So, I have a land use map that I need to digitize. The changes in the map is very fine so it will take a long time to manually digitize it. When I used the Raster > Conversion > Polygonize (Raster to Vector) function, the output shapefile is just black. I tried bands 1 to 4 but same result.

I also tried SAGA's Raster values to points and GRASS' r.to.vect but the result is the same: a black shapefile.

Can anyone help?


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  • 2
    If it is a picture composed of three bands (RGB color), then polygonize will not work. You need to digitize the land use map manually. – ahmadhanb Apr 7 '20 at 8:42
  • Didn't know that. Idk if this is obvious then what type of raster would the function work if it doesnt accept RGB colors? Thanks, @ahmadhanb. – BallpenMan Apr 7 '20 at 10:27
  • 1
    polygonize works with single band raster not multi-band raster. – ahmadhanb Apr 7 '20 at 11:11

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