Aerial photographs can be made with virtually any type of camera. The simplicity operation and low cost of purchase make the 35-mm camera ideal sensors for small area analysis. For large areas, over 100 different models of precision built aerial cameras are currently in use.
Clouds often block satellite images.
So decisions can be made in a timely manner. But the images are usually expensive and take considerable time between image acquisition and delivery to the user. Satellite sensors have the advantages of good geometric and radiometric integrity. Accurate meteorological parameters such as cumulative growing degree-day maps, evapotranspiration maps, snow accumulation, rainfall and others are good satellite products. Image registration difficulties are a limiting factor.