Contour It  (CI13)

The breakline from pt. x to pt. y intersects with the breakline from pt. a to pt. b.  Select Breaklines from the Edit menu and adjust the breaklines accordingly.

Your breakline file contains crossing breaklines, a condition that Contour It! does not allows.  Use the Edit > Breaklines routine to modify the offending breakline. 

A breakline is a line segment connecting any two points. Breaklines have the ability to modify the surface model by locally adjusting the triangulation.  By changing the triangles, the relationship between data points is changed.  This produces a different surface model and thus different contours. 

Breaklines are helpful for defining objects such as building slabs, and retaining walls, grade lines, roadbeds, ditches, canals, etc.

Breaklines permit: 

1.  Post processing to alter portions of the triangulation thus generating a more accurate surface model;        

2.  Control of the triangulation by specifying lines which triangle sides cannot cross.  Their use allows preservation of significant terrain features even though the lack of sufficient data may favor a different triangulation;

3.  Definition of ditches, roadways, terraces, etc. with a minimum of field data.

Specifying Breaklines                

When passing points from “Sight” Survey to Contour It!, you are given the opportunity to enter breaklines.  To specify a breakline, simply type in the point numbers of the beginning and ending points, separating the points with a comma.  You may also select breakline points visually by using “Sight” Survey’s  (GS) command. 

Sometimes you might have a breakline that changes direction a few times.   For example, imagine a three segment breakline snaking from point 1 to 2 to 3 to 4. 

Technically, a breakline is only one segment long.  To specify a multi-segment line, you must include each segment in the breakline string.  In this case, an entry of 1,2,3,4 would result in two breaklines: from 1 to 2; and from 3 to 4.  Each breakline must be represented by a pair of points.  To properly enter this three segment breakline, type 1,2,2,3,3,4.

Breakline Rules

1.  Each breakline is always defined by two points.

2.  A breakline cannot cross a border.

3.  A breakline cannot cross another breakline.

4.  A breakline cannot cross a data point.

Breaklines can be created either before of after triangulating the data file.  It is often better to create breaklines after the initial triangulation to avoid creating unnecessary breaklines.

© 2008 by Carlson Software, Inc.   Last modified November 18, 2008