62 textures and it works!

As part of an introductory 3D course my students had to make a medieval building with Blender v2.8. To facilitate the assessment of these 43 students, each had to create their UV texture. I then lightened the render by creating textures for Mask type transparency.

Which increased the upload to 62 textures! I was amazed that Sketchfab could handle such a large number of textures. Your technology on the web continues to amaze me!


An observation that I would like to share: my students had to experiment individually with their building on Sketchfab and some pointed out to me that their texture was missing even if it had been packaged in Blender v2.8. This is not a real problem since they can be added later.

When I put online the .blend scene containing the 43 buildings, I also had textures that were missing but also images of textures associated with the bad nomenclature. Let’s explain: a texture used for its RGB layers called “Bob.png” could have as complement “Bob_MAT.png” for the opacity mask image.

On some buildings, the image used by Sketchfab for the opacity was called “Bob_MAT.png” but the texture and his thumbnail was in fact “Bob.png” in the texture manager. By deleting “Bob_MAT.png” with the texture manager Sketchfab also deleted “Bob.png” and I had to download the two images. Then, when I applied the newly downloaded texture to a model that contained more than one UV map, it was the bad UV that was exploited.

It is not complicated to adjust. It’s only that moment, I thought it wouldn’t work pcq I used too many texture images.

In the context of my introductory course, the project seems very interesting to explore on Sketchfab in virtual reality.


Hello Jean Philippe, and thanks for your feedback.

I have made some tests with the original .blend file you uploaded to Sketchfab, and here are a few points that may help you for future uploads:

Use Principled instead of Diffuse for the BSDF node.

Sketchfab support for Blender 2.8 files uses the Principled BSDF node for texture parsing, as our main PBR inputs (base color, roughness, metalness, normal map…) are nearly identical to the Principled node inputs, and we discarded the support for the Diffuse node in our support of Blender 2.8+ files.
As some of the houses that lacked textures during the upload use a Diffuse node, their textures got discarded during the processing.
I am not sure we will add the support for Diffuse nodes back, as the Principled node is now the default material, and is meant to become some kind of “ultimate” node in Blender.

I’d therefore advice you to encourage your students to mostly rely on the Principled node if possible (although that might be a lot to “ask”, this comes with the “bonus” of PBR support :wink: )

One model on which you can notice this in the original .blend file is called “poteau_UVmap”.

Base color and opacity textures not exported

Due to the file format (GlTF) we use for the Blender to Sketchfab conversion, we try to pack the base color (RGB) and alpha (A) textures into one single image (RGBA) if they are separated image in Blender node editor (that’s a requirement of the GlTF format).
This approach usually works fine, but has a major issue: two images with different sizes cannot be packed together, therefore getting discarded during the processing of the .blend file !

We might try to fix this by rescaling images according to the highest resolution (example: packing a base color of 2048x2048 with an alpha of 512x512 would result in a final image of 2048x2048), but I can’t promise you anything about this, as this hypothetical behaviour could create other issues (for very different image sizes for instance).

For now, your best bet is therefore to create the opacity masks with the same resolution than the base color textures in Blender.

Selecting an UV map

Maybe I unnderstood your problem wrong, but in the material tab of the 3D settings, you can actually choose to which UV map your texture will be linked to, if the linked mesh has multiple UV maps available of course. Here is a screenshot of the setting:

Once again, I might have misinterpreted your issue on that point, do not hesitate to let me know if that’s the case :+1:

Hope this helps !

PS: I love this idea of merging your students creation into one model to showcase their work, it’s a very nice approach, and must be motivating for them !

PPS: I must admit I gave up looking for them and used the model inspector to find the crown and the magnificent scepter hidden in the scene :wink:


Bonjour Loic,

Thanks for your explanations.

For forum readers who don’t want to read everything, here is my suggestion: For better optimization of transparent textures, use the texture for opacity in Mask mode with an optimized .png image with only 2 colors (black on transparent background).

Loic’s previous text and my recent experiences tell me that it’s easier to package in Blender than the Base Color texture images and to download the images optimized for the opacity masks separately.

I followed your advice and I ask my students to limit themselves to the Principled BSDF. I believe Sketchfab is right to drop the Diffuse BSDF. However, some students use tutorials on the web that unknowingly are outdated over time.

I loaded the project again on Sketchfab “Forum Test TX Temp”.

Base color and opacity textures not exported

Texture missing (2 buildings): They use a .jpg 2048 format based on color and a .png 1024 format on the opacity mask. (as you explained in the previous post)

Bad conversion (GIFT as you explained) on 7 buildings: In my upload, what differs is the number of colors in the compression. The mask images are all optimized in 2 colors. We use the Export command for the Photoshop web and the Base Color images use a number of colors adapted to the content (16-32-64) as low as possible. The sizes and formats are identical.

Transparent Matte texture not activated in Sketchfab on 4 buildings: 3 buildings use a .jpg format based on color and a .png format on the opacity mask. The only difference for the 4th building is to use two layers of textures superimposed on the same face (base color background, transparent tx 2nd layer).

Selecting an UV map

At our school, we use the French version of Blender. Despite my caveats, I have students who work at home with the English version. When they create UV unfolders in both versions, they unwittingly create 2 UV maps.

For some buildings, when I uploaded a new texture image, I didn’t notice that Sketchfab had changed the selection of the UV map. I didn’t immediately understand the problem and initially I thought Sketchfab couldn’t handle so many texture images.

About the 1st post

The original purpose of my post was to say that Sketchfab can support so many texture images. For the readers of this forum, this may seem useless but in a school context where everyone is evaluated on his personal production, inevitably there is a high number of texture images.

Maybe this project will inspire other teachers.