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View Full Version : Best render settings to avoid noise in grass?



Sebasvideo
03-16-2014, 06:30 PM
I'm doing some test renders of a grass field, in particular the one that comes with the LW 11 content, which looks great. However, when I animate the camera to travel kind of sideways while at the same time pivoting to follow an object, the foreground looks great, but the background has a lot of noise that only shows when the camera is moving. A still frame looks perfect, but then the animation has noticeable noise in the grass that is far away.

My settings are not too low, I started yesterday and I kept raising the settings as I was seeing that there was no improvement, but I can't help but think that maybe I'm raising settings that don't need to and not raising the one that will make a difference. Because of past tests with similar issues but different scenes, I came to the conclusion that Gaussian will give the best results when it comes to noise, but it doesn't seem to help in this project.

I have Ray recursion and precision to 6, cutoff to 0.01, light and shading samples to 2, Radiosity off because it would take too long for this, min samples to 4 and max to 32. Threshold to 0.01 and oversample to 0, and Filter to Gaussian. These settings give me quite a long render time and didn't seem to do much for the background noise. Which of these settings would be best to get rid of that?

JonW
03-17-2014, 01:50 AM
I think you need to do 2 Photoreal motion blur passes, just leave the other MB setting as standard. As soon as the camera moves there will be more obvious noise, due simply to the camera moving, so the surfaces need MB.

Min samples 12 max 24 (upping the min should not add that much render time as the max passes will be quicker. This is also a better balance for noise on noisy surfaces as plainer surfaces)
RF Gaussian
SP Classic
AS 0.06 (because you have 2 MB passes this can be higher than 0.01, I usually use 0.03, & now double it to 0.06 because of the 2 MB passes)
Oversample (leave this on 0.0 with Gaussian or you will add noise!)

Doing 2 MB passes now effectively gives you 24/48 Samples which will be a much less noisy image.

Try a few frames at these setting & then see if you can cut back some of the numbers. But I think this is about as low as you can get as things start getting a lot noisier.

Sebasvideo
03-17-2014, 02:10 PM
Thanks for the advice, I'm trying those now. I'm not using my main machine because I have to work, just using three older machines so it's going to be several hours before I can see motion results. I was wondering, isn't there a way to avoid the MB and do something in After Effects that might get rid of the noise without blurring the whole picture? These settings obviously take quite a while per single frame.

JonW
03-17-2014, 03:12 PM
I believe there is something you can do in AE but I don't have it.

Since you are not doing radiosity, doing 2 MB passes is only going to take as long at the AA you are doing. So if you drop back the AA a bit to save time it may help. But I did fiddle around with these settings for a whole day & I think it is getting about as low as is reasonably possible. The fact that you have a fly through, noise it going to be a lot more obvious than in a still & unfortunately you really do not have much choice than to increase AA in one form or another.

Hieron
03-17-2014, 03:57 PM
Best setting ever for exactly that:
http://www.neatvideo.com/index.html
No doubt.

Just set AA to 12 or 16 and don't bother with any other tricks (this is noisy so AS will pick up a lot anyway and kill noise pattern on the side). Move into AE, sample noise pattern, no spatial filtration, 3 frame temporal, 40% treshold -> stable.

Sebasvideo
03-17-2014, 05:00 PM
I would have to take it into Premiere because that's where I have Neatvideo, but still I was doing some tests to do the grass in Element 3D instead, exporting the camera from Lightwave and rendering just the item I want to render, which should take considerably less time. My only problem with that approach is that I would lose the reflection of the grass on the device, which has the car paint surface on it. I have to check, but there is a way to make an object and its instances appear only in reflections but not on camera, right?

erikals
03-17-2014, 05:38 PM
tricky to fix afaik... other than what's posted above >

render double size, scale down, see if it solves things...

for clipmaps, increase the Ray recursion and precision a lot, not sure if it works the same way with instances...

in addition to NeatVideo, you could try After Effects RSMB as well, could help...

JonW
03-17-2014, 11:06 PM
What size image are you rendering & how many minutes per frame is your realistic target?

Here is 18 frames of the LW logo grass scene from a moving camera with the settings mentioned above. It's 19 minutes a frame on my W5580 x 2, about the same time as a 4930 CPU.

erikals
03-17-2014, 11:24 PM
the grass scene file if anyone wants to give it a shot... >

right-click, save as...
http://forums.newtek.com/attachment.php?attachmentid=110739&d=1359399236

Sebasvideo
03-17-2014, 11:49 PM
What size image are you rendering & how many minutes per frame is your realistic target?

Here is 18 frames of the LW logo grass scene from a moving camera with the settings mentioned above. It's 19 minutes a frame on my W5580 x 2, about the same time as a 4930 CPU.

I don't know yet, I will render 720p but how many minutes is not set in stone. It's something that if I can't render with my five machines I may convince the client to pay extra to send it to an online render farm. Or, I may do the grass in Element 3D, since the grass seems to be the bottleneck here. If I render without grass, at least on my 3930k, it's pretty fast, with grass it takes a lot longer.

But I have to experiment more with the grass, perhaps have 3 and a half million instances of each patch of grass in the content project, which makes that ten and half million total, is what's slowing it down so much. I know it's definitely slowing down my interaction and I have to disable that instancer to be able to work on the scene for even simple things like moving the camera. So I'm going to try to make bigger patches of grass and less instances, maybe that works. It worked when I went from one blade of grass instanced 50 million times to this, so maybe if I go higher with the grass and less instances it might work. Isn't there in the Lightwave reel something that had a lot of mountains and forest? I can't remember if it was Defiance or something else, but I remember seeing it. Of course those people probably have something way better than a 3930k and 32 GB of RAM to work with, but I want to give it a try anyway.

Thanks for the render, looks good, but the problem with the noise comes mostly when the camera has a lot of distant background.

erikals
03-18-2014, 12:11 AM
i'd definitely give lower AA a try, for then to use NeatVideo, you have it, so i would absolutely give it a shot.
or, why not?

JonW
03-18-2014, 12:54 AM
You need to work out now how many minutes per frame you need to finish the rendering. Then reduce that by another third for safety margin. There is no point doing this that & the other & not having enough time. Plus a bit more time for test renders.

Either you have to get more computers, render farm & or change things in the scene, & or render size. If the grass is in the background do you even need instances in these areas. An image should be good enough. Or thin out the instances to none after X metres & have a picture of grass.

Shiny_Mike
03-18-2014, 01:24 AM
I have to check, but there is a way to make an object and its instances appear only in reflections but not on camera, right?

Object properties -> render tab -> "Unseen by Camera"

what type of lights are you using? (possible source of grain?)

erikals
04-18-2014, 05:49 AM
Best setting ever for exactly that:
http://www.neatvideo.com/index.html
No doubt.

Just set AA to 12 or 16 and don't bother with any other tricks (this is noisy so AS will pick up a lot anyway and kill noise pattern on the side). Move into AE, sample noise pattern, no spatial filtration, 3 frame temporal, 40% treshold -> stable.

yep, minibump >
http://forums.newtek.com/showthread.php?101604-Grass-with-HDI-explanation-files

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