Non-directional/ambient environment for Iray?
RenderPretender
Posts: 1,041
Hello -
Is there such an animal as a non-directional/ambient environment for Iray that can be combined with other light rigs? I find myself having to use environments to try to bounce some light around in additon to a 3-light rig I use, but all the environments seem to be directional by nature. What's the best source of ambient light for Iray? I was thinking of trying iRadiance Light Probe set for its soft light presets, but it never seems to go on sale.
Post edited by RenderPretender on
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I'm sure there are multiple ways, but you could just make your own, assuming you've a paint app that can do 32 bit. Create a new image with a 2:1 ratio then make a gradient from midway up vertically and something neutral for midway down. I'd post a couple I made in HDR Studio, but don't have them on this system. You'll need to experiment with the gradient in any case.
Make sure to save as 32 bit such as HDR or EXR. This is going to get mapped onto the enviro sphere in Daz.
I don't know but if there is it's likely an artificial HRDI (no image just a grey-ish plane) with equal brightness throughout.
I just tested what Doc Acme suggested in Photoshop, and it worked well to create a simple ambient source. I'd say give that a try. :-)
I have GIMP. But I wonder if one could alter an existing HDRI to clone out the whitepoint rather than starting from scratch?
I don't have Gimp, so I'm not sure of the details. But cloning out the whitepoint might also work, if it will let you use the clone tool.
That said, if it's like Photoshop, you should be able to make an 8000x4000 px image at 300 ppi, 32 bit. Then use a gradient fill tool. Set the top of the fill tool to a light color that you want your ambient light to be (I used cream), and use the more neutral tone for the bottom half (I used a blue gray). Apply it, and you're done. (Granted, it doesn't look exactly like the other HDRIs that have a clear "ground" point, which I think is what Doc Acne meant by having something neutral halfway down, and the gradient above that).
Then just put it into the image slot of the Environment section of the Render pane. :-)
Thanks, I'll give it a try!
Good luck! :-)
Well, that did work. I had a bit of trouble trying to sort out how to get anything other than a grayish gradient out of GIMP, so I went with that. It's not altogether unpleasant, but it might get pretty boring. I'm using it with a 3-light mesh/spot rig that adds some nice shadows and dimension to skin. I still don't see why content creators don't seem to offer non-directional HDRis in various tones. I hate having to fiddle with the environment's directionality so that it doesn't compete with other lights in the scene.
Thanks for the help thus far!
I made another test case that's a sort of gradient "dusty rose", and that's a nice effect as well. The non-directional HDRI environments allow my mesh/parametric light rig to easily be controlled and do its thing without interference from a directionally dependent dome. Ambient light just bounces around uniformly.
Question, though: Is it best to use tone mapping or environment intensity to adjust environment brightness?
Glad you got that working. :-)
I think a lot of times HDRIs are used with the intent to get realistic directional lighting, so that's why we don't see the ambient ones as much. At least the ambient ones are fairly simple to make. The dusty rose one sounds like it could have a pretty look.
I did a quick experiment, and I think if you want to change the brightness of your HDRI only, then you'll want to use Environment Intensity and/or Environment Map. (To be honest, I haven't quite figured out the difference between the two), but if you want the background HDRI to look bright when on, you'll need to play with Environment Map, though they both effect howit looks).
If you want to brighten all the lights, then I'd use tone mapping. (Really useful, especially in indoor lighting).
All of the HDRIs can be rotated so that you can get your light bounced where you need. You can also make a big "Ghost Light" and put it overhead to get general lighting.
If you want diffuse somewhat directional or overhead light, what I've done sometimes is use sun/sky and change the sun size to 32 or even larger, then tweak the sun intensity.
For example, a reasonably decent moonlit scene can be had by reducing environment strength to, oh, .05 or .01, increasing 'sun' size to 32 or 64, then increase sun intensity to 50 or so. Maybe also adjust sun color a little toward blue.
Bam.
Works a lot better than you might expect!
Wow - that's a great tip - thanks!
For indoor scenes, one trick I've used is..
You definitely don't want it to be too strong as it can wash out shadows and contrast and make the scene unnatural, but it works okay for quickly adding some pseudo-ambient light indoors.