OpenGL – interactive, always on or Adaptive Resolution?

[Chris Smith]

Not for render times. It’s for real time interactivity. When you are using a lot of 3D layers it’s a good idea to switch to OpenGL so that when you move the camera, the layers are converted to OpenGL and the GPU of the render card takes over doing what it does best. So the result is that you will see the layers move with full interactivity. But things like DOF, blurs and a lot of non-supported things in OpenGL gets turned off. It’s just like a video game. Video Games program everything to work whithin OpenGL so it’s fast but you lose a lot of rasterized render effects.

Adaptive resolution shows you every single effect you applied just as you have it, and it tries to speed up interactivity by adaptively lowering the resolution while the playhead scrubs or you move the camera. But it’s slow because it uses the CPU and accounts for every single effect you have creating your comp.

So for example if you are doing every noobies favorite first AE project, putting pictures in 3D space then using DOF, you would set it to OpenGL while placing the pictures and animating the camera, but then switch to adaptive resolution when tweaking the DOF since OpenGL doesn’t support DOF.

But at the end of the day, no matter what setting you have it on, RAM previews and render outs are always rendered the same from the CPU.

[Adolfo Rozenfeld]

Chris:
With all (huge) respect, I believe the description you gave was true for previous versions of After Effects. And it’s still accurate for the current version, if you don’t have a really high end graphics card.
BUT in After Effects 7.0, if you have one of the really powerful cards that support things like anti-aliasing and Motion Blur, AE gives you the choice of using the GPU for processing those during RAM previews and also final renders. That’s what “Always” means – enable OpenGL procesing for RAM previews. We got to the point where a Geforce 7900, ATI X850 or X1900 or QuadroFX will process those things with identical quality. Oddly, the power of the graphics cards is platform dependent. You may get better results with one brand on Mac and the other brand on Windows, despite them having similar horsepower.
To enable it for final renders, you have to check the “Enable OpenGL renderer” in the Render Settings. Of course, not even middle of the road cards like the 256 MB Radeon X1600 in my MacBook Pro will produce a final render with good results, since it lacks the features Adobe calls “high quality OpenGL” or something like that (basically, the ability to produce anti-aliased output),

Adolfo Rozenfeld
Buenos Aires – Argentina
https://www.adolforozenfeld.com
adolfo(AT)adolforozenfeld.com

[Chris Smith]

Very cool. Didn’t know that. I figured it was a matter of time.

[Jimmy Brunger]

Cheers for the input guys.

So, to my understanding, with my system (GeForce5200, 2.4GHz p4 – 3GHZ by next wk – 2GB RAM, WinXP32) It’s probably not really worth using OpenGL unless I have LOADS of 3d layers, lights and cams?
I mean, I switched between orbiting camera realtime with Adapt res vs OpenGL and there wasn’t really much difference in speed and the OGL just took off anti-alaising, plus scrubbing the playhead took a while to refresh.

With a Quadro FX or similar then, does it in fact act as somesort of hrardware acceleration for AFX? Does it free up more power for the processor to handle other stuff when using OpenGL, hence speeding up RAM prevs?

So, I’d need a pretty good GFX card to see some noticable difference using OGL I guess..I’m a bit limited by my motherboard at the mo, but hopefully soon a new system will be a poss and I’ll make sure it’s upto spec (I’ll probably be back for advice then!)

The other thing – what are people’s opinions on the 3GB switch? I don’t know whether to opt for another 1-2 gigs RAM… (It’s Dual-Chan DDR400)

Thanks.

[Chris Smith]

It doesn’t have to be a situation where you have tons of 3D layers. The opposite could be only a handful of layers, but you have so many effects in the comp that the adaptive slows way down trying to render them.