International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004 nic 
  
Analogue Maps 
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Figure 1 Functions of maps at played in different stages (Li, 2002; Li and Kraak, 2002) [. 
3. ADDITION OF GRAPHIC VARIABLES FOR WEB in. 
MAPS 
Table 2 lists the sets of variables in use at such different 
stages as follows: 
e Visual variables: Size, shape, orientation, hue, 
saturation, intensity, position, texture, arrangement 
(Bertin, 1983; Robinson et al., 1995; Jiang, 1996); 
e Dynamic variables: duration, rate of change, order; = 
, e Exploration acts: Drag, pan, zoom, click, blink, 
highlight (Jiang, 1996); 
To make maps possess such roles, some kind of visual 
variables need to be employed. With web as a medium, the 
traditional cartographic variables as proposed by Bertin (1983) 
(Figure 2a) have been extended popularly. At digital map stage 
theoretically, some variables particular to screen display (Kraak 
and Brown, 2001) may have been in use. At visualisation, e Screen variables: Blur, focus, transparency (Kraak | 
dynamic variables (DiBiase et al, 1992) have been introduced and Brown, 2001); and 
and exploratory acts (Jiang, 1996) (Figure 2b) arc widely used e Web variables: Browse, plug in. 
for visual analysis. At a stage of web-based visualisation, more 
exploratory acts are in use, particularly the hyperlink and plug- 
  
Table 2 Variables in use at different stage of development (Li, 2002; Li and Kraak, 2002) 
  
  
Map form 
Variables in use 
  
Paper Maps 
Visual variables 
  
Digital maps 
Visual variables 
Screen variables 
  
Cartographic visualisation 
Visual variables 
Screen variables 
Dynamic variables 
Exploration acts 
  
Web-based visualisation 
  
  
Visual variables 
  
Screen variables 
  
Dynamic variables 
  
Exploration acts 
| Web variables 
  
  
  
  
   
   
  
  
(a) Visual variables for communication 
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(b) Exploratory acts for analysis 
Figure 2 Variables for cartographic visualisation (Jiang, 1996)