undary 
(1) 
Euler- 
valid in 
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iumans 
erators 
model. 
, mekr, 
ter "m" 
e other 
istance 
ex. 
sers of 
hidden 
erators 
jh-level 
from a 
of face 
undary 
bes the 
ate the 
ws the 
; steps 
vs two- 
plogical 
1988). 
rouped 
! done 
hat the 
tructed 
| is also 
logical 
j model 
actable 
he goal 
. Semi- 
n work 
t in the 
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can be 
tives in 
. In the 
of lines. 
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atching 
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of least 
t space 
(1988), 
iples of 
ibed in 
  
  
  
  
Ed 
DU Tm 
C2 (2 
ce uA 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
/ N 
e 
\ ) 
NS A 
MVFS MEV, MEV, MEV 
MEF 
MEV KEF 
MEF, MEF, MEF 
MEV KEF, KEF 
MEF, MEF, MEF 
  
  
  
  
  
  
  
  
  
MEV, MEV, MEV, MEV MEF, MEF, MEF, MEF 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
MEV KEF 
KEV 
MEV KEF 
KEV 
  
Figure 1. Construction of a boundary representation model. Upper set: sequence of editing steps used to create a geometric 
model. Lower set: Euler-operators that correspond to the editing steps shown in the upper set; plane model graphs illustrate 
the topology of the model. 
215 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996