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-   -   are anaglyphs red/green or red/cyan? (https://forum.worldviz.com/showthread.php?t=1745)

michaelrepucci 12-09-2008 12:01 PM

are anaglyphs red/green or red/cyan?
 
I would like to buy the most appropriate glasses for the job. The documentation says you should use red/green glasses when using viz.ANAGLYPHIC. But if I display a white object, its two images appear as red/cyan to the naked eye, which is another common color scheme for anaglyphs. So which system is Vizard using, and which glasses should I buy?

farshizzo 12-09-2008 12:19 PM

Vizard uses red/cyan for anaglyphic.

michaelrepucci 12-17-2008 07:22 AM

Do you guys have a particular manufacturer, make, and model of red/cyan glasses that you could recommend for use with Vizard? We're having lots of problems reducing ghosting to acceptable levels.

farshizzo 12-17-2008 11:19 AM

I've only ever used the ones they hand out for free at conferences, so I can't make any specific recommendations. The ghosting is an inherent artifact of anaglyphic stereo, so I don't think you'll be able to reduce it much using different glasses.

michaelrepucci 12-17-2008 11:41 AM

Well, that's not really true. The ghosting is related to the filtering properties of the glasses, so those glasses with a better bandpass filter and good cut-offs would be better. We even notice a significant reduction in ghosting simply from doubling up those paper red/green glasses, rather than using just one layer. But it's not enough to completely remove it, and we're having a perceptual problem (Pulfrich effect), with some of our stimuli.

Can you provide more information about how Vizard renders anaglyphic stereo?

farshizzo 12-17-2008 01:00 PM

Vizard uses the glColorMask command to render anaglyphic stereo. Basically, the code works like this:
Code:

glColorMask(GL_TRUE, GL_FALSE, GL_FALSE, GL_TRUE);
RenderLeftEye();

glColorMask(GL_FALSE, GL_TRUE, GL_TRUE, GL_TRUE);
RenderRightEye();

That's pretty much it. If you need more advanced control over the color filtering, then you will have to use a post-process shader. Let me know if you are interested in this and I can provide you some code.

michaelrepucci 12-17-2008 01:30 PM

Oh, an elegantly simple solution indeed.

I'm not sure what I could do with a post-process shader, but if I could change the background color without effecting the color of the anaglyphic objects in the scene, then I could put a very faint reddish-cyanish-brown color in the background which would look perceptually like the red (cyan) ghost image that is showing up through my cyan (red) filter. This would make the ghost perceptually invisible. Unfortunately, when I change the background color, it alters the colors of the anaglyphs, since it too must be put through the color mask. I gather I can't selectively activate certain objects as anaglyphs, or is that what I can do with a shader?


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