Intersecting geotiff with another one using alpha-channel (or nodata value) in GDAL?

Question

I have two geotiffs related to one location but with different areas covered:

1.

2.

How can I intersect their opaque parts into single geotiff like that?

Answer 1

Note: This solution is working for single band image only

If you have multiple bands, you may repeat this for each band adding -A_Band and -B_Band options and then gdal_merge.py -separate the bands.

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You should be able to do this:

(We assume NoData Value of your rasters is 0)

gdal_calc.py -A file1.tif -B file2.tif --NoDataValue=0 \
--calc="A*(A>0)+B*logical_and(A==0,B>0)" \
--outfile=outfile.tif

Explanation:

• A*(A>0): if A is not Nodata, will be A*1, else A*0
• B*logical_and(A==0,B>0): if A is NoData and B is not Nodata, will be B*1, else B*0.

(This will always prefer A over B).