National Exchange Format Digital Height Model-Program 
(DSFL - Format) (Intergraph "MODELER" } 
class code object code theme object type 
road system KG3 sideline of i13 DHM break L 
road 
unpaved way U21 break L 
parking U24 break L 
local road U27 break L 
path U 31 break L 
buildings & KG4 house - Ul - = 
constructions roofline 
greenhouse U31 = - 
fences KG5 hedge Ul - - 
land use U32 break L 
border 
area symbols KG6 | coniferous U12 spot p 
forest 
(symbol) 
Special ob- KG8 high voltage U33 Spot P 
jects line - base 
Table 2 Crossreference table for conversion of database data 
(T3-data) in the Danish National Format into objects 
of a height model 
(Pre.DOint, L...lino, 
By means of a simple analysis-function, 
"Built Query", one can query the data base 
  
Figure 6 Height model displayed by means 
of grey values. This represen- 
tation is used in quality con- 
trol. 
by Structured Query Language (SQL). For 
example, one can find and display the are- 
as for a certain slope range (see fis.7). 
With other ANALYST functions one can auto- 
matically derive the area or the perimeter 
of the slope polygons. Slope information 
can be overlapped with other area related 
=oe 000% used) 
information, for example the soil type. 
The result of such a spatial query can be 
a new map of polygons which displays the 
risk for soil erosivity. Soil erosivity 
maps are used in landmanagement. A similar 
application is described in (Sigle, 1991). 
  
Figure 7 Polygons for the slope range 
09 - 2° together with contours. 
In figure 8 the generation of a soil ero- 
sivity map is presented schematically. A 
new object (soil erosivity) and a new 
attribute (potential soil erosivity risk 
(PSER)) are synthesized. Spatial operators 
such as "overlap", "meet", "within dis- 
tance", "contain", "touches", etc. can be 
used to create new objects. Attributes can