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Getting rid of grain in renders


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I have been doing a lot of night shots of a project that was started in VW 2015 involving a lot of spotlights and point sources with no environment lighting so I wasn't really expecting any grain.

Unfortunately I am reworking some renders in 2016 and the grain is terrible. It wasn't in 2015.

After scratching my head and trying everything I found that cranking up the anti aliasing was the problem.

This increases my render times by a factor of about 5 plus the notorious "Edges" phase takes forever so I'm not exactly thrilled with this answer....

This does not seem to be grain in the usual sense of the word because it is not caused by having environment lighting (i am not using any) and I am using indirect lighting (which was the solution if you were using environment lighting).

Is there another way around this that does not involve cranking up the anti aliasing because it is destroying my render times to the point where it is becoming infeasible AND

Why didn't this happen in VW 2015...?

I attach the renders from 2015 and 2016 to show the difference...

Edited by Mattheng
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indirect lighting is another word for global illumination, so it seems like what you are seeing is a low sample count in your renders. This causes splotches because the number of samples thrown out by the renderer is not enough to "connect the dots" so to speak. Have you tried turning up the indirect lighting?.

Environmental lighting is another word for HDRI or "sky object" which is to say that it's taking information from a picture for lighting information.

I think all lights will default to indirect lighting if you turn it on. I'm not sure you can turn off GI per lights.

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Thanks for the reply but I am a little confused.

Until now I only ever had grain when I used environment lighting ie an HDRI background and indirect lighting removed it completely. Possibly because it uses an irradiance cache but I could be wrong.

My main gripe is why 2016 is so much worse than 2015 but this is nothing to do with indirect lighting and I am saying that based on tests I have run. I thought it might be but it really isn't.

Changing the quality if indirect lighting does not get rid of the grain in this case where there is no environment lighting. Increasing the anti aliasing does but I do not know why...

Anyone.?

Jim?

Edited by Mattheng
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  • Vectorworks, Inc Employee

The settings values from one version to the other do not translate directly (so if you had everything on Medium in 2015 it would not look exactly the same in 2016) But it shouldnt be taking 5x as long as 2015 to render the same scene.

Send me that file at tech@vectorworks.net ATTN Jim and I can take a closer look, the 2015 version if you have it please so I can rule out conversion issues too.

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Jim, thanks for the offer but I am not allowed to send the file to anyone. It's a pain I know.

Also we do not have VW 2015 installed any more and there is no chance of it coming back either due to space restrictions so I cannot open the file in 2015 any more.

I appreciate that this is a pain and I wish I could do something about it but right now I can't.

The problems with clients....

I have done a bit more digging around and I can now safely say that :

1) If you are not using environment lighting, indirect lighting makes practically no difference to the grain because it only solves the grain FROM environment lighting, not point sources

2) The wall was textured with a rough texture which seems to require a higher anti aliasing to look smoother, so it isn't "grain" in the standard sense of the word

3) A bit embarrassing this one and I cannot check because we no longer have 2015 but I also did some daylight shots that were fine and when I checked the settings they had anti aliasing on high. They render a lot more quickly than the night time ones because there is only a heliodon and some environment lighting instead of all the point sources and I have a horrible feeling that I cranked the settings down to reduce the render time. Ahem

So I would like to apologise for wasting everyone's time, night time renders just are difficult and slow and I just have to live with it....@sigh@

Yours apologetically,

Matt

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Bump Mappings make GI harder.

Especially if you use GI with Irradiance Cache mode.

(As there is not much to cache when all neighbored Pixels are totally different)

Monte Carlo is better suited for detailed things like bumps or plants.

C4D Engine has more options for GI but it isn't very obvious which RW settings

will use which Mode. I think the interior modes will use IR/LM and normal modes

MC. So it is worth to play with the lighting and bounces settings.

Bump maps will need high AA settings and these will need more render time.

Also exterior daylight scenes are always easier for Gi calculations with light

coming from nearly all directions while interiors or your night scene has

very small lights that have to be detected, so you need much more rays to

detect them at all.

Maybe you can renounce of the Bump Map by faking the roughness by a diffuse

map only (?)

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  • Vectorworks, Inc Employee

Swap out the wall texture with a simple solid grey texture and see if the splotchiness is the same or more or less extreme, i had an issue recently with something similar to stucco as a texture causing this overly splotchy look.

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