This command processes a group of
points to compute the best fitting centerline by least squares. The
points can be input from Carlson points or from vertices of a
polyline. For points input, the points can be selected by screen
selection or point number range. Each line segment in the
centerline is calculated by the best-fit line method and each arc
segment is calculated by the best-fit arc method.
In the process options dialog, the
Snap Tolerance is the max offset from the point to the line or arc
segment in order to be counted as part of that segment. The
Polyline Layer is used for the output polyline. The Max Radius
controls the maximum radius for arc segments that the program will
fit to the data. The Create Tangents Only option skips the step of
calculating the best-fit arcs and outputs only the lines. Arcs can
be added later using routines like Fit Curve in the Input-Edit
Centerline command. The Make Curves Tangential option fits the line
and arc segments to be tangential. The Min Points For Arc setting
controls how many points are required to calculate an arc. If this
number is low that makes is more likely to create an arc where some
points vary from linear but there really isn't meant to be an arc.
If this number is high that makes is more possible to miss creating
an arc in case the arc only has a few points on it.
The residual
for each point is the perpendicular distance from the point to the
best-fit centerline. The results are shown in a dialog and you can
toggle each point for whether to include in the calculations.
Points that are toggled off are not used for calculating the
centerline but are still used in the residual report. The Remove
function removes the point from both calculation and residual
reporting.
Input existing data from points or polyline
[<Points>/Line]? press Enter
Select points from screen or by point number
[<Screen>/Number]? S
Select Carlson Software Points.
Select objects: pick the centerline points
Pulldown Menu Location: COGO
Keyboard Command: bestcl
Prerequisite: Group of
points or a polyline to sample