CALSPAN CORPORATION
John E. Walker
As a result of over fifteen years of research at Calspan (formerly
Cornell Aeronautical Laboratory, Inc.), a technique of photometric
quantification and measurement is now a reality. The technique has
been given the title of Photometric Interpretation and is described
in U.S. Patent #3,849,006 (1974).
Simply stated, the technique is based upon the realization that no
matter which or how many of the numerous attenuators of energy are present
in the optical path between the recording media (tape or film) and the
ground, they can only result in two effects on the image photometric
properties. One effect is multiplicative, i.e., modulation of the energy
coming directly from the ground object, and the other is additive, i.e.,
the addition of energy not coming directly from the ground object. The " )
further realization that there are images present in practically every
remotely sensed scene that can be analyzed to derive an accurate value
for these effects led to the development of this very practical method
of photometric calibration of remote sensor imagery.
Applications of the technique to various interpretive problems are
described in the following references:
1. Piech, K. R. and Walker, J. E., 1974. U.S. Patent #3,849,006.
Nov. 19, 1974 :
2. -7*:.1971. . Aerial Color Analyses of Water Quality. Journal
S&M Div., Proc. ASCE. Vol. 97, No. SU2, November
3. --— 19722. ‘ Outfall Inventory Using Airphoto Interpretation.
Photogrammetric Engineering, Vol.38 No.9, September
4. -—— 1972b. "Thematic Mapping of Flooded Acreage. Photogram-
metric Engineering, Vol. 38, No. ll, November ¢ b
5. --- 1974. Interpretation of Soils. Photogrammetric
Engineering, Vol. 40, No. 1, January
6. Smith, P.G., Piech, K. R., and Walker, J, E. 1974.
Special Color Analysis Techniques, Photogrammetric
Engineering, Vol. 40, No. 12, December
7, Walker, J. E. and Dahm, D. B.. 1975. Atmospheric Corrections
for Satellite Water Quality Studies Soc. Photo Optical Inst,
Engrs. Vol. 51
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