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IRML
01-18-2011, 02:21 PM
funny problem with ani-reflections here

the first bounce renders fine, but it appears the second bounce renders as if the first has no blur and no reflections at all

here's my test render, you can already see there's a problem with it

91973

the same render but a surface has been seperated and the ani reflections set to have 0.01% blur (not 0% blur - another error, I'll explain at the bottom), and you can see the problematic reflection is exactly the same

91974

interestingly if I just put a standard reflection shader on that seperate surface it blurs ok - so it seems to me that the problem is ani-reflections having trouble with reflecting other ani-reflections?!?

also if I put no blur at all on the ani reflections I get this

91975

something looks quite dodgy with this shader, is it just me? I've attached the scene and objects below

IgnusFast
01-18-2011, 03:15 PM
There have been some threads here on issues with blurry reflections. I think Tobian had a lot of issues with his space station and LW blurred reflections. I won't retread those, mostly because I didn't really follow them. :)

It looks to me like a side-effect of a shortcut that the node is taking to calculate the reflections - I say that because from the surface angle of the faces involved, that really shouldn't be reflecting there at all.

I don't do much with nodes, so this might not be very helpful. And it does tend to be noisier. But I just simulate the effect by adding a micro-bump to the surface, and an incidence angle to the reflections. You might be able to use something like this. And it renders a LOT quicker than that node setup does, at least on my machine.

Here's the resulting image and the surface (basically the same as yours; the only difference is the new base attributes and the fact that nodes have been turned off):

IRML
01-18-2011, 03:18 PM
trust me microbumps aren't quicker, it's the only reason I'm trying out the ani-reflections node, they might seem quicker because you're getting much less blur from them, if you increased the blur and wanted results as smooth as the ani-reflections node you'd be rendering like 20x longer

I'm looking at other ways of solving this, you're right it could be a shortcut the node is taking, I just don't know but I'll post if I find out

according to tobian the colour issue is fixed in LW10, but the blur is still dodgy, he rendered some tests a few minutes ago but hasn't posted them here

IgnusFast
01-18-2011, 03:31 PM
Odd. The microbumps rendered in ~9 seconds on my quad - the nodes took ~24. But I can understand that they could be slower in different circumstances, especially if you had to get them really smooth. I'll have to play with that node in one of my complicated scenes and see how well it works.

IRML
01-18-2011, 03:42 PM
yeah there's barely any blur on yours though, try increasing it to the levels in my first setup and the grain will be very bad, requiring higher AA to fix

the problem with microbumps is the surface is doing all the blurring, so you don't get samples like you do with the reflection shaders, so the AA has a very hard time ironing out the grain, which is why I'm trying to use ani-reflections because it's super fast, even faster than standard reflection blur is some cases

Tobian
01-18-2011, 03:55 PM
Yeah micribumps are always slower than reflection blur, as the whole surface has to be re-evaluated, as opposed to just the reflection shader. The bug with the colour is partially cleared up in LW10 - but the blurring depth error doesn't seem to be (it's showing green but not correctly blurring in the aniso shader) The DP shader works fine, though, but it can be slow and has the same noisy issue for any smeared reflection shader like that, the further from the object you go. Would be nice if Lw had a faster way to generate reflection blurs, like an irradiation cache sample or point cloud etc.