SORA-MP: A PROGRAM FOR DIGITALLY CONTROLLED MAP 
TRANSFORMATION 
  
  
  
  
   
   
  
   
   
   
   
   
  
  
  
  
   
   
    
    
   
   
    
   
   
   
   
    
     
  
J Jansa 
Institute for Photogrammetry 
Technical University Vienna 
A-1040 Vienna (Austria) 
E Vozikis 
R&D Department 
Wild Heerbrugg Ltd 
CH-9435 Heerbrugg (Switzerland) 
Commission III 
Abstract 
Digitally controlled differential rectification allows a map drawn in any 
projection to be transformed into any other projection. For this purpose, 
the Institute of Photogrammetry of the Technical University Vienna has 
developed a program (SORA-MP) for Wild Heerbrugg Ltd. 
When the equations of image formation for the projections concerned are 
known, strictly mathematical transformation is possible. If the transfor- 
mation laws are unknown, a non-parametric interpolation method can be 
used in which a choice is possible between purely affine transformation, 
transformation based on a polynomial system or, in more complex cases, 
transformation by interpolation by the method of least squares. 
Since the original map is not always available but may be a photographic 
reproduction, the program makes provision for taking into account affine 
(paper and/or film shrinkage) and perspective (photographic image) 
deformation. The software is modular in structure to allow the user to 
define map projections as required. 
1 Introduction 
Digitally controlled differential transformation opens the door to a 
large number of possible applications in the field of optical transfor- 
mation. As regards the instruments available in this context, the Wild 
AVIOPLAN OR1 differential rectifier (Stewardson, 1976) occupies a para- 
mount place. The control data required for this are provided by various 
SORA programs (Vozikis and Loitsch, 1982). Whilst the production of 
conventional orthophotographs (SORA-OP) and stereomates (SORA-OPS) is 
without doubt the most important field of activity, a number of other 
applications have provided further evidence of the outstanding flexibi- 
lity of the OR1/SORA system. 
These have included the rectification of plane objects (Vozikis, 1979; 
Vozikis and Loitsch, 1980), the development of regular surfaces (Kraus 
and Tschannerl 1976; Vozikis 1979), rectification of multispectral 
scanner photographs (Kraus, 1975; Jansa, 1980) and map transformation 
(Bormann and Vozikis, 1982), all of which have proved possible. This 
paper provides information about a new SORA-MP program whose name refers 
to its suitability fo transformation but which in fact can be used