Automatically generate polygons based on conditions

Question

Suppose you have two rasters. I would like to create a number of polygons such that each pixel belonging to each polygon fulfilsthe two conditions.

E.g. condition1: rastera > x; condition2: rasterb < y

The borders of polygons should be placed where the neighbour pixel to each pixel fulfilling the conditions does not fulfil any of the two conditions. This would allow creating a number of polygons where the two conditions are satisfied.

Do you think this is feasible and could you suggest a methodology?

Answer 1

You're basically halfway there. By entering an expression similar to the one in your question into Raster Calculator, then polygonizing your results, you can accomplish this.

Try entering "raster_a@1" > x AND "raster_b@1" < y

Your output will be a binary raster where 1 = conditions met, 0 = conditions unmet. Convert to polygons, then delete the areas with a value of 0.