View Full Version : Backdrop Image AA?

04-13-2009, 08:57 AM
Is there an option I'm not seeing to TURN OFF backdrop image AA when using Adaptive Sampling? It slows renders down to a crawl, because Adaptive is still "seeing" the need to AA it, even though I assume it actually isn't being AA'd to the render buffer, so massive quantities of pixels are being resampled for no good reason.


04-13-2009, 08:27 PM
No there's no such option. It would be nice to be able to set aa per object.

Just render over black and composite the bg afterwards. Quicktime or Layout can do that much, quickly and easily.

Thanks for pointing that out, I thought it would either aa the background or ignore it, it doesn't affect it no matter how much resampling takes place.

04-14-2009, 10:18 AM
Yep... that's what I ended up doing... rendering over black (no BG img seq), saving out to PNG-32, and comping the BG in AE.

In doing so, it appears that there's a massive Alpha bug still present in 9.6 in dealing with multiple transparently surfaced objects (just simple planes in my case). The bug happens when OBJECT DISSOLVE for one or both objects is set less than 0%. The foreground object will show in the alpha with totally whacked out alpha... like some sort of threshold is being used. That is, I have two planes trans mapped with the same b/w gradient image, one plane smaller and in front of the other, and both with a dissolve envelope. The alpha of the FG plane shows the whole (square) object with a "hole".

The only way I could resolve the issue was to remove the dissolve env (back to 0%) and use it as a Layer Opacity env on the transparency img map texture.

No combination of options (exclude from V-stack, rt transparency, rt refraction [with 1.001 refract index added to surfaces], etc.) made any visual difference in the alpha. It wasn't until I put dissolve to 0% for the FG plane did the alpha render correctly. Put it at 0.01% and bang... whole plane visible in alpha with a hole where the gradient the of img map was full black, that is, the alpha didn't render the gradient of the image, just a sharp edge where the image changed from 000 black to 111. Put dissolve to 99.9% with no change in alpha. Of course, RGB was rendering correctly.

Guess I'll have to make time to make a bug report content scene and fog this.


04-14-2009, 03:10 PM
Yea LW isn't exactly comp friendly :mad:
So it's a combo of transparency and dissolve, not clip mapping? Clip mapping won't show gradients, only black or white alpha -

04-15-2009, 03:35 PM
This topic has strayed way away from my original topic, but for what it's worth to others, I submitted the Object Dissolve Alpha cockroach with movie and scene content to Fogbuz...
Case 22301 (https://secure.newtek.com/FogBugz/default.asp?pg=pgPublicView&sTicket=22301_4331).