CGTalk - Mental Ray: Questions of it's Power

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danylyon

10-24-2002, 01:55 PM

I'm about to buy Maya 4.5.. one of the reasons beiing MRay.

The only thing I'm wondering.

1. How does it deal with Displacement Maps? Is it as slow as the default Render or does it deal them the same way as Renderman?

2. I'll need to render a HiRes Scene (3000x6000) with lots of Maps (600MB at least).. lots of Polygons and.. to add to the complexity Displacement Maps. How does MRay deal with such a scene? Cos the Maya Render won't even start rendering.

3. Can this be done with the Beta?

Edit: I'm running on an Athlon 1800 with 1GB of RAM.

MCronin

10-24-2002, 02:09 PM

I'm probably not the right guy to answer this because I don't use MR but here goes.

1. MR is supposed to support microtriangle and subpixel displacements similarly to PRMan, but how fast it is, and whether or not it's implemented and working in Maya I have no idea.

2. MR is supposed to do memory mapped pyramid textures, which I guess is Mental Images way of saying MR will do mip mapped textures. This means the textures will have an LOD of sorts, and only pieces of the textures will be loaded into memory as required during rendering. In other production renderers usually a special mip mapped texture format is used for this, but I'm not sure if MR requires a special texture format, if it's a switch you need to hit, or if MR will just do it automaticly. Again, I'm not sure if this has been implemented into MR for Maya.

3.My guess is probably not. I just took a quick look at the beta and it doesn't seem to support even NURBs or subdivision surfaces yet, but like I said I don't really use it so I could be way off.

JupiterSunset

10-24-2002, 05:18 PM

SubD´s a no but NURBS it does, of course!

Displacement:

I did a simple NURBS plane in Maya4.0, with a disp. map 2048X2048 and enabled Feature Displacement with pretty high values:
Initial Sample Rate:90
Extra Sample Rate:80 or sth.
On a Dell dual xeon 2.4ghz/4gb ram it took some 40mins for a 1280x1024 intermediateQuality preview/ glass material/ reflections and refractions involved.
But result was crap. too few polys.
So I tried to double the
Initial Sample Rate:180
Extra Sample Rate: 160
it´s like 40 hrs. ago and still prepares to render.

Same scenario with Maya4.5 and MrayforMaya1.5beta:

disabled the Feature Disp. in order for the micro/subpixel-thing to work, and it took like 2-3 minutes for a 1280x1024 production-quality render that looked fabulous. only this time it did that on a 1533mhz oldschool-athlon/1.2gig ram.

Though I had few scenes where MayaRenderer was faster than Mray, most scenarios will be the other way round.

And on top to decsent raytraycing and usable disp. mapping, you also get the global illum/final gathering/caustics stuff (love it) and hdri.

Hope they integrate it even more, like subD´s and volume_fluids and stuff.

Maybe I´m a little too enthusiastic right now, but it´s cool to be able to start the renders that maya always refused to do.
think your scene will render.

Of course, these are only my experiences, and I´m no masterchief-pro or sth., so don´t sue me if it doesn´t work out for you this way.

danke/over

danylyon

10-24-2002, 06:04 PM

Sounds great. Thank you for your answers.

BTW.. I just got an EMail from my Reseller, which told me that the final Mental Ray for Maya will be available by the end of december (through a download).

JupiterSunset

10-24-2002, 06:40 PM

welcome, but sorry, I got one number wrong.
the displacement scene took 7mins. instead of 2-3mins.
but then again, with a glass object, refl./refr. set to 10/10 and production aa, this is still pretty cool. and: no triangles visible! all smooth!

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