| Author | Message | ||
     Lars Ahnland Rating: N/A |
Well? | ||
| Dave Comeau Rating: N/A |
The i-o display i-glasses that I have (old version, not VGA) have two LCD monitors, one for each eye. So the frame rate is not split, each LCD gets one stream. So no flicker. Very nice (except the tradeoff is the resolution and color is not so great.) | ||
| Lars Ahnland Rating: N/A |
Is it the flicker that spilts the framrate with shutterglasses? | ||
| Anonymous Rating: N/A |
It's the fact that you have to display two seperate images on one screen. So your refresh rate is essentially cut in half. Thats why if you up your refresh rate the flicker goes away. "Is it the flicker that spilts the framrate with shutterglasses? " No...its not the flicker that splits the framerate. Its the split framerate that causes the flicker. | ||
| Lars Ahnland Rating: N/A |
Aha. Thx for the info. | ||
| Anonymous Rating: N/A |
Different models of stereoscopic HMDs use different methods -- the key is that you have to deliver two separate video streams, one for each eye -- how that's done varies. Some higher-end HMDs (Virtual Research) had two separate video inputs (both at full refresh rate, of course) -- so that meant two separate video sources and two cables. To do the same over one video card and one cable, something's got to give -- both streams have to be squeezed into one. So something gets cut in half for each stream of images: either your resolution or your frame rate. The old Forte VFX1 used interleaved stereo: every odd scan line went to one eye, even line to the other... cutting your vertical resolution per image in half. Most recent HMDs instead use alternating frames (like shutter glasses), so one entire image is sent for the left, then one for the right. Obviously this page flipping cuts your refresh rate in half... but unlike shutter glasses, you don't see any flicker in HMDs. That's because LCDs retain their state; their frames' brightness doesn't fade like the phosphors in a CRT, requiring a refresh. | ||
| Lars Ahnland Rating: N/A |
Interesting. | ||
| Lars Ahnland Rating: N/A |
This means that the framerate will be split in half using HMD´s as well as shutterglasses? | ||
| Alatar Rating: N/A |
The point is that to show proper 3D you need double the bandwidth of the same thing in 2D. So unless the entire system has two data paths all the way through, there is always some bit that has to create two images out of one. As a result, each eye is only going to see only half the data that a normal 2D stream would present -- although there are ways of alleviating this using frame doubling etc. The only good way to do it is to have two image streams all the way through the system. Alatar | ||
| Alatar Rating: N/A |
To actually answer your question, one of four things is going to happen: 1. Your system maintains two separate video streams all the way through the output pathway (you see frame 1 - 2 - 3 - 4 - 5 ....) 2. Each second frame is lost, resulting in bad flicker (you see frame 1 - blank - 3 - blank - 5 ...) 3. Each second frame is lost, but is doubled, resulting in less flicker, but is still jerky (you see 1 - 1 - 3 - 3 - 5...) 4. You see all the frames but they are otherwise degraded by line interlacing or similar technique (you see 1 - 2 - 3 - 4 - 5 but in low quality) You would have to figure out which of these alternatives applies to your particular equipment. Alatar | ||
| Anonymous Rating: N/A |
You can turn up the refresh rate, which helps. Sony LDI-D100B has a max refresh of 85 Hz... so that'd be 42.5 frames/sec per eye, which isn't bad. Who has a newer stereoscopic HMD and can list what its max rate is? | ||
| Anonymous Rating: N/A |
P.S. - Turning up your refresh rate with shutter glasses can increase the amount of ghosting you see. (The phosphors are still glowing from the previous eye's image while the current one is being displayed.) So you have to trade-off flicker vs. ghosting. This is one area where HMDs have shutter glasses beat, in my opinion. | ||
| Lars Ahnland Rating: N/A |
I got a problem in Lineage 2 beta, with framerate being sverely hit when turning on my shutterglasses. I don´t know if this has anything to do with the pageflippning, bandwidth or the actual stereovision hitting cpu. I don´t have any problems with framerates in UT2003 or CS. | ||
| BOPrey Rating: N/A |
Let me just inject something here. When a gamers talks about frame rate, he's talking about how frequent a scene is updated. Yes, frame rate gets cut in half whenever to turn on stereo regardless whether you use shutter glasses or HMD. The reason is the video card has to render the scene TWO times. One for the left eye, one for the right eye. Lars, Some game do set their own reflesh rate. Check it config file or option. I also think nvidia has an option in the video setting that lets you to override the reflesh rate set by the application. | ||
| Christoph Bungert (Admin) Rating: N/A |
Well, no. The loss in frame rate when activating a stereo driver varies from game to game, scene to scene, stereo driver to stereo driver, VGA driver to VGA driver, OS to OS, CPU to CPU, GPU to GPU, etc. A typical figure is 20-30 percent, but the frame rate never cuts exactly into half. The rendering process in general and in the stereo-case is much more complex. The driver doesn't exactly calculate everything twice. There are optimizations. Christoph |
