while since I visited this forum and it is good to see the activity increased, and some good tips.

I have a number of MRI data sets that I have segmented into skin,fat, muscle and bone labels. The volume was cropped to a region of interest. The labels, eg say skin and bone extend to the limit of the volume.

A closed surface was then generated using the SURFGEN module. Additional material option was checked to create Exterior2 on the boundary. Sharp edges were formed at the limit of the volume

The surface was simplified to reduce the triangle count and then smoothed.

Upon smoothing, the sharp edges that were formed at the limit of the volume were rounded to some extent.

I would like to maintain sharp edges at the limit of the volume.

Is there any way to prevent this rounding of sharp edges in the SmoothSurface module?

Thanks for any comments you can provide.

Regards
Andrew Sims
Graduate School of Biomedical Engineering
University of New South Wales

[ShawnZhang]

An answer from VSG Hotline,

Please try to apply the Edge-Preserving-Smooting filter on the labels before applying surfaceGen.

In contrast with the Gaussian filter, this filter does not smear out the edges because the diffusion is reduced or stopped in the vicinity of edges. Thus, edges are preserved.

[ASims]

Shawn, Thanks for the reply. Firstly apologies for taking so long to reply, I have had to work on other things for quite an extended time and am just getting back to AVIZO again now.

I did not have success with the edge preserving filter as you suggested (applying it to the labels prior to surface gen). It significantly altered my label field whatever values I tried.

What I originally had in mind was something like a feature angle threshold from facet to facet beyond which the edge would be considered sharp and not smoothed.

Another possible option is to perform the surface smoothing in the surface editor on selected triangles only, that way sharp edges should be maintained.

Regards
Andrew Sims
UNSW

[forum_admin]

Hi,

Check out the new RemeshSurface module with Avizo6.2. It worked really well on a number of problematic surfaces that I have before.

-Shawn

[ASims]

Thanks for the suggestion Shawn.

I am currently waiting to see if our installation can get v6.2.

Will update when this happens.

Regards
Andrew Sims
UNSW

[ASims]

Shawn

Sorry this took a while to update, but it took a little while to get 6.2 on our installation. So now that we do, I have been able to try out the Remesh Surface module and it does pretty much exactly what I want. It is a great improvement in surface mesh quality and smoothness and handling of non manifold topology.

Thanks for the tip.

Regards


Andrew Sims
UNSW