RAQ: How Does Image Resolution Relate To Map Scale?
Will it Work? First, 20cm imagery is not the same as 1:20 map scale. Maps are created with mix and match combinations of data sources. Each source may be fine on its own, but will the information make sense in the final composition? If you trust the source data providers are reliable and you've got a handle on the datum and projection issues but the finished map looks awful, consider mismatches in scale.