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KB10730 - Zoom, ZoomEx, and Scale properties.

  1. Zoom unit is one if one map unit is represented by one pixel. Using Zoom, therefore, is device dependent.
  2. ZoomEx unit is one if one map unit represents one twip (1/1440 of inch) on the screen. Using ZoomEx, therefore, is device independent, but its use is obsolete in favor of Scale.
  3. Scale unit is one when the screen presents the map as 1:1 (one centimeter on screen is one centimeter on the map). Be aware that screen PPI (points per inch) is used to perform this calculation and, therefore, calculation on screen can be slightly off. However, calculations for printer (which present real PPI) are accurate because using Scale is device independent. Using Scale is the recommended method, but requires a proper Coordinate System setup for the map.
  4. ScaleAsText ​presents one pixel to equal a common text representation like "1:1000000".
Created: November 27, 2006, Modified: June 25, 2019