STL / OBJ Import

Jason Galterio

I have this weird thing going on, where I am sure I am missing something tiny...

I have STL files. I take them into MeshLab. I then export an OBJ file. I import the OBJ file into DS.

Everything works, no issues so far.

Within DS if I try to apply a Shader to the OBJ, nothing really happens. If it is a basic shader (Color, settings), that generally works.

What doesn't work is any shader using an image map. Or any shader that has that procedural trickery to vary up the base color.

I have tried tiling, both up and down, to no avail. I've tried different import and export options, but no change.

It's almost like the OBJ file is in the scene, but not in the scene...?

I think it has something to do with the UV mapping. Like the OBJ doesn't have a UV map, so the image map file has no where to "hook" to.

Richard Haseltine

I don't believe that STL files have UVs in most cases, you will need to UV map the mdoel if you want to apply textures (or procedural shaders that rely on the UVs).

richardandtracy

In all cases where the package meets the commonly held standard there is no place for texture mapping. 

In the binary STL file there are only 2 unused bytes per facet. Some packages use these for a 16 bit facet colour. All other packages do what they should with them - ignore those bytes. The only other data in the file is an 80 byte header, an integer for the number of facets, then the facet data comprising 3 floating point numbers for a facet normal, then the floating point co-ordinates of each of the three facet corners. That's it, no space for texture mapping.

So, if you are going to use the resulting file in DS, you do need to do texture mapping somehow.

Regards,

Richard.

 

Jason Galterio

Thanks. You both confirmed what I was suspecting. Now I need to figure out how to create the texture mapping with the tools I have.

I've tried in MeshLab, Unwrap 3D, Silo, and DS, but no of those seem capable of doing the deed.

andya_b341b7c5f5

Unwrap3D can certainly be used to do the UV mapping.  The difficulty level will depend on your model.  Silo and MeshLab, I don't know about, but DS certainly does not offer this.

You can avoid the UV mapping if you stick to procedural shaders e.g. all the Iray ones that DS includes by default.  You will only need to create (at least) one surface (perhaps there will be a single default one for the whole model), and then apply a shader of your choice to each surface.