View Full Version : glossiness maps in mental ray don't work

03 March 2012, 03:15 PM
As in the subject...
If i put a glossiness bitmap map in mental ray this will not work.
With a procedural texture it's OK.
What Am I missing?

03 March 2012, 07:06 PM
Are you using Max, Maya, or Softimage perhaps? By "glossiness" do you mean reflections? Are you using the mia_material_x (arch/design material in Max, I think)?

03 March 2012, 07:41 PM
Sorry , I'm using Mia Material X in maya 2012 + the glossiness values in the reflection tab

03 March 2012, 09:49 AM
in your file texture node you need to make sure you have 'Alpha is luminance' checked on as the connection from the file texture to the glossiness slot is via the Out Alpha.



03 March 2012, 05:01 PM
Thank you very much!

06 June 2012, 03:17 AM
i have got a question in the same vein: whenever i plug a texture file into the glossiness, the glossiness value gets stuck at 1 (yellow background) and hence the glossy samples get frozen at zero. how do i get that glossiness value below 1 so i can access the glossy samples!??

thx a lot!


06 June 2012, 03:33 AM
take for example this copper material:

there's a specular map plugged into the glossiness at a value of zero hence you can change the glossy samples. i can't for my life recreate that scenario. also, "alpha is luminance" is not ticked.

similar this bathroom tile material here:
a specular map is plugged into the reflectivity slot at a value of 0 (which, again, is impossible for me to recreate as whenever i plug anything into reflectivity/glossiness it always goes to an unchangeable value of 1) and "alpha is luminance" is also not ticked. this confuses me.

what i want to achieve is plugging in a simple specular map which defines reflective/non reflective parts...

thx loads for any help!!!


06 June 2012, 03:51 AM
I think you're going about this the wrong way, perhaps? You should be plugging the glossiness map into the reflectivity channel itself, and not into the glossiness channel. Alternatively, the bump channel if you need greater control over the strength. It's not like specularity, which is a fake reflection method. I've never found any need to plug a texture into the glossiness channel thus far.

06 June 2012, 04:27 AM
quote from different thread i just came across: You probably want to put your texture map that regulates reflectivity in the glossiness slot instead. The material was kind of designed that way because that's what happens in real life. Materials aren't less or more reflective, they are less or more glossy. The more glossy they are, the less reflective they look because glossiness reduces intensity.

i am texturing a toolbox which is painted metal and I want to enhance the parts where the chipped off paint comes through, usually easily done with a glossiness/reflection/specular map, so i just wonder if thats possible. looking at the two material examples i posted links to earlier it obviously is...

06 June 2012, 01:07 PM
That's right, varying the glossiness (or roughness of the surface) is a much more realistic way of making a material. If it's less reflective it's usually when there are other materials like dirt on top of it. I'd use two material setups and use a mask to blend the two to get correct results.

07 July 2012, 03:39 PM
I'm not sure if this covers exactly what you mean.. but you can get round the glossy samples being greyed out when mapping a texture using one of djx's great scripts.

Works in 2013 too...


07 July 2012, 08:43 AM
hello! what i ended up doing was actually mapping the R channel of the texture's color out into the glossiness through the connection editor. works a charm!

07 July 2012, 06:41 AM
That is only accurate if the map is black and white. If it's coloured then it's possible that it's not getting all the detail out of it. In that case the best would be to use "alpha is luminance" and connect the outAlpha value to glossiness, but once again that's only if you are using a coloured map and you want to use the luminance values of it to drive the gloss.

07 July 2012, 09:20 AM
Has anyone quantified the results by using the glossiness channel in this way? I shall test it tomorrow and see if the results bear more scrutiny.

It's not the same as a specular map. Although we want it to be...

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