Calling all 3ds max and Mental Ray masters..help!

[whoodt]

Hi people,

 

I'm not a professional 3ds Max user, just hoping to get better. It'd be great if anyone can give me some pointers!

 

The attached image is done in max7.5 and mr 3.4. It's not meant to look REALLY real but more stylised. (I'd like to eventually learn how to make it real). Its' not finished but I wanted to get an idea of the lighting in the scene before I keep going. What turned out here is mind boggling to me.

 

THis model is not in right scale. It's actually reall small. I f'd up. THe dining table is like 1.4 inches long.

 

I'm struggling for ages to get the scene lit evenly. But it just wont. Let me briefly run through this structure:

 

All lights are either self illuminated objects(the chandelier, the white dots in the living room on left and top right bedroom (output map on self illumination slot with output =20) or mr area spots most have a multiplier value between 2-5 and I can hardly see the light.

 

Whereever you can see through around the outside of the structure(windows), there is MR Glass, except for the very very left on the image, supposed to be a walk out.

 

I had some multilayered material in there but it gave me some serious massive black blobs in the render but I changed out the material, upgrade to SP1 and MR 3.4, so far theyre gone.

 

Rendering with mr. Caustics off. GI on. (800samples of 1 inch radius)

Trace depth 10 max, 6 each for refl and refr.

Light properties, averge photo 250000, multiplier 1.8, and decay 2

FG on, 300 samples. Trace depth 15, 10 each for refl and refr. Fall off starts at 5 ends at 10. (Like said I screwed up the scale and everything is tiny in inches.

 

Here are all my questions. (I have a ton, hope y'all dont mind)

 

1) The living room on the left- there are only 3 mr area spots in it but for some reason I cant get the hot spots to really show up on the floor (which has a raytraced reflection) It's like as if the light isnt there or strong enough.(you can kinda see a light patch of blue near the far wall) If I crank up the multiplier, things start to really look like they glow, especially the red stairs and shelves

 

2) same with the dining room. I got 6 spotlightss coming down on the dining table and I can barely see It. THe spotlights are just under each of the red "cones" in the chandelier (The white spheres at the bottom of the "cones" are self illuminating. For some reason, It doesnt look like the lights are working at all and ironically, the top red cone is illuminated when there is no light shining on it!? And the drop ceiling at the very top has this light leak (almost looked like I wanted it there on purpose) but I dont know where it came from. The floor here is a darker reflective raytraced floor with a falloff map in Refection slot (just like any floor here)

 

3) The kitchen (under the top right bedroom) has 2 spot lights above the "sink" And I can barely see the sink, but there is an orangish area happening on the wall, where it came from, I dont know.

 

4) If you look at the mezzanine level, where the stairs lead, the glass window on that level got these white dots on them. I dont know how they got there.

 

5) I find it hard to predict what object colors look like, if I use a normal red in the stairs and stuff, they really end up glowing and bleeding all over the place. THe floor colors are very very dark, almost black, but here, you can tell they're blue and grey.

 

I got a lot more q's, but these are my biggest ones. If you can help, MANY THANKS,

 

Hubert

[pixelperfectg]

Scale is ultra-important. So the first thing I'd do is convert the scene to feet/inches or metric, etc...whatever you're comfortable with. Then uniformly scale the scene up to a normal scale. But for best results, always model items as close as possible to scale.

 

Once the scene is scaled properly, I'd turn off all the glowing items you have. And turn off GI. Setup the actual lights first, ensuring to use proper attenuation/falloff (or photometric lights).

 

Once you have the lights setup properly, then turn on GI only. In case you didn't know, the glowing objects aren't contributing to your GI calculation because they don't emit actual photons. They only contribute during the FG calculation. So focus on GI first. I'd recommend not entering a custom sampling radius for the photons (same for FG) unless you know how to calculate the proper size.

 

Next thing, I'd work in a linear space. Meaning you should change the 3dsmax default gamma setting to 2.2 instead of the default 1.0. You'll need to do some contrast/color adjusting in post, but you'll find it much easier to get an even light distribution without a ton of color bleeding. I discovered working in a linear workflow from the Vray folks and it's been great. I have a thread at vizdepot.com where we've discussed this topic and I supplied links to the original information:

http://www.vizdepot.com/forums/showthread.php?t=3465&highlight=linear

 

Ok, now that you have that setup... turn on FG and those glowing objects and adjust as needed.

 

General tips:

In the manual it states "MR does not support multi/sub-object materials"...sometimes it works just fine...sometimes it don't....just keep that in the back of your mind whenever you see spots or other weird things.

 

Color bleeding can be controled by:

(a) use photon(base) map.

(b) never use highly saturated colors like R 255, G 0, B 0

© work in linear workspace.

 

Scale.

 

Scale.

 

(did I mention scale?)

 

Other useful threads:

MR FAQ:

http://forums.cgsociety.org/showthread.php?t=303284

Shader palooza:

http://forums.cgsociety.org/showthread.php?t=104578

Sample scenes:

http://jeffpatton.net/Max6/index.html

http://jeffpatton.net/Max7/index.html

 

scale.

 

If you have questions about anything I've mentioned. Be sure to run some thread searches here, at vizdepot.com or cgtalk.com. You'll probably find the needed info and not have to wait on a response.

And finally....SCALE.

[whoodt]

Awesome...and hopefully the lights will start to show. Thanks!! I'll work on it and post the progress.

[J.R.]

If you still cant get rid of these light leeks at the ceiling, try turning finalgather falloff completely off when using GI. 10 inches radius is too small anyway for collecting FG-points IMO. I would rather use a radius big enough to capture the illumination of one room.

[whoodt]

Thanks. Changing the scale helps big time. The image looks better now and the lights are working as expected. I'm rendering a second time with a higher Global Energy for GI so that the spot lights bounce off the floor and hit the ceilings and walls. I find it hard to tell when rendering with FG off, everything seems bright enough, and then you turn on FG, bam, it's all dark again.

 

One thing I'd like to ask anyone, is that why do "bubbles" appear on glass when you have rays going through more than 1 pane of glass? It's in my original render as well but I cant seem to get rid of it. Any help is appreciated. Cheers