Ok...
I've not been able to sort this one out.
I've sent screenshots to the OP which relate directly to their own personal files but in case anyone else is interested here is a generalisation of what I've found out.
The problem the OP identified stems from the .mtl file not not having any reference to the image maps used in the material. The .mtl file is exported from a 3rd party 3D app, for eg 3dsMax, along with the .obj file which contains the actual vertex data.
When the .obj file is opened in 3dsMax all is fine...materials show as expected but when opened in PS as a 3D layer PS does not have any reference to any image files used in the map slots....simply because the .mtl file does not contain any reference.
Ironically, exporting a 3D layer FROM PS to an .obj file DOES add in the reference to the images used.
This is of course closing the stable door after the horse has bolted but still...its a good reference.
The .mtl file can be edited to included a ref to the image files. This isn't a practical solution by any stretch but it could certainly be used in an emergency.
The 3dsMax exported .mtl file contains the following data for each material:
newmtl my_diffuse_mat
Ka 0.525500 0.431400 0.031400
Kd 0.525500 0.431400 0.031400
Ks 0.350000 0.350000 0.350000
Ns 32.000000
d 1.000000
Tr 0.000000
The suffixes 'a', 'd', and 's' after the initial 'K' denote the property of the material they refer to.
'd' is 'diffuse'.
's' is 'specular'.
etc.
The image reference is missing from this list but uses a similar naming convention for each map.
PS outputs an .mtl file something similar to this:
newmtl my_diffuse_mat
Ka 0.525500 0.431400 0.031400
Kd 0.525500 0.431400 0.031400
Ks 0.350000 0.350000 0.350000
Ns 32.000000
d 1.000000
Tr 0.000000
map_Kd my_object - diffuse_image.png
"map_Kd" refers to the image file used in the 'Diffuse' map slot.
"my_object" refers to the object the material is applied to.
Then the image ref....this is relative to the .mtl file.
I couldn't get PS to accept this convention when used with the OP's file, which is strange, but for a file produced solely in PS it works fine.
What DOES work in PS is to remove the object reference but then it does tend to apply the same material to several different objects.....ho hum.
So....thats what I've tried and failed with.
I suggested to the OP that maybe using another app to open and then save out a .obj file may result in the .mtl file being written with the image references....I've never had to use another app than 3dsMax so I don't know what other apps would do this.
Just as an added piece of info the images used in a PS material for the properties of that material can be changed or edited from the properties panel once the material for the object in question has been selected in the 3D panel.
Any property with either a 'Folder' icon, (No image assigned), or a file icon, (Image IS assigned), can have an image as the map to define the property.
Also, hovering over the icon will, (Eventually.....sometimes), show you a very small preview of the image.
Map slots for the properties of a material:
[ATTACH]60171[/ATTACH]
Regards.
MrToM.
