vray specific AA filters.

[super gnu]

there is absolutely zero documentation ive found for these.. which ones are good for what? how are they different from the max ones?


as a connected issue, ive noticed the spot3d help pages are starting to get a little patchy, particularly where the new features are concerned.. very often recently ive seen vlado suggesting tips and tricks which really should be in the help files, but it doesnt really get updated much at all..

[Morne]

dont worry, soon they'll employ Ken and all will be "sorted out"

[super gnu]

nope.. dont understand.. thought about it for ages but still dont understand. :P

[instinct]

I assume it is meant to be an ironic comment towards Ken Pimentel of Autodesk (for the record, personally i think he does quite a good job and things have gotten HEAPS better than they used to)

Regarding the AA filters, they are not VRay specific as in "invented by chaos" and there is general info available on them:

http://en.wikipedia.org/wiki/Lanczos_resampling
http://en.wikipedia.org/wiki/Sinc

a Box filter is, well a box filter and triangle is...well a triangle filter (which corresponds to pyramidal in max's texture filtering if i am not mistaken)

Regards,
Thorsten

[super gnu]

thanks for the links.. very.. technical

what i was really after.. is, is are any of them very good at reducing distance shimmer in aa during animation...? ive heard lots of opinions about which filter to use.. some say use a blurring filter, others say use no filter as it renders faster, so you can use lower noise threshold.. etc..
from my testing the time saved not using filtering isnt nearly enough to afford increasing sampling quality significantly.. but hey it probably depends on the scene.

[joconnell]

Here's a decent one which isn't too technical - http://www.artbycrunk.com/blog/resea...ters-sampling/ so pretty much the curve shows you a pixel that lies along the edge of an object and when sub sampling happens the curves represent how each filter blends between your edge and the colour values outside that edge.

Oh and shimmer is a bastard since even if you're using exceptionally high anti aliasing values, the correct values could actually be something that looks like grain - vray will always see this as the right solution, even though if you have a slow creeping camera move for example, it'll cause pixel shimmer. Catmull and mitchell will make contrast along the edges of objects or detail more contrasty so they're bad overall, no filtering won't intensify contrast so that's slightly better, and then the blurry filters like soften and quadratic will reduce edge contrast so that'll smooth out pixel shimmer again. In this case motion blur is often your only move to smudge out those details, especially on things like distant tree renders where leaf size detail can often end up being smaller than 1 pixel.

[priad]

great and useful link !
thx for sharing.

[Deflaminis]

I am by no means an authority on this, but I have done a lot of research into it. That's the problem with finding info in rendering, each person has their own workflow which has many cascading repercussions and strangely related results.

I would try these filters first and see if any help clean it up: (These are how I use these, but are no means the actual technical definitions of them.) Your mileage may vary...

Cook: Good way to blend between terrible moire patterns vs. smooth distance fade. Sometimes it's just horrible for what you're doing, sometimes it fixes things wonderfully. (Circle patterns heading into infinity love this). Other good filters for the moire patterns are: Cubic, Area, Soften, Video, Blend. When to use them would depend on what is going on in your scene, if there are characters for example or particle effects.)

Catmull Rom: Good at bringing out those bumps in dark areas where you just can't see anything worthwhile. Will create terrible dark edges on reflective materials in vray 1.5, however I understand there is a way to fix this in vray 2. (A checkbox on the material I think, could be off here, haven't had a chance to try it.)

Blend: Favorite for fixing overbright pixels, especially in glass. (Only really an issue with LWF and 32bit renders.) Makes things look blurry sometimes...

No Filter: Does render faster (of course), however if you are rendering with no clamped colors you're going to be upset with the results. With clamping it'll look a lot better. I don't know if you've used Solid rocks, but it's probably the best program for learning the ins and outs of the filterless workflow, at least in seeing how everything sort of binds together. (And it's cheap.)

The vraysinc filter seems pretty nice for interiors, but I haven't tried it outside.

The shimmer can be from all kinds of things. I've had projects where my render times for background objects just took way way too long, and created a shimmer or wavy pattern in motion. Turned out I was antialiasing all those objects way back and ended up doing it based on color threshold instead of geo subdivision and it helped a lot. The hard part is identifying what is causing the shimmer, as opposed to which filter covers up the problem.

[crazy homeless guy]

I am by no means an authority on this, but I have done a lot of research into it. That's the problem with finding info in rendering, each person has their own workflow which has many cascading repercussions and strangely related results.

I would try these filters first and see if any help clean it up: (These are how I use these, but are no means the actual technical definitions of them.) Your mileage may vary...

Cook: Good way to blend between terrible moire patterns vs. smooth distance fade. Sometimes it's just horrible for what you're doing, sometimes it fixes things wonderfully. (Circle patterns heading into infinity love this). Other good filters for the moire patterns are: Cubic, Area, Soften, Video, Blend. When to use them would depend on what is going on in your scene, if there are characters for example or particle effects.)

Catmull Rom: Good at bringing out those bumps in dark areas where you just can't see anything worthwhile. Will create terrible dark edges on reflective materials in vray 1.5, however I understand there is a way to fix this in vray 2. (A checkbox on the material I think, could be off here, haven't had a chance to try it.)

Blend: Favorite for fixing overbright pixels, especially in glass. (Only really an issue with LWF and 32bit renders.) Makes things look blurry sometimes...

No Filter: Does render faster (of course), however if you are rendering with no clamped colors you're going to be upset with the results. With clamping it'll look a lot better. I don't know if you've used Solid rocks, but it's probably the best program for learning the ins and outs of the filterless workflow, at least in seeing how everything sort of binds together. (And it's cheap.)

The vraysinc filter seems pretty nice for interiors, but I haven't tried it outside.

The shimmer can be from all kinds of things. I've had projects where my render times for background objects just took way way too long, and created a shimmer or wavy pattern in motion. Turned out I was antialiasing all those objects way back and ended up doing it based on color threshold instead of geo subdivision and it helped a lot. The hard part is identifying what is causing the shimmer, as opposed to which filter covers up the problem.

Nice post.

[beestee]

Could some very slight DOF settings be used to blur the distant detail just enough to minimize or kill the sub-pixel crawl? I know motion blur is used for this sometimes, but in the case as mentioned where the pans are very slow, motion blur would seem a little more difficult to control.

Might do some tests with this myself since I have some time

[werticus]

I'm doing some research into this soon. I've noticed the vray specific filters are faster - fairly significantly. At the moment I use CUBIC for video - as it seems to be the most shimmer resistant. It is pretty blurry as far as they go - but if im doing a camera match i usually need to make things even blurrier.