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Old 05-18-2009, 08:57 AM   #1
llihneb
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Ben Hill
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mental ray bathroom scene trouble

Hi,

I haven't had much experience with Max or Mental Ray and I'm having some trouble getting the lighting to work in a simple bathroom scene.

Unfortunately, many of the objects are reflective white and chrome which probably doesn't help. I have tried adding various colored objects in a range of positions within the scene to create reflections but that hasn't worked.

The main problem has been getting the shower screen and fittings to produce dark and defined shadows to provide some contrast. I've been playing with photometric light, GI and FG settings for days now and finally decided to ask for some help. I'm using a daylight system with 2 x mr sky portals (window and doorway) and a ceiling photometric light. Adjustments to the photometric light don't seem to do anything.

If anyone with experience in this sort of thing could give give me some advice, that would be fantastic!

Cheers,
Ben.


Last edited by llihneb : 05-18-2009 at 09:31 AM.
 
Old 05-18-2009, 01:14 PM   #2
kanooshka
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Dan Konieczka
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There are many factors to getting a strong render using this technique.

One large piece is the intensity of the main light source, in this situation the sky. This create issues itself. The sky provides very uniform lighting both with color and intensity. Think of a cloudy day, essentially this is a sky lit environment with no sun as a main light. Cloudy days cast very uniform light, because of the same light intensity and color from the surface area of the sky.

This brings me to the next factor which is exposure. The sky lit interior can work when needed but requires exposure control to create contrast. This image is a good example of exposure and contrast:
http://farm3.static.flickr.com/2054..._553ddeb0d5.jpg
As you can see, through the window's all you can see is white, near the windows is the brightest cast light and then on the diffuse lighting falls off to darker tones as it becomes more indirect.

Another factor you may want to take into consideration is light location. The window to the side works wonderfully, it should provide shaping to the objects in the scene. However, you mentioned there is also a doorway in the scene. Where's the location of the doorway? One place you will not want it is behind the camera. If you place the door behind the camera and it possesses the same intensity and color as the window all of the contrast the window creates would be lost. My suggestion would be to start with one light source, the window, and get that looking right with good contrast. If you need to add another light direction afterwards, by all means add another.

Finally you mentioned almost your entire scene is reflective materials. If this is the case then the only reflections will be reflections of reflective objects. To get nice looking reflections you may want to add some more diffuse objects to your scene. This will also help you nail down your lighting. As another method you could also temporarily add a nice diffuse shader to everything in your scene to start with. This will help you obtain the best starting point for lighting.



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Old 05-18-2009, 01:33 PM   #3
llihneb
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Ben Hill
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kanooshka,

thanks for the advice. The exposure (daylight, indoor) issue has been resolved but I'm still having trouble with reflections on the chrome. I've done as you've suggested and culled the door for now.

Thanks for the pointers
 
Old 05-18-2009, 01:33 PM   #4
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