use for navigation but the Doppler navigation is under trial. T’he Decca navigator is in use 
for positioning of the camera exposure station and for general orientation. A special Decca 
survey chain is set-up in the Netherlands for the Delta Hydrographic Surveys and is in 
regular use. Another Decca survey chain is set-up in New Guinea and is working regularly 
for hydrographic surveys as well. 
Compasses are the magnetic compass, flux gate compass, gyro compass and astro 
compass. 
Regarding photographic processes various emulsions are in use. In most cases the fol- 
lowing films are applied: Gevaert Aviphot Pan 33 and Gevaert Aviphot Pan 30. The glass 
plates for the RC 7 cameras are Gevaert ultraplan Aviphot Pan 30. 
In the I. T.C. physical laboratory research has just started on the evaluation of image 
quality by the application of techniques developed in tele-communication by means of the 
contrast transmission function. This work is still in its early beginning. The I. T.C. will 
develop in the near future a sinus target which will enable this laboratory to determine in 
a relatively easy way not only contrast transmission for lenses of the cameras and for 
emulsions, but also of all other elements which determine the image quality as observed 
by the human eye. Although this technique is still in its infancy it is believed that the 
theory is sufficiently advanced to present a sound basis for future practical quality criteria, 
anyhow much better than the usual expression of a number of lines per mm. Itis obvious 
that this CTF will also be determined for the standard type of diapositives, contact and 
enlarging papers. 
Various types of contact printers are in use. Experiments are being carried out in the 
I.T.C. with dodging printers and with the image formation properties with dodging in 
general. It was found that the scanning spot of the Cintel Printer, which provides the 
printing light intensity via the electronic feed-back, has an effective diameter of about 
10 mm. Other important facts were discovered regarding the Kel-O-Watt dodging printer. 
The most unfavourable of these was that the dodging effect in case of printing on paper 
is very small because the infrared waves do not penetrate the paper. Some of these results 
will be reported in more detail at the congress. 
CHAPTER II. PLOTTING INSTRUMENTS 
The number of plotting instruments in this country has increased considerably during 
the past four years. The Cadastral Service obtained its stereoplanigraphs C 8. The Survey 
Department of the Ministry of Transport and Waterstaat bought a Galileo Santoni Stereo- 
simplex III and K.L.M. Aerocarto a Wild Autograph A 7 K in order to be able to restitute 
also the photographs taken with the Zeiss twin camera. The International Training 
Centre for Aerial Survey improved its collection by purchasing the Thompson Watts 
plotter, the rectifier SEG V, the Nistri Fotostereografo Beta 2, the Nistri Photo-Mapper, 
a Wild Autograph A 9, a Wild Stereocomparator with complete coordinate recorder E K 4 
and a second Zeiss Stereotop. Its Zeiss Stereoplanigraph C 8 was in 1959 provided with 
the latest electrical devices and with a pair of plate holders for 9 x 9 inch and 6 inch 
principle distance with compensation of distortion for Aviogon lenses. The Wild Auto- 
graph A 8, delivered originally in 1953, was replaced in 1959 by the latest model. The 
I.T.C. purchased in 1959 the Russian Drobyshew Topographic Stereometer. The collec- 
tion of the Geodetic Institute of the Technological University was increased with the 
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