[vtkusers] Distortions in Volumerendering in VR-Mode (HTC Vive)

[Sebastian Heerwald]

Hey,


Thank you for your reply.

I have build a little program which only loads a volume dataset and displays it within the RenderWindow.

Since the OpenVR interface is a little bit hackish within VTK the only thing that decides whether it renders for OpenVR or for normal 2D-Display is whether we link against vtkOpenVR and vtkRenderingOpenVR modules or not.

Everything code related is the same.


So to reply to your Question:

> Could you try rendering a volume with an identity matrix set as its transformation?


I've build this simple program and it only places a volume dataset within the world without any transformation. The volume is directly given to the GPUVolumeRCMapper without any transformation. In "2D"-Renderwindow everything is fine. Also in anaglyph rendering I get a nice 3D View.

But when I link against OpenVR module the view dependend distortions appear within VR. I've tried some things.

All I can say is, that the errors appear if I look at any edge or corner of the surrounding (invisible) boundingbox around the rendered volume. If I look directly on one side of the boundingbox everything seems fine.


The only thing I can imagine from this perspective is, that the GPUVolumeRCMapper gets wrong view directions for the eyes. But the vtkOpenVRCamera objects seems to do everything right.


I don't know how to adjust the clipping box / bounding box you mentioned. Can you explain how I can do this, maybe this helps me to debug further?


Sincerely,

Sebastian

________________________________
Von: vtkusers <vtkusers-bounces at vtk.org> im Auftrag von Alvaro Sanchez <alvaro.sanchez at kitware.com>
Gesendet: Mittwoch, 7. Dezember 2016 18:14
An: polybos
Cc: VTK Users
Betreff: Re: [vtkusers] Distortions in Volumerendering in VR-Mode (HTC Vive)

Hi,

I have never tested the GPUVolumeRCMapper with OpenVR but as far as I remember Ken mentioned some time ago that he encountered a clipping/bbox related issue when adjusting the volume's orientation and position. Could you try rendering a volume with an identity matrix set as its transformation?,  this might give you a hint of what the mapper is doing wrong.

Cheers,
Alvaro

On Wed, Dec 7, 2016 at 11:38 AM, polybos <franz at znarfsoft.de<mailto:franz at znarfsoft.de>> wrote:
Sebastian Heerwald wrote
> If I look onto the volume rendering and move around it, there appear
> "refraction" lines.

Unfortunately I cannot help with this issue but I would also be very pleased
if someone could help here. Or did you, Sebastian, already achieve some more
insights into this problem?
I also get such distortions on the HTC Vive when using
vtkVolumeRayCastMapper, while everything seems perfectly well in a mesh-only
rendering.

Does anyone have similar issues? Maybe with Occulus Rift? As far as I
understand Sebastian just test with a HTC Vive. At least I can only test
with a HTC Vive.



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Alvaro Sanchez
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