Datasheet

creaTing curves
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cr e a t e be s t fit Pa r a b o l a co m m a n d
The Create Parabola command under the Create Best Fit Entities option works in a similar way
to the line and arc commands just described. This command is most useful when you have a
Triangulated Irregular Network (also known as TIN) sampled or surveyed road information
and you’d like to replicate true vertical curves for your design information.
After you select this command, the Parabola By Best Fit dialog appears (see Figure 1.42).
You can select inputs from entities (such as lines, arcs, polylines, or profile objects) or by pick-
ing on screen. The command then draws a best-fit parabola on the basis of this information. In
Figure 1.43, the shots were represented by AutoCAD points; more points were added by select-
ing the By Clicking On The Screen option and using the Node osnap to pick each point.
Once you’ve selected your points, a Panorama window appears, showing information about
each point you chose. Also note the information in the right pane regarding K-value, curve
length, grades, and so forth.
In this interface (shown in Figure 1.44), you can optimize your K-value, length, and other val-
ues by adding more points, selecting the check box in the Pass Through column to force one of
your points on the line, or adjusting the value under the Weight column.
Figure 1.42
The Parabola By
Best Fit dialog
Figure 1.43
The best-fit pre-
view line changes
as more points are
picked.
Figure 1.44
The Panorama
window lets you
make adjustments
to your best-fit
parabola.
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