860 
On stereo imagery - apart from observing details on both strips, near range and 
far range - the three dimensional image obtained will add an extra dimension. 
Morphological, morphometrical, and geological interpretation can be carried out 
with more confidence on stereo images. The parallax differences make measure 
ments of slope angles and altitude differences possible with a reasonably high 
precision. 
SLAR survey companies have not paid sufficient attention towards stereo vision 
of radar images. Therefore certain deformations in the stereo image have not 
yet been eliminated. The three most important are: 
1. Short-wave rolling effects of the landscape due to slight sideways movements 
of the film or tape transport over the CRT, adding parallax differences. 
2. Longer-wave rolling effects due to slight sideways movements of the film 
transport in the correlator (only for systems using a correlator). 
3. Long-wave rolling effects due to non-parallelism of the flightlines. 
The rolling effect is recognizable by terrain elevation superimposed on the relief 
in an across-flight zone over the entire strip. It might be seen that a river flows 
up and down hill for example. This effect may influence the interpretation detri 
mentally. The first two errors can be eliminated by mechanical improvements of 
the equipment. Stereo vision of radar imagery has obtained little attention up to 
now. These growing pains in the equipment have therefore not been surmounted 
as yet. 
REFERENCES 
CRANDALL, C. J. , 
1969 
KOOPMANS, B.N., 
1972 
KOOPMANS, B. N. , 
1973 
KOOPMANS, B. N. , 
1974 
LEBERL, F. , 
1973 
LEWIS, A. J. , and WAITE, W. P. , 
1973 
Radar mapping in Panama. Phot. Eng. , 
v. 35, 7 - pp. 641-646. 
Notas de clase sobre radar. Centro Inter- 
americano de Fotointerpretacion, CIAF, 
Bogotá, pp.17. 
Drainage analysis on radar images. ITC- 
Journal 1973-3, pp. 464-479. 
Side-looking Airborne Radar Images for 
Thematic Mapping. Readings in Integrated 
Surveys, Publ. ITC-UNESCO Centre. In 
press. 
Radargrammetry for image interpreters. 
ITC Publ. , Enschede, Holland, pp. 136. 
Radar Shadow Frequency. Photogr. Eng. , 
v. 39, 2 - pp. 189-196.