This command will sample a group of
points by screen selection or point number range, and then compute
the best fitting line by least squares. There are options to best
fit with nothing held (None), to best fit by holding a point, and
to best fit by holding a bearing. All three options are shown below
in the graphic. When holding a point, you are prompted to enter the
weight for the point. In this example, a weight of 1000 caused the
line to pass to within 0.025 of point 111. With a weight of 5000,
the line passed to within 0.005 of point 111. Increase the weight
accordingly to obtain the desired precision. When holding a bearing
such as N45E, you are prompted to enter the bearing in the form
QDD.MMSS (e.g. 145.0000 or just 145). The program generates a
standard report. The residual for each point is the perpendicular
distance from the point to the best-fit line.
After specifying the points, the
program calculates the best-fit line and shows the results in the
dialog show here. You can toggle each point for whether to include
in the calculations. Points with Process set to No and not used for
calculating the line but are still included in the report of
residuals. Use the Remove button to remove a point both from
calculation and reporting.
The Create Two Parallel Lines option
applies when the points are for two line that are meant to be
parallel such as a right-of-way. The program takes input for the
distance between these two lines and then automatically sorts the
points between the two lines, reports the residuals for the two
lines and draws the two lines.
Select points from screen,
group or by point number [<Screen>/Group/Number]?
S
Select Carlson Software Points.
Select objects: pick the five points
Point
numbers (Enter to continue): press Enter
Parameter to hold [<None>/Point/Bearing]: P
Enter point number to hold:111
Enter weight for
point: 5000
Sample Report:
Best Fit Line By Least Squares
Holding point 111: (5227.721,5149.482)
Coordinate File> c:\data\interval.crd
Source Coordinates
Point# Northing Easting Residual
109 5103.542 5182.098 10.050
110 5114.634 5191.928 6.921
111 5149.482 5227.721 0.005
112 5178.703 5268.237 0.400
113 5201.666 5312.602 8.129
Residuals Standard Deviation: 6.559
Bearing: N 53°44'07" E
Distance: 163.266
Pulldown Menu Location: COGO
Keyboard Command: bfitlinelq
Prerequisite: Group
of points to sample