[vtkusers] Orthographic projection onto arbitrary plane

[David Gobbi]

Hi Sebastien,

So your goal is to make VTK do an orthographic projection instead of
a perspective projection?  If so then you don't have to build your own
transform, the camera has an orthographic mode that it calls the
"ParallelProjection" mode:

camera = renderer.GetActiveCamera()
camera.ParallelProjectionOn()
camera.SetParallelScale(500.0) # tweak as needed

Set the camera pose in the usual way:

camera.SetFocalPoint(0.0, 0.0, 0.0)
camera.Position(0.0, 0.0, -500.0)
camera.SetViewUp(0.0, 1.0, 0.0)

Hope this helps.

 - David



On Thu, May 31, 2018 at 8:49 AM, smurphy <sebastien.murphy at gmail.com> wrote:

> Hello,
>
> I am (desperately) trying to make an orthographic projection in a plane of
> a
> geometry (see picture attached).
> The only help I can find online is this thread so I am replying to this old
> post.
> I tried to do the following code but without success. It simply place the
> camera in the correct position but does not actually make the
> transformation. Am I missing a line, should I pass the transform to the
> camera in a certain way?
> Thanks a lot,
> Sebastien
>
> #center of the geometry volume is 0,0, -500
> FocalPoint=[0,0,-500]
> Position=[0,0,-500]
> ViewUp=[0,0,-500]
> Transform=vtk.vtkPerspectiveTransform()
> Transform.SetupCamera(Position, FocalPoint, ViewUp)
> Transform.Ortho(-1000,1000,-1500,1500,-500,500)
> <http://vtk.1045678.n5.nabble.com/file/t342442/Screen_Shot_
> 2018-05-31_at_16.png>
>
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