mental ray FG flickering opacity maps?!

[ydiaz]

Hi, I ran into a similar problem once and came down to a different renderings of the same scene on different machines. One rig made the shadows of the opacity mapped objects broader than the other one, when combined there was a lot of flickering in the animation. I had to render everything on a single machine. Are you using a render farm?

[Slugger]

hi, no using a single machine(really wish i had a farm..), the bushes having problems are built lowpoly style, opacity mapped polys in a x-formation, did read somewhere that FG should be done on a single PC to avoid FG problems(or farmed out using buckets, then do beaty render with read only FG, but this doesn't really apply to my situation, must be something else). I guess the problems relates to mr's FG somehow, but how & why? samples/pixel is set to 4/16 and thats about how much I can afford, FG: diffuse bounces 1, the rest is pretty much default


*edit, found the problem, not a unusual error, I caused it myself, the x'ed polys are way to close to each other, therefore this flickering in the z-buffer when render,

cheers,

k.

[Kameleon]

You could try to put the blur in the cutout slot at 0.01, it worked for me in some ocasions.

[Slugger]

thanks Kameleon, will try that also, my self inflicted trouble caused by having the x'ed planes to close to each other was partially corrected by pulling them apart, but still some minor flickering,

*edit: "the blur in the cutout slot at 0.01" where can this be found?, looked around in the render tabs, could not find any cutout slot for mr?

cheers,


k.

[AnimG]

I had a flickering problem once and spent 3 days testing everything under the sun to sort it so can understand your anguish. It drove me potty!

Anyway,

The blur settings are under the bitmap map parameters, this is a good place to start as your working at the material level, not the entire image which is what sampling does.

I also reduced a lot of flicker by using the Gauss filter in mr sampling panel (softens textures) in conjunction with bitmap blur of 0.3 (defaults to 1) which made them sharper again and got optimum render speeds without losing too much quality and reducing flicker to almost none.

I have also found that flickering shadows can occur if a previously unlit area becomes lit when using FG maps (e.g. opening a door and looking inside) If your using the daylight system you can increase shadow samples (defaults to 8) directly in the daylight panel.

Displacement mapping (texture level) can cause a fliecker type effect if used with Saved FG maps when network rendering too.

Hope some of that helps, it was a while ago now.

Anim

[Slugger]

thanks AnimG, will have a look into those blur/sampling(it didn't occur to me to look at the bitmap level of things ie blur setting/filterning for those) settings and see if I can get rid of the last few annoying flcikers,

cheers,

k.

[AnimG]

thanks AnimG, will have a look into those blur/sampling(it didn't occur to me to look at the bitmap level of things ie blur setting/filterning for those) settings and see if I can get rid of the last few annoying flcikers,

cheers,

k.

How did you get on?

[Slugger]

hi AnimG, well all things done now, renderring proved to be a bottleneck with not that many try's, did rerender a few sequnces, but annyoing stuff all the same, ended up doing some retouching and using bits and peices masking out bad stuff with good renders of same frame in combustion, having a renderfarm of some sort will be a priority in the future(the one box I have(which is also my workstation) has done renders 24/7 for the past 1 1/2 months)

cheers,

k.

[AnimG]

hehe, that sounds like how I worked in my final year at uni. Glad all is well now.

Anim

[MikeBracken]

This is a bit off topic....but we stopped using opacity mapped trees/plants for the same reasons. We only use Onyx now. You can export all plants (trees, palms, flowers, etc.)
as geometry, eg., several different leaf/petal types. Not only do we not suffer from flickering, they also render a whole lot faster than with opacity. And if you also use the TreeStorm plugin, you can animate the plants. All in all I have to say that we are quite pleased with Onyx. We have used Xfrog, Speedtree, ect., in the past, and none have worked as well for us.



Regards,
Mike

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.