the disparity map contains numbers in a fixed point format, i.e. the values are scaled. I think it’s four fractional pixels, so the factor is 16.
check if 180/16 = 11.25 is approximately the distance you expect. maybe it’s some other number of fractional bits.
the docs on that are awful, I know. here’s documentation on reproject… which states the factor-16 fixed-point format.