View Full Version : Weird Render Issue

08 August 2011, 09:41 PM
Hi guys

Having a bit of a problem here, I am using mental ray and mia_material shaders mainly for rendering out a car model I made.

The problem I am having as you can hopefully see below is that the chrome materials are not rendering correctly. The two bars in the centre of the engine and the screws are using the same chrome material, yet for some reason, the one on the right renders white, instead of the way it should and does on the left hand side. I have tried several different render options but still get the same result.

Hope one of you guys can help


08 August 2011, 03:29 AM
check the face normals of the object, it could be inverted.

08 August 2011, 09:51 AM
thanks will do, just seems a bit weird for that to be the case since it is a duplication of the object on the left of it.

any other suggestions?

08 August 2011, 10:36 AM
If you duplicated it and scaled it negative then the normals will be inverted.

Have you also checked that the chrome material is actually asigned to that part, perhaps its got disconnected some where along the way and the default lambert shader is being used...which shows as bright white.

08 August 2011, 01:55 PM
ok thanks guys, I am not completely sure if this is correct but I have displayed the normals on both objects and they seem to be facing the right direction. Im not sure wether this is because the objects are actually subdivided, and maybe I should convert to poly, maybe? Anyway here is the image showing normals.


I did also make sure he chrome texture was connected :)

08 August 2011, 01:48 AM
Yup, that is weird, is there any history on the right object? A negative scale value? How did you duplicate the object? did you group it then duplicate and negative scaled the group?

08 August 2011, 08:35 AM
Not sure what is happening but what I would do is export just that part to a new empty scene, add a new shader, say a blinn or lambert, change the colour to green (or blue / whatever) and render a still to see if renders correctly.

Do a delete history and optimise the scene. Save it.

Import that scene back into the car scene and replace the new temporary shader with the mia_material chrome one and ......
....fingers crossed..... should render... as expected.

Unless there is something really strange going.

Bit drastic but it might solve it.


08 August 2011, 09:55 AM
thanks for the ideas guys, basically did what was suggested, deleted history, re-duplicated and converted to polys rather than Sub-D's and its now worked. Not sure exactly which solved the problem but its now rendering out perfect

Thanks again

08 August 2011, 03:26 AM
Its also possible somehow opposite got checked on

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