[vtkusers] volume calculation

[Murat Aydın]

  ----- Original Message ----- 
  From: Karthik Krishnan 
  To: Murat Aydın 
  Cc: vtkusers at vtk.org 
  Sent: Wednesday, September 09, 2009 11:22 AM
  Subject: Re: [vtkusers] volume calculation


  2009/9/9 Murat Aydın <murat.aydin at netcad.com.tr>

    Hi,

    I am calculating volume of solid constructed by vtkDelaunay3D applied to a point cloud.

    i am using vtkGeometryFilter -> vtkTriangleFilter -> vtkMassProperties in order to get volume of the solid.

   
    I am not sure whether the calculated volume is correct,

  No issues AFAIK.
   

    because if i add
    vtkDecimatePro filter or vtkSmoothPolyDataFilter the volume changes.

  It is certainly going to change a bit. The locations of the points comprising the polydata are going to change due to smoothing and this is going to impact the projected volume.
   
    Without vtkDecimatePro , the volume seems to be more than it should be.What should i do to find true volume? Thanks in advance.

  How do you arrive at that conclusion. Please take a look at the paper referenced in the header.

  I am comparing my results with a software called Surpac. I am assuming Surpac is correct because it is a well known software in mining industry.

  At most there may be numerical issues with computing the projected volume of axis aligned triangles. The filter alleviates this by computing the volume along the three axes and averaging them. 




  -- 
  karthik

  I am sure vtkMassProperties is working correctly. My problem is that i am not sure whether vtkDelaunay3D represents my solid correctly. If so, volume will be correct. How can i make vtkDelaunay3D  to represent my solid correctly? How can i remove unneccessary triangles? Or should i use vtkLinearSubdivisionFilter to increase number of triangles? I am new to vtk, so please give me some advise.
  In some cases i have less number of points in point cloud, and in some cases i have many points in point cloud.
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