Null Measurement

The Null Measurement functions exactly as the Measurement tool except that the Measurements created are immediately removed as soon as you lift your finger. You might want to do this if you want to measure things on your model without actually altering the model. Like the Measurement tool, you’ll need to define a Reference Length first. Here’s an example:

Reference Length

The Reference Length tool allows you to specify a unit length that can be used by the Measurement tool for measurement. The segment is constructed in the same way that a Line Segment is constructed. When the construction is completed, a dialog box will be presented asking you to specify the length of the segment. The default is 1 but you can enter any positive value that you want. You can have more than one Reference Length. [Read More]


The Measurement tool is used to measure distances on the screen using a Reference Length as its basis. The construction is the same as for a Line Segment. If no Reference Length has been constructed yet the Measurement has no way of measuring the distance so the construction will be cancelled. Note that the measurement is accurate at the scale of its construction. If the Measurement path is rescaled, the value will be no longer be valid. [Read More]

Measurement Sum

The Measurement Sum tool is used to find the sum of all the Measurements in a selected region. The region can be selected using either a rectangular area or a circular area. The sum will only include Measurements that correspond to the currently selected Reference Length, and the sum itself will simply be a Text Path centered in the selected region. You can move the text anywhere you like after construction using one of the Transformation tools such as the Move tool. [Read More]

Switch Reference Length

The Switch Reference Length tool is used to change the Reference Length that is used by the Measurement tool. You can have more than one Reference Length. The currently selected one will have an asterisk(*) besides its number, and that length will be used for measurements made with the Measurement tool and Null Measurement tool. Simply tap another Reference Length segment using this tool to select it. Here’s an example: [Read More]