4 Progressive Techniques
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p 2
p 6
p 10
p 5
p 8
p 0
p 12
Region 2
Region 1
Region 0
p 13
p 14
p 15
l 1
l 0
l 2
l 3
p 17
p 16
p 1
p 3 p 4
p 9
p 11
p 2
p6
p 10
p 5
p p
7 8
p 0
p 12
Region 2
Region 1
Region 0
p 13
p 14
p 15
l 1
l 0
l 2
l 3
p 17
p 16
p 5
p 8
p 0
p 12
Region 2
Region 0
p 15
l 1
l 3
l 0
p 16
map 0
p 14
p 13
Region 1
p 2
p 10
p 6
l 1
p 1
p 3 p 4
p 7
p 9
p 11
l 1
p 5
p 8
p 0
p 12
Region 2
Region 0
p 15
l 1
l 3
l 0
p 16
level 0
p 14
p 13
Region 1
map 1
map 2
level 1
level 2
Fig. 4.4. (Left) Sequence of simplified maps: map 0, map 1, map 2; (right) corresponding
representation levels stored in the data structure: level 0, level 1, level 2 (for simplicity vertical
links are not drawn here)
levels in the sequence available on the server to obtain the requested information.
Note that this approach decreases risk of information loss due to network failure: if a
network failure occurs during data transmission, users need request to re-download
a smaller file rather than the fully detailed map. This is particularly beneficial in
mobile environments where network connections are unreliable.