Mental Ray problem - 3D Max

Gooner442

Hi all,

I'm giving Mental ray a go and experiencing what might be a problem, to have any light working I need to increase the multiplier for intensity to a very high amount like 50000!... seems a bit odd, is it trying to tell me something is wrong with my scene or is it normal to be using such high numbers with the intensity?

Ta

Martin

Piflik

I assume you have some kind of Exposure Control active. Open your Environment & Effects Window (8 on your Keyboard) and have a look...deactivate it or use photometric lightsources. They are meant to be used with Exposure Control active. You'll have to work in realistic size then, though.

r_fletch_r

So long as your scene is correctly scaled its not a problem. Whats happening is your fighting your exposure control. By default it Exposes to an EV of 15 which is tuned for a sunlit day. basically your Omni is having to produce the same energy as the sun.. drop the EV to 0 and you should get the results you want.

The problem is is that max's default lights are not physically correct. their setting has no real world bearing. at 1.0 they emit 1 candella which is a TINY amount of light. Id use photometric lights, they have realistic values/ falloffs, and give really nice area shadows and support IES profiles which rock Photometrics will give a far more realistic result than a standard max light which are shite :poly122:

Also if you want a nice render make sure your using gamma correction.

Gooner442

Thank you for the tips, I've only just had time to get back to it. Everything you've said works!.. it's so easy when you know how and the renders are much nicer.. I think I'll get myself a book/tutorial on this

Just one query with these photometric lights, I only have Target light, Free light and mr Sky Portal, are they all the lights you need, what if you want an area light?.. and it which circumstances are those lights used, for sun/lightbulb etc?

r_fletch_r

Its all built into the Photometric lights. To get area lights scroll down to 'Shape/Area Shadows' and set the shape to anything but point. Also it can be nice to make the light visible to the renderer. Photometics can be used for both Bulbs or a sun but if your doing exterior rendering check out the mental ray sun and sky system. it gives you a really nice lighting rig, with time of day effects, you can even tell it where in the world it is and what season and it will simulated the correct lighting. There are tutorials in the max tutorials which describe the workflow(its very easy)

Gooner442

I actually did those tutorials, so many tutorials I've forgotten.. but I'll go back, I remember it was pretty simple. thank you!