ISPRS Commission III, Vol.34, Part 3A „Photogrammetric Computer Vision“, Graz, 2002 
  
In Mapvision 4D calibration, a steel plate, sized 200 mm x 200 
mm x 20 mm, whose flatness is better than 2 pm, has been 
tested. In practice, the plane is observed in 5-7 different 
positions, always observing about 100 regularly distributed 
points from the surface of the plane. This makes the equation 
system of the calibration larger, but also guarantees a 
homogeneously straight coordinate system. 
When calibration measurements and actual operational on-line 
measurements are made using different methods under different 
lighting conditions, the 3-D scales of the respective 
measurement systems tend to be slightly different. Therefore, it 
is also reasonable to only fix the calibration distance to the 
nominal value, and adjust the final scale of the 3-D coordinate 
system only afterwards in an absolute orientation using a known 
3-D object. The exact dimensions of the object have to be 
determined separately, e.g., using a high precision coordinate 
measurement machine. The corresponding dimensions have to 
be extracted from the measured point cloud too, using a suitable 
3-D modelling program, in order to get the scale difference 
correctly adjusted. 
4. CONCLUSIONS 
This article presents the main principles of the calibration 
method used with a new optical Mapvision 4D measurement 
machine. The calibration is based on precise analytical 
photogrammetry, and it takes into account all reasonable effects 
that can occur during image formation from the object to the 
digitized video image. The calibration is made using free- 
network bundle adjustment, which is constrained using known 
distances and points on precise planes. Hence, the 3-D 
measurement accuracy of Mapvision 4D system comes solely 
from its sophisticated calibration method, rather than from any 
high precision machinery. 
References 
Haggrén, H. and Heikkilä, J., 1989. Calibration of Close-Range 
Photogrammetric Stations Using a Free Network Bundle 
Adjustment. The Photogrammetric Journal of Finland, 11(2), 
pp. 21-31. 
Heikkilà, J., 1997. Accurate camera calibration and feature 
based 3-D reconstruction from monocular image sequences. 
Dissertation, Acta Univ. Oul. C 108, University of Oulu, 
Finland. 
Niini, I. (2000). Photogrammetric Block Adjustment Based on 
Singular Correlation. Dissertation, Acta  Polytechnica 
Scandinavica Ci 120, Helsinki University of Technology, 
Finland. 
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