View Full Version : Post-blurry Reflections and Anisitropy?
06 June 2009, 08:05 AM
I have 4 questions
By the way its program independent.
1. Is there a way to fake blurry reflections by using a object pass (or colour ID pass) for a reflective object, then use another reflection pass and by using the object pass as a mask blur the reflection inside a compositing program? Maybe using an already blurred reflections but with bad sampling then post-re-blur it to eliminate the poor sampling? By the way its only for making surfaces like brushed aluminium (not complex surface, since the reflection pass would loose details by blurring) faster and noise-less (for animation)
2. Is there a way to use a normal pass to tell a compositing program in wich direction/perspective he should apply the blur?
3. If both my two questions can be answered, is there a way to make anisitropy speculars, or even change the angle of an anisitropic surface/spec/reflection by combining pass inside a compositing software?
4. Do the depth pass can be used for other purpose than just depth blur/fog/atmoshperic effects? Like combining the depth information with the normal information and use it as a more powerfull remapping tool?
Thanks for reading :)
(ps: sorry for my english mistakes im still learning it ^^)
06 June 2009, 09:35 AM
Mask the reflection pass with ID or whatever mattes and blur it.
You may use a normal pass to remap objects. An example for Shake can be found here (http://www.fxshare.com/shake/tutorials/general/UV-Map-Now-or-UV-Map-Later-129.html).
06 June 2009, 10:05 AM
Thanks for your fast answer (that blurred UV effect is awesome :D)
What if I make a cube, make it reflective like a mirror, then use an environement hdri (a desert with red sand and blue sky) and make a render where you see 3 sides of the cube (up, right and left) using a camera angle that mimic an isometric camera.
The up side gonna be blue, the left and right gonna have red tones.
When im gonna blur all the reflections in post the up side will bleed on the right side, each side gonna bleed on each others. The up side gonna be blue and purple, the left side too, the right side also, and in the middle corner when all the sides meet gonna be a mess!
If it was a sphere, no problem will be visible. But its a cube :)
I know I can make 3 object mask one for each side of the cube, but what if my cube has round corners or what if its a kind of organic shape like you see a lot in jewelry? I also know that I can blur the hdri, it would help a little but what if its not lighted by an hdri :)
This is just a basic example. I wanna know if there's a way to bypass that by somehow using a normal pass, the normal pass would say "hey this side is there, the bevel is that large, dont bleed too much on that side because its another side than this one"
06 June 2009, 12:54 PM
WHY, do you want to blur it in post. It will never be as accurate as raytracing it. Or faking it with blurred reflection maps?
06 June 2009, 01:46 PM
Mainly for animation because I use cinema 4d and unlike vray its much slower for blurry reflections :)
Of course using raytracing is needed but maybe with low settings.
Since every work I do need post production why not taking advantage of this step and improving the noise/flicker of blurry reflections?
Ive watched the SWAP demo from random control (fryrender) and I want to mimic what they do with a dedicated software that use informations from the render but using classic pass.
(ps: Im very curious also, maybe I ask questions for things that I will not use a lot, who knows)
06 June 2009, 11:40 PM
In case of a simple geometry you could use an object space normal map as an object id pass and blur that once for each visible side of the object.
Not that I would recommend this workflow...
07 July 2009, 07:10 AM
Wow its you Stefan Minning! (I was looking your website just before I logged into cgsociety right now hehe)
Im amazed about Normality 3 wich is kinda related with normals, and I also like very much your cartoon style (reminds me Jeremy Vickery in term of color mastering) also im a huge gamer but ive not played Frontlines (maybe I should)
I readed and watched a lot about using normals and re-lighting, reflections are of course differents but maybe one day every major 3D programs gonna mimic what random control SWAP does, using all the informations recolted in the render process to quickly make changes. Multi-lights, Automatic objects ID, built in vector pass and depth pass etc...
Well, post blurring reflections only works in special cases ok, and what about spec or anisitropic? Is there a way to generate the specular and change the angle in post?
Thanks for all the feedback :)
(ps: Stefan your website is shouting at me "use maya" :D)
07 July 2009, 03:19 PM
Is there a way to generate the specular and change the angle in post?
Well, you can very easily create a spec with Normality (http://www.minning.de/software/normality). You can't change one that's already been rendered, of course. It handles blurry reflections as well, by the way.
It also works fine with normal maps from C4D.
Other than the already mentioned SWAP, I don't think the type of software you area looking for is publicly available today. Trying to recreate the functionality of SWAP without programming will not go far.
Not to toot my own horn, but Normality is in fact the closest I can think of... :shrug:
07 July 2009, 03:19 PM
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