th Order 
tortions, 
se linear 
uadratic 
e (Hein, 
ution of 
triangle 
ormed. 
5 of 2nd 
ol points 
tribution 
shape of 
2 4. Topological Relations of Plans 
For the flexibility of handling transformation functions for 
object partial planes f, it is provided , that a subdivision 
along the places or lines of unsteadiness is possible. 
From the view-point of topological relation R it is often 
necessary to subdivide façades in detailed parts f. This 
results in a hierarchical structure G(f), in which a priori a 
classification of transformation functions can be handed 
down. Between the planes f,, f, anf f, exists the relation 
R (strict partial order), if 
fq cfo A fo c fa for all 4, fo,fa € F 
(r R fo ^ f R fa) > f4 Rf (5) 
t Rfa2 f2 f, forallfi,fae F 
is given. 
3. REALIZATION 
3.1Principle of the Procedure 
Inthe foreground ofthe system design stands a high user 
interaction for experimentel working by the creation of 
orthplans. The development of the orthophotosystem 
has the following principles: 
. Interactive displaying of multi images in an industrial 
window environment. 
. Using interactive manipulation for the orthophoto 
production. 
. Interactivetesting oftransformation and resampling. 
. Fast mode for creation of orthophotos in low- 
resolution. 
. Batch-mode for generation of orthophotos in high- 
resolution. 
. Inputof external 3D-models (i.e. DXF from AutoCad) 
into the system. 
. Combination: orthophoto with geometric-data. 
. Using of all built-in image processing tools after 
generating orthophotos. 
° Standard image file formats for outputs 
(i.o. TIFF, VFF, EPSF). 
      
   
   
   
   
   
   
   
    
   
    
     
     
    
   
   
  
    
    
   
    
    
     
     
    
    
    
    
    
   
  
2. m n ntrol Point Handlin 
The object geometry (control) for a digital rectification is 
done by analytical stereo-measurements on a Planicomp 
P3 combined by a CAD-system (AutoCAD), where a 
plane structure is defined by layers. Default attributes 
such as types of transformation can be assigned to the 
planes. The subarea hierarchy with the topological relation 
Ris found out of the CAD-layer structure and transfered 
to the orthophoto system. 
Conceptively all methods can serve for the geometric 
data (measurements at the object, triangulated points 
etc.), which are necessary for single image rectification. 
Geometrical informations, such as the subdivision of the 
fagade struture in limited subareas andthe control points, 
are derived from a 3D-object model. 
The position of control points and the area limits of any 
plane can be transformed back from the 3D-model to the 
image plane, if the interior and exterior orientation are 
known (Fig. 3.2.1). For control points of images, which 
are not contributing to the model, corrections may be 
necessary. 
The free choice of projection planes garantees the 
handling of image mosaics and allows the computation 
of control point positions and of the limits of planes, 
Puy) = fc Y. 2). 
  
3D-Object-Model (World-Coordinates) 
  
  
  
Inverse 
Projection 
Projection 
  
  
= 
—B>| Image plane 1 Ho 
  
— 
© 
—»| Image plane 2 |-o—B>| Projection 
plane 
  
  
  
  
—Pp»| Image planen — ©° 
  
  
  
  
Rectif 
  
  
Fig. 3.2.1  3D-Object-Model 
3.3. Imagehandling and Multiwindowing 
For the working with digital images in an interactively 
window based user system a pyramid was constructed 
(Fig. 3.3.1). It represents a multiresolution structure of 
the originalimage (Ackermann, 1991; Rosenfeld, 1984). 
This concept allows to display the hole image of a lower 
resolution in an overview-window. In this window it is 
possible to select any region by zooming parts in a