[vtkusers] Re:stereo rendering with volumepro1000, not working properly?
Dr. Daniel James White PhD
dan at chalkie.org.uk
Wed Mar 10 04:44:29 EST 2004
Hi Lisa,
thanks for your reply!
> If your ray cast mapper is not correctly working in stereo, then the
> VolumePro mapper won't either - you are still using a version of VTK
> with the "bug" in it. I know we fixed it on a branch - I'll have to
> check tomorrow whether it is fixed on the main tree or not. The
> problem was (maybe is) that the left/right flag was switched right
> after setting up the camera for that eye - which means that by the
> time these volume mappers asked for the current matrix the wrong one
> was returned.
My VTK is a recent CVS build, and it looks like the bug was not fixed
in that. It was built after Xmas.
How can I check my present code for the bug fix?
>
>
> So - if you had the fix the ray cast mapper would work, but I am still
> not sure about the VolumePro mapper. I believe that we set up the
> matrix is VLI by using just the position / focal point from the camera
> (which I do not believe are altered at all in stereo mode). The
> disparity you are seeing is because the matrix for OpenGL changes
> between eyes, and the texture mapped polygons (with the results from
> the board) are rendered in two different places because of this. The
> images themselves will be identical.
So do you mean that the 2 images from the volpro1000 board are the
same, and not really left and right eye images, but are just placed in
different places....? Do you mean this happens with the
intermixintersectinggeometryon flag causes this?
Surely the volumepro1000 board should be able to make 2 images , one
from each eye, and send them to VTK in both perceptive and parallel
modes, then it should just work right?
>
> I have to look at the code in vtkCamera to see what is done in
> parallel for stereo rendering - I am not sure this is intended to work
> at all (it does not really make sense, right?) And the VolumePro
> mapper only works in parallel......
Yes, I guess parallel stereo doesn't make physical or theoretical
sense, BUT, at least using my setup and my eyes, the parallel image
using isosurfaces "looks" good, and there is a good impression of
depth...... so I suppose it might "work" for ray casting methods also.
The thing is, at present only the parallel mode is able to zoom in and
out using volumepro1000. The perspective mode using volumepro1000 does
work, but not zooming, only spinning around.
So it would be nice to use pseudo-nonsense-but-still-looks-ok stereo in
parallel mode with the volumepro1000 mapper....
I hope the VTK bug fix corrects this....?
If I can show people stereo3D real time zooming and spinning of their
confocal microscope data, volume rendered using the volumepro1000
board, they and my boss will be very happy!
cheers
Dan
>
> Lisa
>
>
> At 11:47 AM 3/9/2004, Dr. Daniel James White PhD wrote:
>> Hey Kristen,
>>
>> I hope you can pass this on to your technical people.
>> VTK stereo people may want to look also.
>>
>> I have questions about using my new volumepro1000 hardware volume
>> rendering / ray casting board to do stereo volume rendering using
>> VTK/openGL quad buffered (page flipping) stereo with crystal eyes
>> glasses, on my red hat linux machine, with xig.com accelerated X
>> server (for quad buffered stereo using the ATI Radeon 8500 graphics
>> card and crystal eyes lcd shutter glasses system)
>>
>> My stereoscopic viewing system works with several 3D/stereo enabled
>> programs, for molecular modeling and other stuff, such as bodil,
>> pymol, VMD......These all use OpenGL stereo rendering with polygons.
>>
>> Also with the VTK program I am using, called MayaVi, stereo has been
>> enabled, and works great for iso surface rendering in both parallel
>> and perspective projection modes.
>>
>> I have noticed that there are problems with the VTK software
>> raycasting code (vtkCompasiteRayCastMapper I think it is called) that
>> seem to make the stereo rendering left right swapped, or at least
>> some how weird for volume rendering. I think is supposed to be
>> getting fixed in VTK...is it?..... anyway
>>
>> So I tried the stereo viewing mode using the VTK volumepro1000mapper,
>> which we are testing (with good results in mono) in MayaVi. There
>> are problems...
>>
>> 1) The left and right eye images are made, but they have no "depth".
>> The volumepro generated image looks "flat" and in the plane of the
>> monitor, whereas an iso surface rendered image jumps out of the
>> screen at you nicely, as it should.
>>
>> 2) (maybe the same problem) In parallel viewing with
>> volumepro1000mapper and isosurface rendering in the same window,
>> opaque iso surface rendered stuff close to the camera looks like it
>> is in front of the volumepro100 rendered image, and opaque iso
>> surface rendered stuff far away to the camera looks like it is
>> behind the volumepro100 rendered image. As the data set is rotated
>> the iso surface rendered stuff appears from behind and then vanishes
>> behind the volume rendered image of the same feature in the data.
>> In perspective viewing the same is true.
>>
>> 3) In parallel projection, If I turn on the inter mix intersecting
>> geometry flag on, then the volumepro1000 left and right eye images
>> jump apart on the screen, and with the shutter glasses on, the image
>> looks like it is just in front of the screen, but still "flat". In
>> perspective projection, the left and right images with mix
>> intersecting geometry on, the left and right images move further
>> apart the more "side on" I view the data set.
>>
>> So I wonder..... the VP1000 board and vli3 library can do a
>> perspective or parallel projection just fine for a single camera
>> position or eye, but when it uses 2, something is going wrong with
>> the camera positions, such that they are not left and right eye, but
>> something else. I know parallel projection should never really work
>> for left/right eye stereo, but the perspective projection should work
>> right?
>>
>> Is this a problem with VTK, or vli3 (the VP1000 driver), or the
>> VP1000board, or what?
>> I see no reason why OpenGL stereo perspective projection
>> volumepro1000 rendering should not work in theory. VTK/vli3 just has
>> to talk to openGL properly to make the left and right images come
>> from the correct camera positions..... right?
>>
>> Am I doing something wrong or missing a point?
>>
>> Why does the intermixintersectinggeometry flag have this effect?
>>
>> Any ideas?
>> cheers
>>
>> Dan
>>
>>
>> Dr. Daniel James White BSc. (Hons.) PhD
>> Cell Biology
>> Department of biological and environmental science
>> PO Box 35
>> University of Jyväskylä
>> Jyväskylä FIN 40014
>> Finland
>> +358 (0)14 260 4183 (work)
>> +358 (0)414740463 (mob)
>>
>> http://www.chalkie.org.uk
>> dan at chalkie.org.uk
>> white at cc.jyu.fi
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>
>
Dr. Daniel James White BSc. (Hons.) PhD
Cell Biology
Department of biological and environmental science
PO Box 35
University of Jyväskylä
Jyväskylä FIN 40014
Finland
+358 (0)14 260 4183 (work)
+358 (0)414740463 (mob)
http://www.chalkie.org.uk
dan at chalkie.org.uk
white at cc.jyu.fi
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