Contour Filter vs ISO Volume filter

I was wondering why the surface of the contour filter is so much smoother that that of the iso volume filter? Can the same algorithm that is used to generate the surface area of the contour filter be used to generate the surface of the iso volume filter? This way the iso volume filter surface would look better and be more uniform. We could also match the contour and iso volume filter more constantly. I have attached an image that compares the iso volume filter with the contour filer for your reference. The contour filter is on the right and the Iso volume filter is being used on the left. This was constructed using disk_out_ref.ex2

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The output of the Contour filter is not any more smooth than Iso Volume. It just looks that way because the Contour filter is generating surface normals that provide smoother shading during rendering.

If you add the Extract Surface and then Generate Surface Normals filters to the output of Iso Volume, you will see that the added normals make the result look the same as Contour. Likewise, if you change the representation of both to Surface With Edges, you will notice that the two filters provide surfaces with the same facets (except that Contour triangulates its surface).


Thanks Ken. You nailed it, I wonder why I didn’t think of normals. The question actually came out of one of my classes, my trusty cohort Phil write it up.