HDR lighting problem

[Anonymous]

I am trying to learn how to use HDR images for Image based lighting, but I ran into a problem that I can't solve.

I used this tutorial http://www.youtube.com/watch?v=vctH9LZ-h_k and when I use a mr physical sky the scene is lit correctly (see image 1).

But when I use a bitmap with an hdr image it looks as though the light source is located at some negative z location, because the top of the torus knot and teapot are lit, but the plane is no longer lit. And the teapot seems to have a completely different material, it is no longer matte red, but almost chrome-like (see image 2). Moving the plane down on the z-axis didn't make a difference.

If I then add an extra light, the plane and teapot are lit again.

What am I doing wrong? I tried changing the placement of the image in the bitmap, I also tried connecting the hdr bitmap as background map to the mr sky map, or connecting the hdr bitmp as sky color to the skylight, but none of that solved my problem.

Thanks!

[Anonymous]

May be a silly question, but do you have FG enabled?

[Anonymous]

Yep 🙂

But I'm using the Skylight mode 'Skylight illumination from IBL'. I just now tried the 'Skylight illumination fom FG'  but that didn't make a difference.

I attached the scene, so you can have a look.

The hdr I'm using is this one:

http://www.hdri-hub.com/hdrishop/freesamples/freehdri/item/76-hdr-sky-cloudy

[Anonymous · Accepted solution]

When using IBL do not use mr exposure (or any exposure). Also, for background use that jpg that is provided, and for lighting use that blured hdr. Look here:

http://i.imgur.com/Co9JYKi.jpg

[PROH]

Hi. There's an interesting thread about IBL and HDRI here: http://forums.cgarchitect.com/75415-mr-photons-ibl-fg-nothing-thime-better.html

[Anonymous]

Thanks!

It looks like disabling mr exposure was the key. With the other changes I noticed different light intensities (using the hdr as environment and for lighting resulted in a brighter render than using the jpg as environment and the blurry hdr for lighting). I'll play around a bit more with those alternatives.