IRAY Rendering (and maybe Lighting) Question(s)

DrowElfMorwen

I'd like to include an image I have been working on. Below, on the left, the image only took maybe an hour or less to render like this (if I recall correctly). The image on the right, I am still rendering, and this screencap was captured after 9 hours of rendering. I simply changed it by adding a distant light to the left set up, to act as a rim, and then I added bloom.

My question is, what can I do to speed up the render time in this case? Is my figure not well lit enough, and that's why she is still so grainy?

Oh, which leads me to my second question. I want to use Depth of Field to blur most except her which I did in both images (the camera settings are exactly the same). Now she isn't as clear as I'd like her to be, she seems too soft in both images--should I try rendering larger? Also, in the right hand image, though I much prefer this lighting, she has suddenly become... hazy, especially in her face, and by her armband. What causes this and how can I fix it?

After 9 hours I'm afraid to stop the render, but I also want to fix it >.> (and possibly get better results faster).

Thank you for any help!

evilded777

I don't think distant lights really work with iRay. I find their usage to be unpredictable. I'd recommend a spotlight instead.

Can't help you with DOF as it is still a black box to me.

DrowElfMorwen

The distant light is actually behaving wonderfully for me in this situation. I only wonder how I can make her not look so ... pale? And grainy. But then, she is supposed to be in partial shade.

mjc1016

Well, the first thing to do is to look at it as if it were a photograph and all the automatic settings on the camera were broken.

It's obviously overexposed.

So you'll need to adjust either the light (turn it way down) or adjust the exposure settings. Or a combination of both...

Distant lights in Iray are rather tricky little beasts. They don't need the 'power' of other lights...so they'll need to be turned way down to prevent 'blowouts'.

Also, while the HDR used is giving light, it's not doing a good job with shadows...which usually means that there isn't enough range to the image. (There's also the chance that the HDR isn't actually contributing any light to the scene and all you are getting is the camera's headlight...I'm not decided on this one, though.)

And it looks like the image may have not 'cooked' long enough. If it had, the, now present, shadows would not be so grainy (the light areas might be, due to being over exposed).

DrowElfMorwen

mjc1016 said:

It's obviously overexposed.

Okay... look, if it was obvious, I wouldn't be asking the question. If it was obvious, I would have fixed it.

Besides, the lighting to me is perfect, for the environment. I don't want to change it, I love how bright it is. So it doesn't explain why she is so grainy. Doesn't graininess happen only when you don't have enough light and the shutter speed is too fast to capture it?

Now, I did go in and lower the exposure vlaue/shutter speed. This resulted in a very brightened picture. Then I upped it, a lot. It looks nice, but not too different than before. She still is taking a long time to get over her graininess compared to everything else in the photo.

I understand too that she is also sitting in shade, so perhaps this is a factor?

yinliang9

DrowElfMorwen said:

Besides, the lighting to me is perfect, for the environment. I don't want to change it, I love how bright it is. So it doesn't explain why she is so grainy. Doesn't graininess happen only when you don't have enough light and the shutter speed is too fast to capture it?

Now, I did go in and lower the exposure vlaue/shutter speed. This resulted in a very brightened picture. Then I upped it, a lot. It looks nice, but not too different than before. She still is taking a long time to get over her graininess compared to everything else in the photo.

I understand too that she is also sitting in shade, so perhaps this is a factor?

It's true that graininess happens with too little light, but I've never really had that happen with Iray; that was more a 3Delight thing. Usually with me, pretty much any kind of graininess eventually goes away with Iray renders if they're given enough time to "develop". It's not an absolute, though, so I can't be sure that's the issue here (especially if this is rendered to 100%).

As far as the blur... I'm not 100% sure, but it LOOKS like it could be a depth of field issue. Are you sure the focus is precisely where you want it? Then again, you said the camera is identical in both shots, so it shouldn't be the case... If nothing else fixes it, however, you could try pulling the focal distance back slightly and see if that helps.

You don't have the bloom filter enabled, do you? If so, that's a VERY likely cause, but bloom requires fiddling with settings per picture to get to look perfect, so unfortunately I couldn't give you a direct value to input there. :|

Edit: Aha, just reread your OP! The bloom filter may well be what caused the blurriness. If you can, play around with it to sharpen those lights up a bit. :) If you ask me it looks nice as is, but if it's not what you were going for, the bloom filter is a likely culprit.

DrNewcenstein

Bloom is the glow around a light source (or its reflection when it bounces, as on her left arm). The blur in this looks to me from the Pixel Filter setting, which, from what little I've tinkered with it today, seems to cause the same blur that Poser's DOF setting does, which is what I'm seeing in this image.

DrowElfMorwen

Thank you guys, I actually figured it out last night: it was indeed the bloom filter causing all of my problems. Well, most. 12 hours into the new render, it still needs a bit more time, but it's basically perfect.