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View Full Version : compositing glass problem: URGENT

AroundTheFur
08-11-2003, 08:46 PM
so ive been working on this office flyaround, and i got this nasty flicker on the ground texture that i cant seem to work out. so in the scene, im replacing the ground with just a flat color, and every thing else's matte opacity is set to black hole, so it will still block areas of the floor that need to, and still cast shadows.

here is the problem. i have glass in the scene, and if i just render the glass in there also it will not reflect and refract the objects in the scene, because their opacity is set to black hole. so i tried turning off primary visibility on everything but the glass for a seperate pass, but, now the glass isn't blocked by object that are in front of it.

im sure there is an inbetween here that ive missed, but recapping, i need a way for the glass to reflect and refract everything in the scene, but be blocked when objects are in front of it. this is VERY urgent. thanks for any help!!
AroundTheFur
08-12-2003, 01:36 PM
is this unlcear? i would think itd be fairly simple. a material or checkbox ive overlooked?
alexx
08-12-2003, 02:13 PM
not that i really spent too much time thinking about it:
how about rendering a seperate alpha pass (the one for the blocking)?

cheers

alexx
AroundTheFur
08-12-2003, 02:23 PM
im not sure i really understand what you mean. i would have the floor pass, the glass pass, and how would this seperate alpha(i assume you mean the matte for the glass) make it appear as though the glass is being blocked. how would i go about setting up this scene is what i guess i mean. thanks.
alexx
08-12-2003, 02:28 PM
render your glass with all other objects have prim visibility off, and then render a pass, where the glass has the same shader (for transparency (which it should not have when refracting)) and the other objects with the black hole shader.

render your other objects without the glass as well..

now you can take your all objects render as a background.
copy the alpha from the black hole render to the reflection render and the just copy the result over the rest..

should work

cheers

alexx
AroundTheFur
08-12-2003, 02:55 PM
ugh, this thing is due tomorrow, and i dont think i have time to do all that rendering, i think im just gonna have to lay the floor on top and leave whats behind the glass stay. it sucks, but thats really all i can do.

the problem i was having was the texture was flickering like crazy. i got pixho's scripts for filtering based on camera distance and i think they made it worse. why do maya's textures flicker when the repeat uv is upped a lot?
alexx
08-12-2003, 03:03 PM
sampling quality in maya is an old issue..
i found that e.g. mental ray is way better in those cases.. gets slow then but at least it is possible to get a good rendering.
in maya in some cases even 20/20 for aa settings does not help in maya.

sorry i could not help..

cheers

alexx
AroundTheFur
08-12-2003, 03:17 PM
thanks for the help though. its always appreciated =)
BigSky
08-12-2003, 05:17 PM
You can always try rendering double size without ani-aliasing, then filter down as a batch in photoshop (bicubic). This often helps with this kind of thing.

;)
AroundTheFur
08-13-2003, 03:26 PM
i really dont see how that has anything to do with my problem, and since time is an issue rendering double size really wont help. luckily, i may get by just comping the floor without the reflections and refractions, it seems to look ok.
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