[vtk-developers] merge request for vtkCamera.cxx eyeseparation and near far planes correction (UNCLASSIFIED)

Aashish Chaudhary aashish.chaudhary at kitware.com
Thu Mar 17 23:41:39 EDT 2016


Hi David C.,

We wrote an source article some time back on it:
https://blog.kitware.com/paraview-in-immersive-environments. Also worth
looking at this another article:
https://blog.kitware.com/immersive-paraview-experiences-at-idaho-national-laboratory
for some of the motivation and concepts behind the work.

Since there is no concept of units in VTK, all of the numbers are dependent
on user picking a unit and if they all are in meters or centimeters or
anything else, it should work as expected. Typically a VR system has a
reference point using which distance are measured. Some systems report
inches but most of the modern ones report meters or centimeters. An
separation of 6 cm (or 0.06 m) is chosen for that reason but it is not
mandatory. As far as the documentation goes, there is really one method
which is important in vtkCamera and it has a reference for the paper in
there (please see below). We kept the same variable names so referring the
paper should be straightforward. If you have any particular suggestion on
how to improve the documentation please let us know (A patch is also
welcome).

- Thanks,


//----------------------------------------------------------------------------

void vtkCamera::ComputeOffAxisProjectionFrustum()

{

  this->ComputeWorldToScreenMatrix();


  // \NOTE: Varibles names reflect naming convention used in

  // "High Resolution Virtual Reality", in Proc.

  // SIGGRAPH '92, Computer Graphics, pages 195-202, 1992.


  // OffAxis calculations.




On Thu, Mar 17, 2016 at 7:28 PM, David Gobbi <david.gobbi at gmail.com> wrote:

> On Thu, Mar 17, 2016 at 5:07 PM, David Cole <DLRdave at aol.com> wrote:
>>
>>
>> Thank you for the tidbit of information about EyeSeparation. So with a
>> value of 0.06, is it 6% of the x-axis (width) of the screen then?
>>
>
> I don't know how it is implemented in VTK.  All I was saying is that it
> cannot
> be in real-world meters, because vtkCamera doesn't know the size of the
> display and therefore cannot convert distances in the observer's world to
> distances in the virtual-world.
>
>  - David
>



-- 



*| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
*| http://www.kitware.com/company/team/chaudhary.html
<http://www.kitware.com/company/team/chaudhary.html>*
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