phic procedures (rotations, connection of parts etc.). This 
structure often is referred to as a "wire model" of the sur- 
face. Or one stores the surface patches, which e. g. is use- 
ful for graphic display including shading and which may re- 
sult from an automatic segmentation of the image. Both 
representations may be combined. Especially the patch model 
could be based on the wire model. 
The wire model seems to be appropriate also in our appli- 
cation. As the measuring procedure is a sequential one, re- 
ferring to the photogrammetric model as a unit, the line- 
-type scanning of the measuring head in a natural way leads 
to a line-type description of the surface. Of course the 
lines may be made dense enough to enable a sufficiently 
accurate approximation of the whole surface. Only a parallel 
measuring process would lead to an area - type description, 
6. 2. based on a triangulation of an irregular point 
pattern. In our case both types of representation can be 
combined (cf. figure 1): The line-type description replaces 
the levels 3 and 4 in the hierarchy (cf. table 1) and can be 
used for representing standard profiling,  gridding or con- 
touring (cf. figure la, b, c). The results of the lower le- 
vels O - 2 are descriptions of the arcs in the graph and may 
contain either arcs of the graph, i. e. sections of profiles 
(fig. 1b) or contour lines (fig. lc) measured with LSM or 
they may contain local patches of irregulary distributed 
points (fig. 1e) measured with FBM. 
Figure 1: Influence of measurement procedure 
on surface representation 
a., b., c. intersection of planes with surface 
density along measuring path arbitrary 
d. ,. 9. irregularily distributed points 
a. profiling d. irregular point pattern 
b. gridding (driven by data, image interpretation) 
c. contouring e. combination of a. and d. 
upper level: profiling 
lower level: irregular point pattern 
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