However, different levels of decision-making managers need different scales of land use map, so it's necessary to perform map generalization on large scale land use map.

The experiment was made on base of workflow of aerial photogrammetry, the experiment result shows that the digital image can produce large scale map, and several conclusion is induced at last.

In traditional reservoir capacity calculation, a planimeter is used to obtain a reservoir capacity from topographic maps and large scale topographic maps are needed if high accuracy is required.