Mental Ray - Render Troubleshooting


Maybe this will help:


so basically i cant scale anything to zero??
how would i fix this problem?


I would assume that if something is scaled to zero it’s invisible and if that’s the case then why wouldn’t you just delete it from the scene instead of scaling it to zero?

In all the years I’ve used mental ray I’ve never ran across this error code, so I’m afraid I can’t offer any first hand advice. The link I provided above is the only thing I could find on it. If you’re on subscription then you could try the new help feature on it and/or contact your reseller to see if they can get an official answer to this issue.


Thank you Master Patton

I found the the object in question. its a building that scales up from flat for the animation I am doing. a college modeled it and likes grouping things. so I un-grouped it and made it into one poly object and somewhere down the line the transforms went all out weird…

ok, that problem solved, but now I need to somehow get the renders down from 13 mins a frame :frowning:

would anyone be willing to take a look at the scene and help me out?


hello everybody,
i’m trying to render a simple, scene with mental ray the includes thinking particles R4 and nothing else, no lights, no FG, nothing, just for test.
the problem is mental ray take so long to render this scene, but scanline render it in seconds so is their any problem with combining mental ray with TP R4 or what??
Please i need help.


Scratch that I found the reason.


did u find it, could u tell us please maybe there is a solution


Sorry I was asking about a completely different issue.

Although out of curiosity are you using object motion blur?


Hi guys - I assigned a generic Arch and Design material and put a cellular map in the bump. The only problem is that I edited the color map to be a plateau-like curve, but this has absolutely zero impact in the rendering. It renders identical with the Enable Color Map checked or unchecked. Do i need to wrap the cellular map in another map of some kind?



If you are using motionblur with particles, it will long to take rendering in mentalray. To solve this, you need to cache the motion of particles and render again with motionblur. It will be fast as regular.


Hi all
I’m rendering a car against a white background and using a switcher with white bg and a msr with transmat in the bg slot. pls see the img attached. Everything works fine but i get some harsh white reflection on the car body which i’m trying to get rid of.
I’m using three free point lights with visible to render on and a skylight with a highly blurred hdr. Could anybody pls figure out from where these white reflection is coming? If it is the white bg then it should not be there as i’m using hdr for reflections!
I’ve tried rendering to 16 and 32 bit output but the problem remains. Appreciate a quick help.



Posted this in the Studio Lighting thread but thought it may get a better response from in here:

Since I’ve started using Pmetric lighting I’m having trouble getting a white background due to the exposure controls. With standard lights I was using the background/environment switcher along with a matte/shadow/reflection map on a floor plane and this allowed me to control the scene colour much better. Now when I use it the background comes through as black even though the colour is set to white! I’m pretty sure this is due to my exposure settings but I don’t know what I’m doing wrong.

The settings I’m using to get the subject illuminated nicely are:

Shutter Speed: 1/4.5
f-stop: f/5.6
ISO: 800

I also have Gamma/LUT enabled set to 2.2.

Anybody have any advice on where I might be going wrong?


sandy_maith: Looks like the matte/shadow plane reflection to me. Did you try: select the shadow plane object and in the object properties make it invisible to reflections or using a raytype switcher?


TheAtheist, try the info here:


Thanks Jeff…it worked
simple is the way to go i guess…


Thanks Jeff, that’s a helpful link. Only downside is it makes my studio sweep show as flat white so doesn’t help with my current scene. Good to know for future projects though.


I have no clue what that means but ok.


Well i was just wondering which one of these works best…using a light probe in bg ref slot or just an hdr set to spherical env! Are there any differences . I found later one to be more in control but would like to know if there’s any other side to it.


I have an extruded curved spline behind my object which gives a nice soft studio look to the lighting when I apply a matte material to it, but when I tried using the method you linked to its as though the extruded curve is no longer in the scene, just shows as flat white. If I get chance I’ll post some example jpegs, I can’t show what I’m working on as it’s client work so I’ll have to put something else in the scene.

It may just be that I need to start the scene from scratch so I can set all relevant parameters to suit that technique.


Now i have another set of issues…i’m getting this white spill which i dont want on my car material…secondly, i get color bleed on the msr plane which again i dont want…theoretically i understand that color override raytype switcher can take care of this but what i dont seem to understand is how to use it in this situation. i used it on msr cam map slot…what i thought is that msr plane should use the info from the env switcher…but it didnt work…
for the car paint…i created another mental ray mat with color override raytype switcher on the surface slot and car paint on the eye ray slot so that i get only the car paint…on the ref slot i used the hdr which i’m using on the skylight …well…i tried many setups and seems i’m totally confused now…
how can i use raytype switcher in this situation!