Digital Data Handling

The analysis and interpretation of remote sensing data by manual means has much to recommend it. For example, the trained human eye can identify a very wide range of imaged features with both ease and accuracy. Consequently the interpretation of aerial photographs, space photographs and other forms of remote sensing imagery is, perhaps, still best carried out by hand if the data sets are small and budgets are low. But the volumes of data generated by new remote sensing systems are growing rapidly, and already far exceed the capabilities of trained interpreters in some environmental fields. For example, it has been estimated that a single low-altitude Earth-orbiting satellite, such as any of the NOAA weather satellites, has yielded something of the order of 10¹⁰-10¹² points of new data every day. Earth resources satellites now being built will be capable of even greater outputs, yielding in excess of 500 million data bits per second, i.e. between 10¹³ and 10¹⁴ new units of information daily. Still further increases may be expected as transmission bandwidth restrictions are eased.