[vtkusers] can I use normals to evaluate the gradients?

[Dongqing Chen]

gradient vectors of iso-surface at each point, if I use vtk to generate iso-surface into 3D triangle mesh surface.

Best Wishes,
-----------------------------------------------------------------
Dongqing Chen
Ph.D Research Assistant
Rm. 07, Paul C. Lutz Hall
Computer Vision & Image Processing (CVIP) Lab
Department of Electrical & Computer Engineering
Speed School of Engineering
University of Louisville
Louisville, KY. 40292
U.S.A
Email: dqchen at cvip.louisville.edu
Phone:+1-502-852-2789 (Lab)
            +1-502-852-6130 (Office)
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  ----- Original Message ----- 
  From: Dongqing Chen 
  To: vtkusers at vtk.org 
  Sent: Saturday, July 15, 2006 2:02 PM
  Subject: [vtkusers] can I use normals to evaluate the gradients?


  Dear All:

     I am trying to get the gradient vectors of all the vertices of triangle surface mesh. One of my friend gave me some advice list as below:

  *************************************************************************************************
  Triangle meshes are piece-wise linear approximation of smooth manifold.
  the so-called gradient is not well-defined. you can use any reasonable
  approximation from the gradient (normal) of the incident faces.
  **************************************************************************************************

    Can I just simply use to vtkPolydataNormals to get all the normal vectors? Then how can I relate the normal vectors with the gradient vectors at the points?

  Best Wishes,
  -----------------------------------------------------------------
  Dongqing Chen
  Ph.D Research Assistant
  Rm. 07, Paul C. Lutz Hall
  Computer Vision & Image Processing (CVIP) Lab
  Department of Electrical & Computer Engineering
  Speed School of Engineering
  University of Louisville
  Louisville, KY. 40292
  U.S.A
  Email: dqchen at cvip.louisville.edu
  Phone:+1-502-852-2789 (Lab)
              +1-502-852-6130 (Office)
  -----------------------------------------------------------------


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