[vtkusers] Mean curvature

[Prathap Nair]

Hi,

Thanks Philip for the temporary class vtkCurvatureTensor, I am currently trying to use that instead of the old class. I am also trying to study your updated vtkCurvatures code that calculates Principal Curvatures. I tried using the suggestion given to me by Joseph but it yielded the same result, unfortunately.

One observation i made was that, the results i mentioned was what i got using VTK ver 4.2, i.e, zero value for mean curvature at all points and for gaussian curvature they ranged from +5 to +50. On trying VTK 4.4 without changing any code i got values ranging between -1 to +1 for both mean and gaussian curvatures. I find that rather strange.

I am not really well versed with the mathematics and geometry related with curvatures since i am just trying to implement an algorithm. But I thought i ought to let this fact be known to all. As far as the data I am using is concerned, its a very well defined facial scan in wavefront obj format with 59207 vertices and 117374 triangular faces.

As pointed out by Philip, the bug mentioned by Gorman and Mathieu shouldnt affect the mean calculation in the case of the old vtkCurvatures class as vtkExtractTensorComponents isn't called at all.

Anyhow I hope one of Philip's updated classes works for my task, and I am eagerly waiting for the final updated absract curvature class for my future work.

Cheers,

Prathap Nair
Dept of Electronic Engineering,
Queen Mary, University of London,
Mile End Road, London E1 4NS (UK).
  ----- Original Message ----- 
  From: José Nsasi B. 
  To: vtkusers at vtk.org 
  Sent: Wednesday, July 06, 2005 3:24 PM
  Subject: [vtkusers] Re: Mean curvature


  Hi;

  The mean curvature works very well and its estimation looks better than gauss curvature.

  Try to use:

   this->curvm->SetCurvatureType(1);//this->curvm->SetCurvatureTypeToMean();

  mvals=this->curvm->GetOutput()->GetPointData()->GetScalars();

  Best Regards





  -------------------------------------------------------------- 
  Joseph Nsasi Bakambu, 


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