You can access this dialog from the following:
- Ribbon:
Geometry > Create Regression > Regression Line from
Line
Creates regression line from a 3D LineStrings. Vertical
information from the 3D LineStrings will be added to the new regression line as
vertical geometry.
Regression Line
from Line dialog
Note: This tool works for
a linestring live in the file but not for a linestring in an attached reference
file