865 
angular 
range of 
view 
scale 
in y 
factors 
-60° 
1000 
tO 
to 
+60° 
100000 
-60° 
100 
to 
to 
+60 
10000 
O 
o 
CT> 
1 
100 
to 
to 
+90° 
100000 
- 5° 
>1000000 
to 
satellites 
+ 5° 
-60° 
to 
+60° 
0 
"to 
+ 5° 
% 50000 
and 
>1000000 
satellites 
-60° 
10000 
to 
to 
+60 
1000000 
semi 
annulus 
constant 
angle 
10000 
to 
1000000 
o 
LO 
100000 
to 
to 
60° 
1000000 
o 
LO 
100000 
to 
1000000 
70° 
45° 1000 
to to 
70° 10000 
2. Production of Geometrically Correct Thematic Maps for, e.g., agriculture, 
land use, oceanography and geography will be important to somewhat lower 
accuracy requirements than for topographic mapping. But a geometric 
restitution is required especially for scanners with panoramic distortion 
since depicted detail could not otherwise be correlated visually to 
reality. Despite the relatively low ground resolution of 1 to 20 m 
attainable from low flying heights, multispectral scanners due to their 
high spectral resolution offer the best possibility for object 
classification. Geometrical restitution of satellite multispectral 
scanner images is less of a problem, since images are already reproduced 
in bulk-rectified form and since topographic displacements are negligible. 
The geometric contribution for thematic mapping will best have to be 
made at the preprocessing stage. Studies are required to test present 
procedures used for producing ERTS imagery and other types of images 
obtained by multispectral scanning. 
3. Production of a Geometric Base for Semiautomatic or Automatic Comparison 
of spatially, spectrally and temporally different images to and beyond 
resolution limits is a requirement for all types of imagery, especially 
for images from multispectral and IR scanners. Only then change 
detection may be studied with image analyzers or computer analysis. 
These problems are currently underestimated by the user. 
It is the aim of the working group to deal with problems of 
geometrical restitution for the 3 mentioned purposes. This work must be 
carried out in various steps: 
a) Analytical Analysis 
It consists of the formulation of a mathematical model, the 
measurement of image coordinates with a suitable instrument (compara 
tor) and a test in which computed ground coordinates derived from the 
measurements via the mathematical model are compared with known 
ground coordinates in a test area. 
Tests of this nature have been conducted by members of the working 
group. They are being published (in English) in the journal of the 
German Society of Photogrammetry "Bildmessung und Luftbildwesen" 
Vol. 1975/1. These tests have established that differential 
rectification of the images according to correction functions 
derived from ground control may result in geometric position 
accuracies of 3 times the resolution for radar, of 2 times the 
resolution for thermal and multispectral scanners used from aircraft 
and of slightly better than resolution for satellite scanner images. 
Standard aerial photography permits the evaluation of the geometry 
to better than 1/3 of the resolution. 
In obtaining this accuracy an interpolation procedure is used between 
control points (polynomials, least squares).