Tip of the Week #45 - Creating Arcs with Polylines

By Matt McLean posted 06-15-2018 14:51


This weeks’ tip of the week is for the drafting users in the audience. It’s a little known shortcut for making arcs from polylines. (Note that this will not work with linestrings)


Start by drawing a polyline. It can be as simple as one line or a complex feature.




Next, in File > Options, or from the Quick Access Toolbar.




Ensure the “Turn on CAD grips” checkbox is selected.


This toggles end and midpoint grips for straight lines and curves.



With the rightmost polyline selected, double click on the midpoint grip, represented by a triangle. (End points of polylines are represented by squares)



The polyline changes to an arc, wow!


By clicking and dragging the midpoint grip, the radius of the arc can be adjusted.



Adjacent polylines can be adjusted individually, to create and replicate complex real world arc features.



The polyline arcs cannot be made to have a diameter larger than the distance between the two end points.

A useful application of this is the ability to draft circles with two points at opposite sides of the circle. For example, take points 100 and 101 below.



Draw a polyline between the points, double click the midpoint grip to convert the polyline to an arc, and drag it the maximum distance either up or down.



This creates a semi-circle with a diameter the distance between points 100 and 101.

Repeat the process, except this time drag the midpoint of the arc the other direction, and a circle is formed.



And voila! A circle from two points. Break time? Break time.


TBC - Field to Finish with Confidence.