436 
Changes 
in terrain 
Natural 
phenomena 
Human 
activities 
-Errosion 
-Desertification 
-Climatic change 
- Disasters 
- Other 
-Physical 
-Administrative 
-Legal 
-Other 
Pragmatic_ 
view 
Dynamic_ 
view 
—Relevant 
-Partly relevant 
Non relevant 
_Gradual 
changes 
Sudden 
changes 
- Fast 
- Medium 
- Slow 
Very slow 
- Disasters 
-Polytical 
- Predictability- 
Legal 
- Other 
Predictable (deterministic processes) 
-Partly predictable (stochastic processes) 
-Non predictable (e.g.disasters) 
Figure 5: Issues related to changes in terrain. 
Information Flow 
Figure 6 shows the flow of the semantic information. The corresponding 
operations are involved in all stages of the process and several of them 
(indexed by M) coincide with operations in the geometric data flow (fig. 10) 
► Input8 
Preparation 
Mensuration 
►Editing and 
generalisa 
tion 
Plotting 
Figure 6: Flow of semantic information.