where the image patterns are strong (and local variance 
is high). 
With the coming of one-meter optical data from 
spaceborne sensors in the next few years, optical 
imagery will approach the precision of radar 
interferometry. Optical data also provide the capability 
to actually see the displacements. Subresolution 
misregistrations in images are readily apparent in video 
displays that flicker multitemporal images (Crippen and 
Blom, 1992). This has previously been used to 
visualize actual displacements along strike-slip faults. 
BENEFITS OF REMOTE SENSING IN GEODESY 
Using remote sensing for precise measurement of 
dynamic processes in the environment has several 
advantages. Firstly, it is spatially comprehensive. 
Millions of measurements can be made across a 
satellite image that covers a region where even a dense 
GPS array would have only a few dozen stations. 
Secondly, it requires no anticipation. Potential 'before' 
and 'after' images are being acquired everyday by 
numerous satellites. No baseline geodetic field 
measurements need be made in anticipation of an 
earthquake (or other event) that might never occur in 
the researcher's lifetime. Thirdly, it is cheap and easy. 
The growing available (and improving) data sets cost 
the user nothing until and unless needed; the expense 
of travel and field logistics can be avoided; and 
researchers can perform their studies at their desk 
when convenient. 
We have coined the term 'imageodesy' to refer to the 
use of remote sensing for the precise measurement of 
dynamic processes across an image. The term is a 
concatenation of the words "image geodesy" and also a 
partial acronym for "Image Multitemporal Analysis 
geodesy". We see great potential for imageodesy as 
terrestrial remote sensing moves beyond the questions 
"What's there?" and "How has it changed?", to the 
question "Where is it going?". 
REFERENCES 
Crippen, Robert E., 1992, Measurement of 
subresolution terrain displacements using SPOT 
panchromatic imagery. Episodes, 15(1), pp. 56-61. 
Crippen, R.E., and R.G. Blom, 1992, The first visual 
observation of fault movements from space: The 1992 
Landers earthquake. EOS, Transactions of the 
American Geophysical Union, 73 (43), pp. 364. 
Massonnet, D., M. Rossi, C. Carmona, F. Adragna, G. 
Peltzer, K. Feigl, and T. Rabaute, 1993, The 
displacement field of the Landers earthquake mapped 
by radar interferometry. Nature, 364, pp. 138-142. 
Peltzer, Gilles, and Paul Rosen, 1995, Surface 
displacement of the 17 May 1993 Eureka Valley, 
California, earthquake observed by SAR interferometry. 
Science, 268, 1333-1336. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996 
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