HDRI and 'noise'

[Infinity3d4life]

You might take off Adaptive Sampling in the camera properties.. Try it like that and see if that works.. I had the same problem before and that fixed it up.. Hope that helps..

[JacquesD]

Blur it with 'full precision blur' in the image process panel, that might help.

[Baldric]

There are a few things that can go wrong

A. HDRI maps that have small 'bright' areas instead of being more evenly distributed. An example would be an HDRI map of a dark room with a skylight. The problem that arises is that fewer visible rays are being cast in the entire scene and those that are visible are coming from the bright area. If you want to keep the visible contrast that you're seeing in your render then you have to up your sample rate. If you're not to worried about changing your overall contrast then I suggest trying to alter the black and white points in the image editor until your blacks become more exposed and thus eliminate a lot of the noise.

B. Sometimes you can fix the above problem by altering the FP gamma of the HDRI, I know a lot ofd the HDRI probes out there are under exposed and should be put up to a gamma of 2.2 at least, so try that, it may even out the contrast a bit more.

C. If you see noisy edges... not much you can do about that, it's an unfortunate side effect in LW and of rendering in FP space in general. What happens is that FP values dont register at all on a monitor, so bright edges appear to exhibit aliasing... which they aren't really... it's a bit weird, you see it but it's not happening... the fix is again to alter your white point, try increasing it and you'll see a lot f the edge problems go away.

Remember that the biggest benefit of HDRI/FP is the unseen levels of exposure that it contains for each pixel, hence the large file size... it's possible to light something CG as if it we're night and the re-expose it in the FP image editor as if it were day, no banding.

Hope some of that helps...

Cheers

[miguel446]

Check this out. I thought maybe it was 6.5 or my G4 at work. But I came home and tried it 7.5 and got the same results. This is really bad. What am I forgetting.
I hear what you are saying about the white point, but do you really thing that would effect the image so drastically? Besides I got these from a really good source, who I think knew what he was doing.
Is this image in harmony with what your suggestions might fix?
I've got a date right now, but I'll try them when I get home tonight.

Check this out.

http://www.studiomiguel.com/images/hdrtest.jpg

Remember, there are NO textures on this, It's just a grey, subpatched model.

Good Grief!

[minus]

Yup..
Try bluring the HDRI in the image editor with the full precision blur set to about 3 or 4 on both settings.

That may help... but often times i've just seen bad HDRI's that you cannot make work in any software. It could be the origintal images that were used when they put together the final HDRI pic. -- One of those images could have been screwy.

Othertimes you can just have too many areas of very light and very dark... and things freak out unless you have your Rays Per Evaluation set at an altogether impossibly high setting.

Really I would just try a different HDRI. -- It's a good idea anyway to blur the hdri in the image filter since most HDRI's are so small... they strech when you see them in the background... the blur is better then streching... *and* a blured HDRI I think gives better results.

[MorBioS]

miguel you must turn on Antialising!!!!

If you don't like of render. try increase Ray per Evaluation ...


cya and good render man :thumbsup:

[miguel446]

Okay, Minus, Baldric, Ripper and Infinity. Thanks for your time and input on this. It seems, like most other really cool stuff in lightwave, that it is a quality setting issue.

I believe that no small part is attributed to blurring the heck out of the hdr image, which several of you mentioned. I didn't realize until Minus' post that you guys meant blur the HDR image. I was bluring my render! Go figure, what a moron!.
That helped.
Then I changed background. Biiiiiiiiiiiiiiiiig difference. So I blurred the HDR image again, this time LOTS. Then I cranked my Rays Per Evaluation up to 14x44. My render time bloomed from about 6 minutes to well over 20. But you can see the final results below.
I need to do some more refining to get to the quality level I need. But man is this slow.

http://www.studiomiguel.com/images/01_diff.jpg
different hdri used, blurred, intensity turned down to 70percent


http://www.studiomiguel.com/images/02_blrdltl.jpg
original hdri, blurred slightly w/ precision blur (7x7)

http://www.studiomiguel.com/images/03_blrdlt.jpg
original hdri, blurred LOTS w/ precision blur (25x25), RPE cranked up to 14x44

As you can see there was marked improvement. I am a true believer now that some images do not lend themselves as well to hdr.

Thanks ya'll. I'm now on my way to amazing renders.. I hope.

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.