I am new to using the graphic modeler and I do not know how to do certain actions.

I have several treatments to perform on the basis of a buffer zone. Indeed, I have to polygonize 2 raster (which we will call A and B). After the polygonization of "A", other treatments follow each other using A. But after the treatment of "B", nothing continues. (I'll let you see the diagram to better understand)

Currently, the polygonization treatments are one by one. Now, in order to save time, I would like the polygonization of A and B to be done at the same time, in parallel. Do you know if it is possible to do this. And if yes, how? If it's possible only on Python, I can export the Model Builder's script and add the function.

What I have <--What I have :enter image description here<--What I would like to have.

  • 1
    The modeller simply represents a workflow of the available QGIS tools. No tool allows the simultaneously processing of two layers. Also, why do you think this would save time, since you obviously have different input layers. – Erik Apr 17 at 11:35
  • Thank you for your response. So I'm going to save many time because treatment A does not need treatment B. They are independent of each other. On the other hand, they have polygonization in common. And this is very long. So the fact of this task at the same time divides by 2 the calculation time. If I understood correctly it is impossible with the model builder. But what about using python? – ANG64 Apr 17 at 12:31
  • You have different inputs to the polygonization, so there is no way you'd save time. – Erik Apr 17 at 12:43
  • I think I am not clear in what I say / want. So I give an example: If I do my process manually I can start the polygonization of A and B at the same time. Juste repeat 2 time : Raster-> conversion -> polygonization. and it's work (imgur.com/a/Xmn1XUY). But it's manually. So, do same things but automatically. Thank you for taking your time for me. – ANG64 Apr 17 at 13:10
  • Yes, but that are still two different instances of vectorization. – Erik Apr 17 at 13:31

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