Is Sketchfab using image files that have been deleted?

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#1

Hi Sketchfab team,

I have a weird issue when trying to upload a Blender file. (Both uploading the .blend file and while using the Sketchfab upload addon )

1: I’ve uploaded a draft model of a gun, the sight optic used a .png file to display the HUD.

2: I’ve deleted this model from my Sketchfab profile and continued work on the model in Blender. In Blender I’ve replaced the .png file with two .jpg files to simulate the transparency in Sketchfab by using one .jpg for the base color, the other one for the alpha mask.

3: Uploading the new model still shows a .png file, see image below. (the weird thing is that I aslo did not name the file like that.)

image
image1310×921 120 KB

4. Subsequent upload always still had the .png visible in the 3D editor.

5: I’ve tried various attempts:
I have deleted the .png file from my computer, I have renamed the .jpg files.
I checked my Blender file for “hidden” image files, I can only see the two .jpg files.

image
image1085×934 144 KB

I’ve copied the Blender objects to a new Blender file, I’ve tried downloading a new Blender version
Nothing seems to work.

Whenever I upload the model I get to see that mysterious .png
So now I wonder, is Sketchfab storing image files somewhere and then trying to apply them to newly uploaded models?

It’s quite a weird issue I’m having, I hope I made some sense.

Cheers,
Ed

#2

Hi @CSMajorBoris ,

Interesting observations but unfortunately there is nothing magic behind this, it’s just caused by the processing pipeline we have for Blender.

When you send a blender model (through direct upload or using the exporter), a .blend is sent to Sketchfab. Then the processing generates a glTF from that .blend and forwards it to the next processing steps (blend format is proprietary and complex so we get rid of it as soon as possible in favor of an easy transfert file format).

The only way to store transparency/opacity in glTF is through the alpha channel of baseColorTexture, so whatever the way to create transparency in Blender, it will be converted to RGBA (RGB=diffuse, A=opacity) and because of that alpha channel, PNG format will be used.

So this texture is not reused, but created each time :slight_smile:

2 Likes
#3

Ah, interesting.
Thanks for the clarification @waleguene