DETERMINATION OF THE FLATNESS OF SURFACES 
USING A MULTIPLEX-PROJECTOR 
Gunnar Simonsson 
Department of Photogrammetry, Stockholm 
A rapid method for determining the deviation 
from flatness of surfaces has been developed 
and proved in practice at the Department of 
Photogrammetry, at the Royal Institute of 
Technology in Stockholm, Sweden. 
The devlopment of the method was initiated by 
a request from the Volvo Foundry in Arvika, 
Sweden. The company was having problems with 
the flatness of the surfaces of moulds and 
wanted a rapid method to weed out the worst 
Specimens and also to get an indication of the 
deviation from flatness. 
The principle of the method is as follows: 
A horizontal plane line-grid, the same size 
as the mould surface (1.6 x l m) was photo- 
graphed using a Multiplex-projector as a 
camera, as shown in Figure 1l. A photographic 
  
Fig 1 
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