Render strips banding problem

[tricky]

Since upgrading to 1.5, whenever we do a strip rendering of a high res image, the bands are very noticable, particularly on interior shots, but also on exteriors to a degree. I'm pretty positive on previous versions we had no problems like this - certainly on exteriors we had absolutely no problems.

Our settings are pretty much as before as well - Medium IRmap and 1000 or 1500 LC samples.

I know we could precalc the solution, but as this worked fine before, I wonder what setting I should be changing to get it to work now.

Any one else have this? Apologies if this has cropped up elsewhere - I've had a trawl but not found anything yet.

[Clifton Santiago]

I've had this problem as well, but its not consistent. Strip rendering will work well on one file, but not on another. The only thing that sometimes helps is manually stopping and restarting the backburner service on each render node individually.

[tricky]

Anyone else having this? It really is a problem for us as we can only rely on one machine to one job at the minute rather than using our entire render farm.

[jacksc02]

tricky, i would pre-calc you GI on 1 machine. It is just safer to do.
You can set up a dependency in BB to let the strips render once the GI calcs are done so your not wasting a nights render

[MegaPixel]

I always get some degree of banding when using LC or IR but never with QMC. You need to precalc for LC and IR if you want to eliminate the possibilty.

[Clifton Santiago]

Uh... we're not a newbies...

Everyone knows about precalcing your IR and LC on a single machine. What I was referring to (and I assume tricky as well) is the inconsistent performance of 1.5 with backburner strip rendering. Even with precalc'd solutions you now will get occasional banding on backburner. All maps, bitmaps, .vrmaps, .vrlmaps are UNC mapped correctly, and still there are occasional banding problems on one or two machines. Sometimes reseting the backburner service on the offending nodes will solve the problem, but not always. Sometimes the banding error will then start on another node that wasn't doing it previously.

I never had this problem with 1.47.

[tricky]

Uh... we're not a newbies...

Ohh-err!

Yes - precalced solutions will of course work, but on 4000pixel images the solutions can take a good while. Splitting the images means we can have full-res drafts in half an hour!

Comment from the Chaos team?

(though I must admit Clifton that I have never noticed banding with saved solutions at all - though I can't say I have done much testing with this method as strip rendering has always worked (externally at least) for us with the solution calculation as well with older versions)

[tricky]

c'mon Chaos - any answers on this?

[biglolly]

I'm having this problem too...only noticed it with LC. Found myself photoshopping a few images to remove the banding - rubbish fun!

Haven't tried the pre-calc solution, but I can imagine it would take some time on 4k+ renders.

[Clifton Santiago]

You almost always have to precalc IR/LC on one machine, when strip rendering to backburner, unless you have a very bright, open scene. You will get severe banding in darker areas or where there are contact shadows (like interiors). This is because they are approximate methods and each machine will calculate slightly differently. For the same reason, this method is unsuitable for animations with moving objects.

You can sometimes get away with IR/QMC without precalcing, especially for exteriors. But IR/LC is significantly faster, and I have switched to it even for exteriors now.

[tricky]

You almost always have to precalc IR/LC on one machine, when strip rendering to backburner, unless you have a very bright, open scene. You will get severe banding in darker areas or where there are contact shadows (like interiors). This is because they are approximate methods and each machine will calculate slightly differently. For the same reason, this method is unsuitable for animations with moving objects.

I have been aware of this and have never really had success with interior strip renders for interiors. However, we used strip renderings for exteriors 95% of the time before, but with Vray1.5 we get banding even with these.

[vlado]

I've been unable to reproduce that on my simple tests here; it would be best if you can get me a scene where I can reproduce this and email it to vlado@chaosgroup.com so that I can check what may be wrong.

Best regards,
Vlado

[Arkitec]

Was there any resolution to this?

I'm having problems creating the LC on one machine, out of ram issue. What Ive been doing is running it through BB on one machine for a working around using strips. But its completely defeating the purpose.

The scene I'm working on is poly intensive.

Are there any other ways to get rid of the banding.

I am working on an interior image, but I don't think it matters. Still occurs when doing exterior and happens more times than not.

Arkitec

[Arkitec]

Was there any resolution to this?

I'm having problems creating the LC on one machine, out of ram issue. What Ive been doing is running it through BB on one machine for a working around using strips. But its completely defeating the purpose.

The scene I'm working on is poly intensive.

Are there any other ways to get rid of the banding.

I am working on an interior image, but I don't think it matters. Still occurs when doing exterior and happens more times than not. I too didn't notice it as much, but on high res images 4k and bigger - very noticeable.

Im rendering a highres test with DMC now....

Arkitec

[Neilg]

Ive always had banding from LC strip renders, Q/DMC and IR is the only one that ive seen work reliably.

When pre-calculating, do it to 1000px wide and turn your IR settings up to high. Much faster, and higher quality.