HDR GI

[pobr03]

I'm having difficulty getting my HDR maps to work as Skylight or a Background. It just comes out as black regardless of what I do and I don't seem to be able to get any light from them at all.
I'm setting the Skylight and the Background to a bitmap of my HDRI as a spherical environment. No matter what I seem to change it will not appear in the rendering.
I really don't know what I'm doing wrong.
Any help would be greatly appreciated.
Thanks.

[dalomar_cg]

Re: HDR GI

Chances are, if you haven't changed too many of the default settings, that the physical camera is enabled. Having the physical camera enabled will change how the lighting of the scene is interpreted. Right now your HDR is underexposed and thats why it is coming out black. Increase the multiplier within the texture editor to something like 50 and see what happens. Increase it until it shows up and is in the proper exposure that you desire.

[pobr03]

Re: HDR GI

Thanks dalomar.
I can now see the HDRI. The only difference is that I had to turn it up to about 7000 to get the desired atmosphere! Does this sound normal?
Cheers.

[dalomar_cg]

Re: HDR GI

It doesn't surprise me. The thing is that by default the physical camera is exposed for the Sun, which is about the brightest light you'll every use (385 brighter than white if you were to not use exposure). That means that your going to have to increase the hdri allot to counteract that drastic of an exposure. The hdri itself also comes into play as well because of how bright the actual image is. Some are very bright and have quite a bit of range, and others are not to much brighter than standard images.

[pobr03]

Re: HDR GI

In your experience (for architectural exteriors) do you get better results using the standard sky or and HDRI map?

[dalomar_cg]

Re: HDR GI

It depends, as I have used both. It usually depends mostly on the desired result of reflections (i.e. reflections of the sky in the windows of an office building, or on water or something). If you really need those reflections to show the details of the hdr your using, then you should definitely have it in the scene. But if its not that important you can simply render with the sky and either leave it, or comp the hdr in via photoshop and alpha channels. Also if the HDR has some specific colors that you really want to influence the render then I would use the HDR.

[pobr03]

Re: HDR GI

Thanks dalomar.
Great help as usual.