Tip of the Week #11 – Taking Control of your Surface Creation - Breakline Tolerance

By Boris Skopljak posted 05-25-2017 10:12


Surface creation in TBC is definitely one of the software gems. TBC offers a lot of flexibility with appearance and creation of your surfaces. This week’s tip helps understand some of the controls you have over how your breaklines are triangulated. Here is how you might resolve the number of nodes/chords along the surface breaklines.

In Project Settings > Computations > Surface > Breakline Approximation Parameters there is a setting for Hz and Vt tolerance.

Here is a surface created using our Processing Feature Code Tutorial.


Now, let’s change the project settings and put e.g. 10m for the Hz tolerance.

And the result is a less sampled breakline with fewer nodes/triangles along the breakline.

Internally, what is happening is that there is a concept of mid-ordinate point to compute the distance of the node between the chord and the arc along the curve as illustrated by the graphics below.


We hope you find this tip useful regardless if you are going to be exporting surface or breaklines to other products doing contouring for your base map creation within TBC.




11-28-2017 14:59

Much appreciated thanks for the tip!


On Tue, Nov 28, 2017 at 2:56 PM, <>

11-28-2017 13:55

Only way I've been able to get this to work is change the surface properties from "Rebuild method" to By User. Unfortunately if you need to edit anything in the surface you'll have to go back and redo your "Swap Triangles" again.

11-27-2017 15:55

When I go through and get my triangles all swapped around like I want them, they have a tendency of going back to how they were before I started adjusting them.  Any advise on making them stay put?  They tend to play hell on our machine controls when they don't cooperate.  Thanks.