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

[Dongqing Chen]

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,
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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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