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 Centerline Editor command. The Make Curves
Tangential option fits the line and arc segments to be
tangential. The Remove Outliers applies when the input data
is noisy. This option will remove points that seem too far off the
centerline to improve the centerline match with the remaining
point. 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
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