Measurements were made on two RC5A cameras to explore the spectral 
differences involved in the two calibration methods (figure l 1 ). Transverse colour 
(chromatic difference of distortion) was measured at a number of field angles. 
Results are shown in figure 2. Then the camera was tested on the photographic 
calibrator with »mean noon sunlight» light sources and flattened Aero Super XX 
plates. First the Wild 2X yellow filter was fitted. Next, no filter was on the 
camera but collimator lights were screened with Wratten 13 filters to transform 
the effective spectral sensitivity to about that of the human eye. Results are 
shown in figure 3. 
The differences in image position between the two calibrations are shown in 
figure 4. For comparison, median wavelengths were obtained for curves B and C 
of figure 1 and image shifts between these two wavelengths read from the 
curves of figure 2, were plotted to give the comparison curve in figure 4. This 
procedure is only a rough approximation to the theoretically correct one. How 
ever, the agreement between the two curves is sufficient to confirm that the 
differences found between the two calibration procedures can be attributed 
chiefly to the chromatic differences of distortion of the lens as seen by two 
spectrally different receivers. 
These results emphasize the necessity of calibrating air survey cameras by a 
procedure which closely simulates conditions of use. The error investigated here 
arose primarily from the visual test procedure having the wrong chromatic 
sensitivity. However, similar errors could arise from other departures from 
normal conditions of use. 
P. D. Carman tfc H. Brown: Unterschiede zwischen visueller und photographischer 
Kalibrierung von Luftbildkainniern. 
Die im Jahre 1955 vom National Research Council in Canada mit dem neuen photographischen 
Kalibrierungsgerät durchgeführten Kontrollmessungen an Wild RC5A Kammern zeigten systema 
tische Differenzen mit den auf einem visuellen Kalibrierungsgerät erlangten Werten der Herstellungs 
firma. 
Photographisch bestimmte Bildweiten überschritten gewöhnlich die vom Hersteller angegebenen 
um 0.01 bis 0.02 mm. Die bei der Photographischen Kalibrierung erhaltenen Extremwerte für die 
durchschnittlichen radialen Verzeichnungskurven lagen zwischen 10 und 17 Micron. Das sind im 
Mittel 5 bis 6 Micron mehr, als die vom Hersteller angegebenen Werte. 
Die Messungen wurden an zwei RC5A Kammern durchgeführt, um die spektralen Differenzen, 
die durch die zwei Kalibrierungsmethoden bedingt sind, festzustellen (Abb. 1). In einer Anzahl 
von Bildwinkeln (Abb. 2) wurden die chromatischen Differenzen der Verzeichnung gemessen. Dann 
wurde die Kammer in der üblichen Art photographisch und auch in einer der visuellen Methode 
entsprechenden Weise kalibriert (Abb. 3). Die Unterschiede in der Bildlage, bedingt durch die zwei 
verschiedenen Kalibrierungsmethoden, stimmten überein mit den Werten, die man durch Berech 
nung aus den gemessenen chromatischen Differenzen und den mittleren Wellenlängen von zwei 
entsprechenden Kurven erhalten hatte (Abb. 4). 
Diese Resultate betonen die Notwendigkeit, Kalibrierungen von Luftbildkammern unter annähernd 
gleichen physikalischen Bedingungen durchzuführen, wie man sie später auch im praktischen 
Gebrauch der Kammern vorfindet. 
B. Hallert: A new 
method for the 
determination of the 
distortion and the 
inner orientation. 
(Publ. I Hi) 
B. Hallert: A new method for the determination of the distortion and the 
inner orientation of cameras and projectors. The Grid Method. 
The paper deals with the determination of some important systematic errors 
in photogrammetric pencils of rays, and the complete determination of the inner 
orientation of all kinds of cameras and projectors, X-ray instruments etc. 
The method is founded upon the photography or projection of regular plane 
grids, which are measured with high precision. The projective connection be 
tween the grid points is used for the determination of the qualities of the central 
projection in question. The points are combined in a special way and the method 
of the least squares is used for the determination of corrections to the 6 degrees 
of freedom of the pencils of rays in space from the discrepancies in the coordinate 
measurements. Particularly the radial distortion and asymmetries of the pencils 
1 The figures are not printed here.