View Full Version : Mental Ray Interior Lighting - a perfect balance?

Rick Davidson
11 November 2006, 01:52 AM
Hey guys, just exploring the multiple options available in lighting using MR. I have an urgent job to put together and need a result very similar to:

Would I be right in thinking I just should use Final Gather & Image Based Lighting for a result like this? No need for caustics or global illumination? I need the renders to be fast but I don't want to skimp on quality. Looking at the above image it looks like a couple of area lights were thrown in for reflections? And shadows, just one directional light with raytraced shadows (plenty of shadow rays for soft edges?).

EDIT: Well I've tried HDRI and tho the render is pretty it absolutely kills render speed. Any tips there or better to ditch and go final gather only?

11 November 2006, 07:27 AM
So, FG and IBL is your choice
Get in mind that the power of MR is from shader, to archive that scene, shader play a super important part... the lightning is quite simple for setuping

11 November 2006, 04:38 PM
Do you want to use IBL for ambient lighting with an single color? You could just crank up your environment color to do that. For the light-reflections FG bounce cards might do it. They render faster than visible area lights.

Rick Davidson
11 November 2006, 10:27 PM
Bounce cards? Are they just basic poly planes? Yes really just want IBL for realistic reflections - figured an HDRI image was preferable to a block of white. At the moment I'm just using a single area light with soft shadows, FG, and an IBL map. Sound right?

11 November 2006, 10:40 PM
sounds right to me, with bounce cards I mean poly planes with a diffuse material that has a very high ambient or incadescence color value ( greater than 1)

11 November 2006, 01:43 AM
They didn't use IBL in that image. It looks to me like it's just a large white diffiuse box with one large area light hovering above the car and one FG diffuse bouce. The box that is being used for the lighting/reflections on the car has primary visibility turned off. The ground plane seen in the shot is most likely rendered in a different pass and composited behind the cars. Such a look could even be replicated with ambient occlusion, but unless it's going to be animated, the FG bounce will produce the results you want quicker. And as mentioned, use a bounce card to get the light reflection, not a visible area light, it will give you more control. Although I don't think I would make the incandessence higher than 1 on the bounce card, relying just on the area light to put out light will be sufficient. The most diffucult thing to replicate in that scene will probably be the shaders, but the mi car paint shader will probably make that simple enough.

Heres a shot I rendered using a similiar technique I just described only the light reflections are purely specular, which is why they're not sharp, and obviously the box I used for light/reflections still has primary visibility turned on

Rick Davidson
11 November 2006, 02:27 AM
Wow thats really nice! Could you tell me what sort / how many lights you used? Just one big area light? Use FG? GI? And just a flat plane for floor or did you box it? Very nice!

11 November 2006, 10:43 AM
Well you can use IBL if you want, actually just IBL and FG. no need for the area light for a scene like that.Here is something i did some time ago...IBL and FG..

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11 November 2006, 10:43 AM
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