The Information Overlaid Toolkit: ; Referance Manual Edition 2.2, for Information Overlaid Version 2.3; 25th October 2002
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Chapter 6. ? Scales

Scales are objects which convert between sets of coordinates. The standard applet understands only one kind of scale, linear. Special purpose versions of the applet for mapping may include others to handle different map projections.

There is currently no library of JavaScript related to scales themselves. Rather, the applet creates three scales which it uses internally, for instance to position markers.

? Scale Types

Some calls and applet parameters must be told which of these scales to use:

Table 6-1. Scale Types

scaledescription
screenThe position in pixels on the screen.
imageThe position in pixels on the image being displayed. This may differ from screen coordinates if the imag has been scaled to fit.
worldReal-world coordinates. If you specify the area which an image represents in the real world (for instance if it is a map or floorplan), this scale can be used to, for instance, place markers at known real-world coordinates.
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? Applet Features, Markers, Hotspots, ScalesUp? Markers