1. A method of providing a geometrically corrected large angle whiskbroom scan of a portion of the earth's surface comprising: providing a linear array of radiation-sensitive detectors mounted in a low earth orbiting satellite oriented along the direction of the satellite's ground track; scanning a portion of the earth's surface with the detector array to define on said surface an irregularly-shaped swath which represents a field of view of the array; defining a regularly-shaped ground area of interest within the field of view of the array; dividing the ground area of interest into a plurality of pixel lines extending generally perpendicularly to the linear array, the number of pixel lines being fewer in number than the number of detectors in the array; subdividing each pixel line into a plurality of pixels, each pixel encompassing at least a portion of a field of view of one or more of the detectors in the array; selectively combining outputs from the detectors to provide a data signal representative of each individual pixel in each pixel line; and reconstructing a representation of the ground area of interest from the data signals, the in-scan detector subtense corresponding to a distance of at least approximate 500 meters along the ground.