Mental Ray / SunLight Problem

[Ninja]

Using a sunlight with MR is giving me a completely black render...I have enabled Final Gather, and flagged the light to use MR,,,but nothing

 

anyone any ideas >?

 

thanks in advance

[Fran]

Hi Martin,

 

What kind of sunlight are you using? Mental ray doesn't support IES lights. Is this an interior or exterior space? Does the mental ray error log open when you render? Is it enabled?

[jucaro]

Yes, as what Fran said, MR doesnt support IES sunlight. Use direct spotlight instead if you want to simulate sunlight. For the past few weeks, i too was struggling on how to light both interior and exterior scenes using MR and using just one light source.

 

IMHO, i would still stick to Vray.(at least for the time being until i get to understand MR.)

 

MR produces more believable results than Vray. But in terms of speed to deadline schedules, VRay sets the pace.

 

As of now, I'm still experimenting how to make MR render as fast and as optimized.

[Ninja]

Thanks guys for the feedback.

 

Im attempting to render an outdoor scene with a single light (very important I used GI)

 

The MAX6 on-line reference does state that a sun light will work with MR BUT to enable final gaterhing to avoid very dark results...and yes, I do get errors and warnings in the MR dialogue. The "sun" light has MR dialogue in the modify panel....so surely it must be supported by the MR render ?

 

...any suggestions for an efficient out door lighting solution including GI (with MR) guys ?

 

thanks

[xgarcia]

Just FYI:

There is a sticky'd thread over at CGtalk.com about Mental Ray shaders. Not sure how much applies to arch. viz. but some time saving tweaks have been discussed. Hope that helps.

[jucaro]

You'd have to use a lot of GI samples if you want to light a scene with just GI alone, and only fewer if you want to use FG at the cost of longer rendering times.

 

If you want to light an exterior scene with HDRI, GI has no use. Instead, use FG+skylight or a Dome mapped with an HDRI map, but still you'd have to use FG (basic HDRI scene setup still applies).

 

And oh, BTW, the MR scene in the MAX6 CD is useless for learning if at all. The tutorial and Help was tinee bit only for grounding and basics

[Ninja]

so rule of thumb....avoid MR for exterior scenes ?

 

thats ashame

[jucaro]

NO. Rule of thumb is...if you have a deadline, stick to what you are familiar with.

 

IMHO, MR is really OK. exterior scenes are quite easy to set up than interior ones. But i'm still biased to the speed that Vray offers and the results that I want. Vray is more predictable in terms of output and speed.

 

MR renderings look great though, but the myriad of settings it has can leave me baffled and frantic on how to optimize the settings.

 

[ November 29, 2003, 03:59 PM: Message edited by: jucaro ]

[siliconbauhaus]

actually mr does support IES files.....from what I've found anyways

[abicalho]

IES Files are different from IES Sun and Sky.

 

Alexander

[Ninja]

thanks for all the feedback....going off on a tangent Im looking at using some HDRI files with GI / Radiosity solutions...I get how they can be used for great r/trace reflection work....but can anyine offer me some advice as to going about using them for a radiance map...once again the Max literature is really lacking

 

cheers

[Christopher Nichols]

As will all rendering engines... you can't can expect them to simply work the exact same way as eachother. It usually takes a lot of practice and not a simple button click. Different rendering engines require different rigs. MentalRay would be similar to the raytracing power of Vray or Brazil, with the complexity of Renderman. The complexity issue is the most difficult one to deal with. Once you learn to program in MI (the programming language of mentalray), you will find yourself loving it. While Discreet has given you a lot of really great tools to help you, it is a little more difficult when deal with it "out of the box."

 

Don't think of first step setbacks as failures. Keep learning... it may take a lot longer then most other rendering engines... but it will be worth it.

 

If you become a good MI shader writer... give me a call...