Computational Aspects: How Landmarks Can Be Observed, Stored, and Analysed - Landmarks: GIScience for Intelligent Services - page 139

Tabl e 5. 2 Deriving landmark salience for the 'Haas' building

Attractiveness
Measure Measure Property Value Significance Weight Total

s v is D 4=5 w v is D 1

Visual
Attraction

p v f 17400 1 1.8

p v sf 0.62 1

p v sd 0 0

p v c [21,24,38] 1

p vv 10600 1

Semantic
Attraction

p sec 1 1

s sem D 2=2 w sem D 1

p sem 1 1

Structural
Attraction

p stn - 0

s str D 0=2 w str D 1

p stb - 0

Example taken from [ 35 ]

Fig. 5.3 A landmark with low ( left ) and high ( right ) advance visibility; modified from [ 52 ]

are identifiable early on along a route are more useful than those that can only be
spotted at the very last moment. Figure 5.3 shows an example of a landmark with
low and high advance visibility.
Formally, advance visibility v is a measure of route coverage c and orientation
o of the landmark in question. Route coverage reflects how much of a landmark is
visible along the entering route segment when approaching the intersection where
it is located. The route coverage measure is calculated as the ratio between the part
covered by the landmark and the total length of the route segment, which is specified
by start and end point p s , p e . Orientation o measures the orientation of a landmark
towards the route. A landmark that is oriented in moving direction is easier to spot
than one that requires considerable head movement. Formally, orientation is defined
as the difference between façade orientation d f and route segment orientation d r ,
both in terms of cardinal directions.

v D c o (5.2)

j p i p e j
j p s p e j

c D

j d f d r j

180

o D