the y-parallax after the orientation of 3.8 um corresponding to approx- 
imately 0.15 of a pixel in the image. In a bundle adjustment the stan- 
dard error of the matching was 3.4 um, which should be compared with 
2.8 um using monocomparator measurements in the same investigation. 
In an investigation concerning automatic parallax measurements in simu- 
lated SPOT-images (1985) the author of this report came to the conclu- 
sion that the obtainable two-dimensional matching accuracy with the 
methods used, one correlation coefficient method and one least square 
method with a window size of 17X17 pixels, was around 1/3 of a pixel 
expressed as root mean square deviation. It was also concluded that the 
error caused by radiometric differences between the images was larger 
than the errors caused by the geometric differences between the images. 
THE IMAGE MATERIAL 
The images in the investigation were chosen as examples of practical 
applications in photogrammetry. Large scale and small scale aerial 
photographs and an example from close range photogrammetry (rock tunnel 
wall). The following image data sets were used (the check points are 
marked with crosses in the images). 
  
Low. (above) An image pair in a scale of 1:4,000 of a suburban area 
near Stockholm. The overlap in the strip is 607, the camera constant 
152 mm and the base-to-height ratio 0.65. The photographs are of good 
quality and manual measurements are easy to perform. The images are in- 
sufficiently exposed in the shadows. Because of houses and other ob- 
jects stereo shadows are common. 
  
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