I have a raster of 36 classes of the land cover in South Africa. However, I only need 4 of these classes and create a polygon out of these 4 classes combined.

I have now used the raster calculator to generate a raster where 0 = the values/classes I don't need and 1 = the 4 classes I need.

How can I polygonize just the value 1 from this raster? Or, how can I polygonize the 4 classes out of the land cover layer directly?

2 Answers 2


Use the raster calculator to select the values you want e.g. yourraster@1 = 4, this will give you a binary output that you can vectorise i.e. cells with a value of 1 being the the cells in your original raster that had a value of 4.


You can polygonize just the 1 values using SAGA's Vectorising Grid Classes tool. Just set Class Selection to One Single Class and set Class Identifier to 1.

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