PDA

View Full Version : mib_amb_occlusion and color bleed


Arcon
11-03-2005, 11:22 AM
with the cool mib_amb_occlusion shader... it goes part of the way to not needing final gather for some scenes, is there such a quick fix solution for color bleed...? (that's useable in animation like the ao shader). or maybe a way of configuring an ao network so it can give this effect?

dagon1978
11-03-2005, 02:00 PM
yeah... use the fg for AO :p

eheh

Osaires
11-03-2005, 03:09 PM
or check out this treath http://forums.cgsociety.org/showthread.php?t=199100&page=2&pp=15, but the shader is not done yet though

Arcon
11-03-2005, 08:18 PM
yeah... use the fg for AO :p

eheh

heh except FG is not usable in animation :thumbsup:

(at least animation that involves more than just camera movement) :shrug:

ajsfuxor
11-03-2005, 10:58 PM
I use FG in animation all the time!! Maybe before MR 3.4 it wasn't overly useable, but I use it for all my animations.

Arcon
11-04-2005, 12:53 AM
I use FG in animation all the time!! Maybe before MR 3.4 it wasn't overly useable, but I use it for all my animations.

if you're using it on big projects with animated objects (not just camera), you must have a helluva renderfarm ;)

revilo3D
11-04-2005, 01:07 AM
whoa hang on... coorect me if im wrong but

FG for AO is the final gathers filtering algorithm to smooth lower sampling rates - no bouncing of light/color bleeding there.

FG is perfectly useable in animation - you just gotta know how to play it smart - and learn some compositing to make it even easier. Im rendering an aniamtion of 5-6 full animated objects using FG as we speak.

One way i do it bake my lighting to texture - or go around my scene before hand and collect fg points before i freeze the map and render my animtion pass... then chacracters are rendered in seperate passes - witha AO pass and or sahdow passes over the whole lot to make it gel :)

Its isnt entirely accurate as light info for characters dont bleed into BG but i bet youd hardly notice.

works for me..

Arcon
11-04-2005, 07:35 AM
FG is perfectly useable in animation - you just gotta know how to play it smart - and learn some compositing to make it even easier. Im rendering an aniamtion of 5-6 full animated objects using FG as we speak.

One way i do it bake my lighting to texture - or go around my scene before hand and collect fg points before i freeze the map and render my animtion pass... then chacracters are rendered in seperate passes - witha AO pass and or sahdow passes over the whole lot to make it gel :)



we've used FG baking to texture before but on larger scenes that have 5,000 plus objects it can use a lot of production time tweaking textures and UVs. to avoid this we use the freeze option for obejcts that don't move (camera-only animation) - its a good method. but you can't use it for objects that move because the FG colors gets left behind on the neighbouring surfaces, for that we render the niamted object seperately and fake radiosity effects for it (if needed). FG without freeze might be usable in animation with the rays and ratios at he right values, but rebuilding the map *every frame* on the size of scenes we work with, we'd need at least 10 dual-core machines, we'll get there but we ain't there yet ;)

another thing about the ao pass is the effect won't show up in reflections, like a mirror surface (unless there's another way of doing it... which would be cool, in which case please tell me lol :) ). for a lot of animations with subtle reflections you wouldn't notice it but for high-end architecture, they notice.

i've done quite a bit of testing with multi-pass and when you have reflections that need all the information, its actually very similar rendering times when rendering in one single pass with FG (with freeze), and then there's the time saved in production with configuring less passes.

revilo3D
11-04-2005, 12:00 PM
mmm.. there is an advanced techinque fro gerating AO using it as a light shader or something..

check section 1.5 of this doc...

http://www.lamrug.org/resources/doc/occlusion_tutorial.pdf

i think this maybe will show up in reflections. dunno - worth a shot.

Saturn
11-04-2005, 01:13 PM
Create an environmeent picture of your digital set.

And use it in the the pass with your animated object.

bgawboy
11-04-2005, 02:48 PM
As pointed out in the occlusion tutorial referenced above, FG occlusion will take into account color bleeding.

Most AO shaders call probe rays which do not call the material which they hit, whereas FG rays do call the materials they hit. So occlusion from FG can incorporate multiple bounce occlusion and light paths.

CGTalk Moderation
11-04-2005, 02:48 PM
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.