Lighting & MR Advice Exchange

#30

i have been doing some reading on lighting in max and have found a really usefull trick to create fake shadows…

As you all probably know, most of the computation in a render is processing shadows

To cut down rendering times you can fake shadows by setting a light to a -1 multiplier and turning off cast shadows… This can be used to darken corners of rooms etc…

ie if you were to place an omni light with the above settings in a well lit room in the corner … the corner will then become darker as if something is casting a shadow…

This can work well for photorealism but a good grasp of where shadows will be is needed…

hope someone finds this information usefull

kind regards

nebille

#31

for the direct light problem -

couldntyou merely create a spot a long way away but cut down on rendertime by using attenuation controls? then you should get the best of both worlds.

#32

Folical9, what do the splines do?? i couldn’t find anywere were they were used so i had to ask :slight_smile:

thnx

#33

Abbegon, the splines are paths the glowing spheres will follow in the animation. I have the omni’s linked to the spheres and the spheres follow the path. It just took too long to render on my PC but I have motion blur setup as well if you enable it in the render rollout.

#34

ah ok… :slight_smile: thnx

#35

Hello. New Max 6 user here. Thought I’d post my first attempts with GI and FG. Just a simple room with default materials. I was going for smooth lighting, no artifacts, and a fast render. This scene renders (on a P4 2.66GHz system) at 2 min 22 sec, with about another minute or less for photon generation and FG processing. Add a few more minutes if turning up AA sampling for a final render (which I didn’t do).

The scene contains 1 MR Area Omni (10x10 area sampling), with inverse-squared falloff.

As stated previously, exposure control is key to getting good lighting, as well as paying attention to scale. Mental Ray is pretty sweet. Definitely worth taking the time to learn and tweak for the best results. Here’s the scene if anyone’s interested:

GI/FG testing scene for Max 6

#36

As far as night time lighting with mr, i got great results with the lume night lens effect. This scene is set up with two standard (kind of dark purpleish) omni lights, one is set up as a the main light, the other is just to fill in the shadows a bit. The shadows are raytraced. All the trees and bushes are from the aec follige.

#37

47Gut: Could you post your scene? Or another simple scene like that?.

#38

another topic with MR. its only an idea from me. i dont like mentalray at all. i used some other third party renderers and when im comparing… . the main problem i see in MR is its speed. only an idea:shrug:.

#39

anyone have something about this subject?

as i see there are 3 lights:

  • standard
  • mental ray
  • photometric

i did a simple test and did not noticed any change between standard and mental ray lights. unfortunately, i still do not have a good place to post the images, altought there aint much thing.

all tree lights, with final gathering, took 5 minutes and a half. visually the difference is only between photometric and the other two, altought an “area shadow effect” i could only get with mental ray light with ray traced shadows. :shrug:

anyone have any experience with different light types with mental ray?

eks

#40

maby another problem. mentalray in some cases like this is limited :D. lighting in mentalray seems too weak to me.

#41

i strongly disagree with arona in one point, but agree in another.

i do think lighting and shadows makes mental ray stand out. but it definitly is slow.

so, any one have tips about mental ray optimization? to reduce it´s render time without too much loss of quality?

eks

#42

mental ray can be as fast as other solutions
only the room for error is a lot smaller…
once you know the ‘tricks’ it is possible to have acceptable rendertimes
there is no golden solution, just try untill you find your workflow that suits you
and look around and search in forums like this how other people do it…

and if you still don’t like… pls stop complaining and don’t use it :wink:

#43

Even though the direct lighting problem was posted a while ago, maybe other can benifit from this info.
First of let me clear the issue that the sun does NOT casts soft shadows. It cast hard defined shadows, that being because all the light rays from the sun are parallel, which is what a direct light is. If you have a pole and follow the shadow during the day it does apper to fall off or become lighter the further you get away from the pole. But the fall off is do to the light scattering in the sky and reflecting back down to the ground and lighting the surface. So to make the soft shadows in MR you would have to enable GI and or FG and then the shadows will look more realistic and have soft shadows like the picture Herbert West posted.

I am currently experimenting alot with mental ray to accuritly light a House that I am modeling and one of my biggest challenges is to get the interior lit correctly with only the daylight system. The interior is always to dark, not enough light is bounced. If anyone has any tips, please post them.

I think this is a very useful thread if as many people posted as in the Photon shading thread by Jeff Patton, and I hope to help as I figure out more settings and tweaks

#44

hay jeff i rendered that scene that you posted it work great but theres a small prob with the light in the courners of the room they seem the give off funny shadows like patches that move strange when the balls move around?

#45

You’ll have to increase the final gather and/or GI settings to get rid of those artifacts. Naturally, that will increase the render times too though.

#46

ah ok lol i wont try it, that animation took long as it is thx for the info!!

#47

Vulcan, have a look at the shadow/light the sun casts from your window onto the floor of a room : it will be very hard near the window, the further it falls, the less sharp it will be.
So there is allways a small ‘area shadow’ even from the sun. It might be very small, but it is there for sure :wise: really, just have a look yourself…
so even for sun you might not wanna use a direct light.

secondly using a daylight system for interiors might not be such a good idea : the skylight is almost useless for interiors, imhexp. it is better to use area omnis (the size of the window) outside just infront of each window instead
this way you will have less probs getting the light inside brighter…

#48

Vulcan, what about placing some bounce lights around the room (area lights that exclude the thing they’re bouncing from, like a floor bounce light excludes the floor) with very low multipliers, and color of what they’re bouncing off of (like a bounce light from a blue table casts a blue bounce light).

Or is that cheating for what you’re trying?

#49

This is a great thread :slight_smile:

Can anyone tell me where the AA setting is?