(Fig 1: The same image of Ningbo, China taken on the same day. Optical imagery is on the left. SAR imagery, which can see through clouds, is on the right.)

Not only is the type of sensors used important, but the methods of collection and the measurement approaches can also be essential to building a valuable data product. For instance, the following can all impact quality:

The frequency of collect

Consistent area collects

The use of direct measurement versus estimation and interpolation