preserveAspectRatio="xMidYMid meet"> 

viewBox =  leftupX  rightdownY viewBox.width viewbox.height  

viewBox.width = rightdownX leftupX   

viewbox.height = rightdownY leftupY 

map scale = Screen.width(mm)/ viewBox.width(m) 

Listing 10:

 Formulary to calculate the map scale 

The principle of this transformation is the coordinates system transformation from the 

view box coordinates system to a geocoded coordinates system. It is a 2 dimensional 

similarity  transformation  (2D  Helmert).  There  are  four  transformation  parameters  in 

this  transformation.  X  shift,  Y  shift,  scale  factor  and  one  rotation  parameter  (see 

Figure 13).   

Y 

X 

X 

Y 

SVG view box 

Fig. 13: 

Coordinates transformed from SVG view box coordinate system to a geocoded 

coordinate system. 

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