de PRIMITIVE nodes lines surfaces TIN 
  
S node name straight closed triangles 
coordinates curved polygon for DTM 
(x, v, [2]) arc with 1 
nel reference lists circle exterior references 
S dynamic node info reference and several to adjacent 
standard deviation list interior triangles 
J multiple measure- boundaries 
ments (quality, 
accuracy) 
nd attributes PRAT PRAT PRAT 
dh CAT CAT 
FEATURE - one or more geometric primitives, conforming to one 
topologic type (node, line, spaghetti, surface). 
- belongs to a single feature class 
  
  
  
  
  
  
  
une attributes DRAT 
js COMPLEX - defines an entity of one or more features 
FEATURE - belongs to a single feature class 
di attributes DRAT 
FEATURE - defines logical organisation of data 
CLASS - identifies topologic checks and topographic checks be- 
tween features 
- consistent graphic output (graphic transform) 
PARTITION - working subset of a project 
- selected graphic representation (graphic transform) 
- selected feature classes (themes) 
í PROJECT - definitive version of the database 
- defining/modifying feature classifications, attributes, 
d themes, topographic/topologic checks 
- checks for merging partitions 
- restrictions on operator-group access 
Fig. 1: SYSTEM 9 data model 
)po- a) Primitives 
age Data capture starts with the simplest items, the primitives. Primitives 
can be either nodes (point information), lines, surfaces or triangles. 
lad A node is stored as a set of X, Y, [Z] coordinates. It can have a 
unique name, information about standard deviation, multiple measure- 
ments and source of the information. Dynamic nodes are also possible. 
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