You can access this dialog from the following:

• Ribbon: OpenRail Modeling > Regression.

This tool is used to make an initial best guess of all elements (line, arcs). The software computes the existing versine from the regression line then determines the approximate location of linear elements and arcs. Created elements are not combined into a complex geometry.

Tool works only on the profile view (regression line).

Calculation algorithm works as follows:

1. Calculate the versine value of all the points.
2. Assign a value of 0 for any versine value lower than the Tolerance. This helps reducing the noise in the linear points.
3. Group the points based on their updated versine value. Any point that has high versine value is a candidate for arc placement. Any value that has zero versine is a candidate for line placement.
4. Discard any group that has a length shorter than the Minimum Element Length. This ensures no elements that are shorter than the defined value will be created.
5. Create arcs and lines.
6. Add vertical geometry element rules.