Curvature Diagram
You can access this tool from the following:
Ribbon: Geometry > Regression > Curvature Diagram
Commands display a diagram representing curvature along the path of regression points. The horizontal axis represents stationing along the alignment. The vertical axis indicates 1/radius.
The purpose of the curvature diagram is to help you distinguish the arcs, spirals, and tangent sections in an alignment, based on the regression data. This command operates on raw regression data; you do not need to perform any regression analysis before running this command.
The curvature at any given regression point is determined by fitting an arc through that point and the previous and next regression points (a three-point arc). The radius of the computed arc is then associated with the given regression point.
As elements are created and added to the regression complex, the point representations in the curvature diagram are updated to reflect the new element created at the point location (different color for curves and lines).
Curvature Dialog Option
| Parameters | Description |
|---|---|
| Remove Outliers | This removes the statistical outliers, spikes, in the curvature diagram. The points are not removed from the raw regression data and not displayed in the curvature diagram. If you see spikes in the diagram use this option to hide problematic data. |
| Standard Deviation Multiplier |
Defines the boundary for removal. x 1.5 = Most aggressive. Removes values that are more than 1.5 standard deviation away from the mean. This will remove most number of points. x 3.0 = Moderate. Removes values that are more than 3.0 standard deviation away from the mean. This will remove a moderate number of points. x 4.5 = Least aggressive. Removes values that are more than 4.5 standard deviation away from the mean. This will remove least number of points. |
This tool displays a diagram representing curvature along the path of regression points in a horizontal alignment. While regression analysis can be done directly on the regression line, a curvature diagram makes it easier to identify curves, tangents and spirals. This tool operates on raw regression line; you do not need to perform any regression analysis before running this tool.
The horizontal axis represents stationing along the alignment. The vertical axis represents deflection of each point relative to its neighboring points. Raw vertical values are calculated as follows.
After finding the raw values, a rolling average calculation is applied to smooth out the fluctuations and obtain the final values.
The absolute value of the vertical does not provide much information about the geometry. It is the relative value of the points that represents the curvature. In the diagram points closer to horizontal axis have low deflection values, which means these points are on a tangent line. Points that are away from horizontal axis represents curves. Transition zones, that is the deflection of the points is increasing or decreasing, represents transition curves, spirals. The sign of the vertical value is negative for left-hand curves and positive for right-hand curves.
