[vtkusers] Best 3D rendering technique for a point cloud?

[David Gobbi]

Hi Jason,

If the 3D Delaunay triangulation works on your dataset, then you are
already halfway to a solution.  The next step is to use vtkProbeFilter
to resample the data onto a regular 3D grid.  Then you can do volume
rendering.  The sequence should be as follows:

1) If your point cloud is solid then vtkDelaunay3D should be able to
produce a vtkUnstructuredGrid from it that is made from tetrahedrons

2) Set the output of Delaunay3D as the input of vtkProbeFilter.  Use
probe->SetSourceConnection() to specify a vtkImageData grid that is a
reasonable size and spacing for doing the volume rendering.  If you
look around, you should be able to find good examples of how to do
this.

3) Cast the output of vtkProbeFilter to UnsignedChar or UnsignedShort
(if it isn't already) and then do a volume rendering of it.

There are also some VTK volume renders that can render a
vtkUnstructuredGrid directly, but for performance reasons you are much
better off to convert your data into a vtkImageData before rendering
it.  Note that I have never tried what I am suggesting in this email,
but I have confidence that it will work.

   David


On Thu, Jul 22, 2010 at 3:14 PM, Jason T. <jasontang65 at gmail.com> wrote:
>
> Hello,
>
> I currently have a large, evenly spaced point cloud that is color mapped
> with scalar data. It looks pretty good in 2D and 3D but once you zoom in the
> resolution deteriorates dramatically because of the pixel spacing (which
> cannot vary because the pixel data comes from a file).
>
> I just want to hear some of your opinions on the best way to create a 3D
> rendering using this data to fit nicely on a 3D surface (right now the point
> cloud is a vtkPolyData).
>
> I've tried vtkImageData and GDCM modules (both of which don't work very well
> in my case to my dismay) and delaunay triangulation (which looks good but
> it's hollow which is a problem since the point cloud is "solid").
>
> Thanks everyone,
> Jason
> --
> View this message in context: http://vtk.1045678.n5.nabble.com/Best-3D-rendering-technique-for-a-point-cloud-tp1842848p1842848.html
> Sent from the VTK - Users mailing list archive at Nabble.com.
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