About Exact Measurement Computation

The Measure command permits an exact measure on geometric entities. The measure computation is based on the geometric modeler which specifies a tolerance value for creating geometric objects. This tolerance value must be taken into account when performing exact measurements as it greatly impacts the measure results.

This section provides detailed information about the exact measurement computation.

This page discusses:

Understanding the Tolerance Value

The tolerance value is the threshold value under which two geometric points coincide. In other words, it is the lowest admissible length under which a geometric object can be created.

This tolerance value specifies the minimum length for a valid object. It is set to 10^-3 unit. As the unit is expressed in mm, lines with length shorter than 1micro-m are not valid. For example, curves or edges whose length is below the tolerance value are not created.

The tolerance value specified by the geometric modeler manages:

  • coincidence issues

    When the distance value between two geometric points is below the tolerance value, the two points coincide.

  • impacts on Boolean operators

    An example is when edges with a length value below the tolerance value cannot be created.

The figure below shows the impact of the tolerance value at creation time:

On the top row, if D is superior to the tolerance value, a new face is created. On the bottom row, if D is inferior to the tolerance value, the face is gripped and is separated into two distinct faces.



Impact of the Tolerance Value on the Measure Between Computation in Exact Mode

It is not possible to guarantee the validity of measure results when they are below the tolerance value specified by the geometric modeler (0.001mm).

Impact of the Tolerance Value on Measure Item Computation in Exact Mode

Surfaces, arcs, curves and lines are created with respect to the tolerance value specified by the geometric modeler.

The measure item capability may detect that the geometry corresponds to an arc when the curvature radius changes within the limits of the tolerance value specified by the geometric modeler.



  • If a < tolerance value is specified by the geometric modeler, this entity is considered as a line.

    The appearance of the measure item or measure between (second selection) cursor then changes to a line, indicating that a line is selected:

    or . And the selection boxes of the Measure panel indicates the measured entity type as a line.
  • If a > tolerance value is specified by the geometric modeler, this entity is considered as an arc.

    The appearance of the measure Item or measure between (second selection) cursor then changes to a circle, indicating that a circle is selected:

    or . And the selection boxes of the Measure panel indicates the measured entity type as an arc.

Selective Loading of the Representation to Authoring Mode

When you select the Exact calculation mode for the measurement, the system automatically loads the representation in the authoring mode to compute the exact results of measurement. However, the system checks for the availability of the authoring data to perform the operation.

Note: In case the design mode is unavailable for the selected geometry, a message appears to inform you.