24. Masry, S.E. 
Gibbons, J.G. 
Canada 
RECTIFICATION OF INFRARED IMAGERY 
Infrared imagery possesses distortions which increase rapidly towards the edges of the scan lines. These 
distortions render the interpretation and stereoscopic vision of the imagery.difficult. Also, since the distortions 
are non-linear, approximate measurements of ground distances from the imagery cannot be directly carried 
out. 
A method was developed for rectification of this imagery. The orthophotoprinter attachment to the analytical 
plotter was used for this purpose. The method is automatic and can be used with similar printers which are 
computer-controlled. The same technique can be followed to reduce or eliminate distortions of systematic 
nature in conventional and unconventional photography. 
25. McLaurin, J.D. 
United States 
THE SKYLAB EARTH TERRAIN CAMERA 
The NASA Skylab program includes several sensors for viewing the earth: the S-190 multispectral camera 
system, the S-101 infrared spectrometer, the S-192 multispectral scanner, the S-193 microwave system, and the 
S-194 L-band radiometer. These sensors make up the original Earth Resources Experiment Package (EREP) 
and have been described previously. Less well known is the Earth Terrain Camera (ETC), which has recently 
been added to EREP. ETS is an addendum to the S-190 experiment and, as such, is designed to supply 
high-resolution photographs of small areas within the field of view of the other EREP sensors to aid in 
interpreting the data gathered by these instruments. ETC is a frame camera of 460 mm focal length with a 
format size of 115 x 115 mm. The camera system includes image-motion compensation and an f/4 
colored-corrected lens. The expected low-contrast ground resolution of the camera ranges from 10 to 40 mm 
per optical line pair, depending on the film used. The US. Geological Survey intends to conduct several 
experiments with the images from the ETC, including photomapping and map revision at scales of 1:250,000 
and 1:100,000, thematic mapping, geological and hydrological studies of several areas, and geographic studies 
of specific test sites. The ETC will also provide an opportunity to compare imagery of different spatial 
resolutions, which will provide valuable data for use in planning later earth resources satellite sensors. 
26. McNeil, G.T. 
United States 
UNDERWATER PHOTOGRAPHY 
The purpose of the Underwater Photography session is to present to the International Society of Photogram- 
metry the work conducted during the past two years by the Underwater Photography Committee of the 
American Society of Photogrammetry in the interest of encouraging international cooperation in fulfilling the 
Committee’s objectives. 
The American Society of Photogrammetry, fully cognizant of the increased interests and activities in the 
underwater environment, organized the Underwater Photography Committee in December 1969. 
The broad aims and objectives of the Underwater Photography Committee are: 
- To disseminate knowledge and promote education in underwater 
photography, 
- To encourage the perfecting of underwater photography to 
explore and study the ocean, 
- To create a broader understanding of the relevance of underwater photography to other technologies, 
arts, and human affairs and, 
- To exert efforts toward the documentation and improvement of underwater photography standards. 
The Underwater Photography Committee is concerned with all phases of the acquisition of imagery for the 
purposes of photogrammetry and image interpretation.