Point Size at Map Scale Calculator


Cartographic symbol sizes in points are often confusing when dealing with different map scales and symbols. Symbol sizes in ArcGIS are specified in points (Points are a standard graphic measurement unit equal to 1/72 of and inch). Symbols are drawn at their point size with respect to a scale (typically scale is controlled for a map by setting a reference scale). This sample provides two simple calculations on one form to help move between points, map units, and map scales.

The first section converts point size at one scale to point size at another scale. This conversion allows you to convert a point size at one scale to point size at another scale and maintain the same geographic size. For instance, 8 point text at a scale of 1:1200 is the same geographic height as 16 point text at 1:2400. A common use for this conversion is to model multiple scales of text in one annotation feature class. Since annotation feature classes only have one scale, modeling different scales of text will require this calculation.

The second section of this calculator sample converts geographic units to points at a specific scale. Cartographic specifications often note symbol and text sizes in map units. Since ArcGIS symbols are specified in points, calculation can be difficult. This sample allows you to simply specify the size in the map units and the reference scale of the map. The correct point size is then calculated. Note: Font sizes refer to the size of the text block body, not the size of any specific character(s). Very few fonts contain characters that occupy the entire height of the block. Therefore, text and character based symbols will most likely not draw at the exact geographic size.

ArcView: VB6

Platforms: Windows

Minimum ArcGIS Release: 9.0

How to use:
  1. Run the PointSizeCalculator.exe to launch the sample.
  2. Enter the values for the conversion you wish to perform and press the appropriate Convert button.

Download the VB6 files
frmConversion.frm Form containing the GUI and main conversion code for this sample
PointSizeCalculator.vbp The Visual Basic project for this sample.
PointSizeCalculator.exe Compiled Executable.

Download the files for all languages

Key Libraries: System
Key CoClasses:UnitConverter
Key Interfaces: IUnitConverter
Key Members:IUnitConverter:ConvertUnits