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View Full Version : Similar material to 'VRay Mtl' in Mental Ray?


IestynRoberts
04-10-2011, 12:04 PM
Hello.

Does anyone know if there's a similar material in Mental Ray to the 'VRay Material' that comes with VRay - the standard one that's just simply called 'VRay Mtl' in the Hypershade?

Thanks.

LinchpinZA
04-10-2011, 12:46 PM
Yes,
The mia_material_x.
In my opinion the mia is more robust than the vraymtl. It has better brdf reflection control where the user can input custom brdf curves for fresnel reflections instead of just using IOR. It can also be used in conjunction with the mia_env_blur node in certain situations which gives you glossy reflections for free with no noise. It has built in options for ambient occlusion which obeys color bleed and only appears in shadowed areas or areas of indirect light, where ambient occlusion is supposed to be.

Here is the documentation for it http://www.mentalimages.com/fileadmin/user_upload/PDF/arch_and_design.pdf

IestynRoberts
04-10-2011, 03:15 PM
Hey Christopher. Fantastic! Thank you very much - that's perfect for what I need. Cheers also for the documentation link. Great stuff!

Another quick question, I'm trying to follow this tutorial on creating a nice render, and he's using VRay. As the light, he's using VRayLightRectangular - does anyone know if there's (again) and equivalent without getting VRay?

Thanks.

LinchpinZA
04-10-2011, 03:25 PM
Yes,

Create a maya area light. Make sure under intensity you set falloff to quadratic. Vray lights have by default inverse square/ quadratic falloff, mentalray and maya lights DONT!. All lights in the real world have quadratic falloff and obey the inverse square law. So make sure that is enabled.
Under the shadow rollout tick use raytrace shadows, under the mentalray rollout tick 'use light shape' set high samples to 16 for preview renders, set it to 64 for final renders.

I insist you learn linear workflow in maya as it will make lighting/rendering a lot easier, whether you use mentalray or V-Ray, linear workflow is essential and will avoid many issues. Refer to this post (http://forums.cgsociety.org/showpost.php?p=6940026&postcount=3) of mine about it .

*Edit*
You might notice in the vray tut the guy will use the U and V scale to change the size of the light and will say that you mustnt use the scene scaling to adjust the size of it. Well in mentalray you simply scale the light using the scale tool, there arent any u and v scale things to change.

IestynRoberts
04-10-2011, 03:44 PM
Hey there. Again, fantastic Chris, thanks for the info. It's very appreciated.

Yeah the guy in the tutorial did use the U&V to scale, that's good to know about the MR lights not working the same way.

The liner workflow sounds very interesting. I shall give it a read and see what's it about. I'm really not very familiar with Mental Ray - so this will be a good step forward. Thanks again.

LinchpinZA
04-10-2011, 03:58 PM
Cool no problem, always glad I can help people starting out.

I have used mentalray and V-Ray extensively. Mentalray can do just about everything V-Ray can do. The main advantages V-Ray has over mental ray is a slightly easier/quicker workflow and better indirect illumination sollutions aswell as a quicker passes setup. In my opinion mentalray has a stronger shader system but each renderer is pretty good at different things.

Most of the time I stick with mentalray for bigger jobs as I have more control over optimizing glossy reflections and ray switching on a per shader level. I use V-Ray when I have to assemble a shot really quickly and when I dont have to render things on tons of different layers.

A previous thing I didnt mention, you will notice with your lights set to quadratic falloff you have to enter quite high values, dont be scared by this, its ok. In high dynamic range photoreal setups where things are at physical scale 1 maya unit = 1 cm I often have lights with intensities in the millions.

But yeah before you learn anything more with mentalray, I suggest you start working in linear colorspace. It's probably the most important topic when learning rendering and lighting. And yet it's so ironic that it's the most undocumented topic.

*Edit*

Here are some blogs that are worth checking out.

http://www.djx.com.au/blog (http://www.djx.com.au/blog/)/ DJX's blog was primarily a maya/mentalray blog, he's recently switched to vray so a lot more recent posts are about vray, but theres still a worth of knowledge on there relating to mentalray from previous posts..

http://3dlight.blogspot.com/ Same thing goes for 3Dlight's blog, a lot of his recent stuff is vray related, but theres about 3 years worth of posts mentalray related. If you start from his earliest post and work your way up, you will learn a lot.

http://mentalraytips.blogspot.com/
Master Zap, is the mentalray guru, also a ton of invaluble information here. All of his posts are for 3DsMax, but you can apply the same settings to mentalray in Maya.

IestynRoberts
04-10-2011, 06:11 PM
Great! This is awesome of you man, thanks a lot for the links.

Yeah, when I switched to quadratic fall-off, I had to really pump up those values.

The linear way sounds pretty good to me. I'll start to play around with it this evening I think, and be sure to check out those blogs.

Thanks man.

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