Tearing and v-sync

[lionfish]

I've noticed that the video in the 3d environment has severe tearing (this is caused by the graphics driver drawing images to the LCD that have not yet finished rendering).
The obvious solution is to enable vsync, which I tried with various combinations of the viz.vsync(viz.ON) command, settings in the nvidia control panel and with a utility called RivaTuner. The result was that the tearing just appeared near the top of the screen, and the video occasionally 'jerked' or 'jittered' - as if several refreshes are skipped.

This is being run on an ASUS Dell 64-bit laptop, running windows 7. The graphics card is an nVIDIA GeForce GTX 260M. I've checked the graphics drivers are up to date, and have just upgraded vizard to the latest version (v3.15).

I've also tried forcing triple buffering using RivaTuner, and have tried tweaking a lot of random options.

I was wondering if there's a way in vizard to reduce the frame rate, without v-sync it's nearly at 200fps. I was thinking if I could reduce that to 50fps, then the tearing might stop. (and won't have added 'jittering' either)

Thanks for any ideas,

Mike Smith
University of Edinburgh.

[Jeff]

You should leave vsync on, which it is by default in Vizard. With it on what is the framerate you are getting? You can check that by hitting F4 and it should be staying close to 60 unless unless the scene is more complex.

[lionfish]

Thanks for the response.

With v-sync it's 60fps. After reinstalling everything, the tearing (with vsync) seems to be gone, although it was intermittent before. Now I'm just left with 'jitter' - it only seems to happen on one computer - but quite severely. (I'm in touch with the manufacturers). The frame rate doesn't seem to reflect the jitter (i.e. it remains 60fps).

I thought one issue that might be causing problems is that I'm programmatically setting the view point's location and direction using a timer/callback. However, I've tried out some of the examples provided with vizard (such as winview), and they also have this 'jitter'.

I'm not sure if it's hardware, drivers or some other software. It probably isn't a problem with vizard, but it shows up particularly severly in vizard.

Any ideas would be good!

Thanks,

Mike.

[Jeff]

Did you learn anything after contacting the manufacturer? Have you used any other type of rendering application on that machine where you see the same thing?

[lionfish]

Thanks for the reply,
After going through a lot of reinstalling drivers, flashing BIOS(!), etc... ASUS are taking the laptop back/replacing it. I'm not convinced it'll help - but we'll see. I'm worried it might be a windows 7/64 bit/new drivers/Open GL/something like that issue - not sure.
I've tried a few other programs on the laptop with varying levels of flickeriness - they all seem to have the problem to an extent (especially Google Earth).

It wouldn't matter normally, but we want it for an experiment which may be relying on optic flow - so any disturbance like this could severely affect the results.

Thanks for the reply, I'll let you know how we get on!