As we have already seen in previous chapters, even a simple analysis may require several steps. In real-life applications, much more complex tasks exist, and they involve and combine different processes of analysis. Running them manually is a time-consuming process, and it may take hours to complete. Things become even worse and complicated when you need to run this analysis several times with different input data or use the same data with different settings.

This is where the QGIS Processing framework comes to help. It allows us to automate repeated tasks and create new complex algorithms that involve different types of data processing. With the help of the Graphical modeler from the Processing toolbox, we can easily create our own algorithms by combining existing algorithms. The created model can be executed like any other Processing algorithm, and even used as part of another, more complex model.

There are two common ways of opening the Graphical Modeler: