Accuracy of Rhino model


(Mbathala) #1

I would like to understand the model tolerance info of Rhino. What is the default accuracy type of Rhino - Relative or Absolute?
How to check whether a Rhino model uses Relative or Absolute accuracy using openNURBS API?

Thanks
Mallikarjuna Bathala.


(Dale Fugier) #2

Hi @mbathala1,

This from the openNURBS source:

ON_3dmUnitsAndTolerances::ON_3dmUnitsAndTolerances()
: m_unit_system(ON::millimeters)
, m_absolute_tolerance(0.001)
, m_angle_tolerance(ON_PI/180.0)
, m_relative_tolerance(0.01)
, m_distance_display_mode(ON::decimal)
, m_distance_display_precision(3)
{
  // Do not set m_unit_system.m_custom_unit_name here.
  // Doing so creates a heap allocation in the construction of
  // ON_3dmUnitsAndTolerances::DefaultValue
  // and doesn't make much sense in any case.
}

Of course, each 3dm file can be set to whatever tolerances the user chooses. Most of the time, the template file used to create the model dictates these values.

I don’t understand this question. The tolerance values are not dynamic. That is, changing the tolerance values does not cause existing geometry to be re-evaluated or re-computed. Rather, these values are used during the modeling process.

– Dale