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• double precision floating point numbers relating to coordinates in the real world
• integers relating to units on the output device

This approach provides the highest level of flexibility for scaling, coupled with the highest possible display update speed for repaints, panning, and animation.

A regeneration operation is performed as required to calculate the device unit coordinates from the real coordinates. For very complex drawings this can take a few seconds, so special techniques are employed to regenerate what will actually be within the display window first, followed by what will be outside the window.

TGS uses a comprehensive 4 tiered coordinate scaling system, and uses 3x3 matrices to perform the conversions between the different coordinate systems.

This scaling system allows the application program to use one or more real coordinate systems which are in context with the graphics being processed. eg. mapping info can be defined in terms of the map grid in use. The scaling system then allows for page placement, special print operations such as multipage printing, and translation to the coordinate system required by the output device.

Control primitives may be placed throughout the primitive table to dynamically change the scaling and placement of graphics throughout a drawing.

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