Overlaying multiple textures in one I have generated a 3d Modle with Meshroom and when I import it in Blender it has three Materials on it each with one of the three textures generated:

I am trying to combine the Three materials into one but whatever I try it does not work properly:

I have tried to get a mask from the black of the images but it didn't work either.

Here is the model with the images. Thank you for your time.
The model might look slightly different because I have already cleaned the mesh up a bit. And I also was not able to export a single texture in meshroom it crashed.
You can do it by two ways.
First notice the UV map:

It is made as 3 parts, each corresponding to a texture.
So you can either use the new UDIM features of Blender or calculate it in a node tree.
Using UDIM tiles
Create a UDIM texture in the image editor. Check &quot;Tiled&quot;:

Add each of the textures to it (in the correct order):

From the image tab on the right, open the first image from disk with the folder button.
Once done use the &quot;+&quot; on the right of the tile list. Open the second image.
Use the &quot;+&quot; and open the third image.
At the end, you should see that:

Now you can simply use the UDIM image as a normal image in the material editor:

Without UDIM feature
If your version of Blender does not have UDIM.
You can use the following nodes, testing the UV map parts with math nodes.