Brief Report 
on the Results of the Reichenbach Test of Commission C of the OEEPE 
(Concerning the Accuracy of Photogrammetric Coordinate 
Measurement in Mountainous Country) 
By R. Fôrstner, Frankfurt a. M. 
1. Introduction 
At the Lisbon congress, the Reichenbach test was reported upon and provisional results were im- 
parted [1]. Since that time, the work has been concluded [2]. A part of the final results will be 
communicated here. For the sake of continuity, the nature of the geodetic data and photographic 
material, as well as the questions to be answered or elucidated by the test, will be mentioned briefly 
once again. 
The “Reichenbach“ area is in southern Germany, in the „Schwäbische Alb“ and measures about 
3 X 3 km? [5]. The country has altitude differences of almost 300 m and slopes of up to 30%. 
A new triangulation net with over 100 points was established over the area. Starting from these 
points, a further 500 check points were determined. The altitudes were established mainly by trigo- 
nometric heighting. After thorough investigations, the mean square error in position and height 
(estimated value for the standard deviation) was accepted as being less than 2 cm. 
The area was flown using the following four survey cameras: 
5 J 
— Normal angle camera (RMK 21/18) 
— Wide angle camera (RMK 15/25) 
— Convergent camera (2 X RMK 21/18) 
— Wide angle camera (RC 7a 10/14) 
The picture scales are 1 : 8 000 and 1 : 12 000. For the signalization of the check points, square metal 
plates of 25 X 25 cm? were used for both scales. Moreover, the points were marked with additional 
markers, so called “identification markers“, in order to prevent confusion with other objects. 
2. Test Programme 
With the available material, the following questions had to be clarified: 
(1) Point accuracy (position and height) attained with different picture scales and under different 
survey conditions. 
(2) Accuracy of distances under these circumstances. 
Moreover, the following problems had to be solved or examined during the tests: 
(3) Comparison of the accuracy of pictures at different scales. 
(4) Comparison of the accuracy of pictures on film and on glass plates, 
a) at equal scales 
b) with equal coverage per picture, e. g. comparison between pictures on glass plates of 14x 14 cm? 
at scale 1 : 12000 and pictures on 25 X 25 cm? films, scale 1 : 8 000. 
(5 Comparison of the accuracies of normal angle convergent pictures and normal angle verticals. 
(60) Comparison of the accuracies of normal angle convergent pictures and wide angle verticals. 
(7 Comparison of the accuracies of normal angle and wide angle verticals. 
o o 
The solution of each of these additional problems 5 to 7 required the combined processing of two 
different strips. At the same time, this provided material for answering the first two fundamental 
questions. 
13