INTRODUCTION 
Purpose 
report presented to the XII Congress of the International Society of 
Photogrammetry, July 1972 (Fischer, 19723 to 1975. Asa result, systems, 
procedures, and references reported in 1972 are, with rare exception, 
not repeated herein. 
Organization 
This report is divided into two major components: I) a general 
overview of developments and proposal satellite programs; and 
II) discussions of developments in the infrared, microwave, and 
luminescence fields, both satellite and airborne. 
What is Remote Sensing? 
Remote sensing has been variously defined but basically it is the 
art or science of telling something about an object without touching. it. 
Based on this definition, any remote observation can be placed within 
the remote-sensing umbrella. It may clarify understanding, however, to 
contrast remote sensing with data derived for specific purposes, with 
Specific systems, for example--conventional photography acquired for 
conventional photogrammetric purposes. 
Basically, conventional mapping photogrammetry is concerned with 
the existence of a given planetary feature or features, their size and | 
shape at a given time, and location of these features with respect to 
the sphere. In contrast, but building upon this foundation of location, 
remote sensing addresses three general problems: What is it?. why is 
it?, and how does it change with time? 
How Remote Sensing is Used 
For some purposes, such as surveying the distribution of relatively 
large (1/4 ha) bodies of surface water and their change with time, 
remote-sensing data can provide the needed information directly. For 
most applications, however, and as implied in the previous paragraph, 
remote sensing builds upon an integration of its own capabilities with 
those of other extant measurement techniques, arts or Sciences--for 
example, force fields and earth sciences, such as geology and hydrology. 
This integration is being accomplished visually and by computer