MX Triangulation Void Creation

Creating a void in a triangulation is something you may have a need to do from time to time, for example at locations where there are ponds in a survey.

This can be achieved by using a string called a PBRK string, the PBRK string is a point string that will be excluded from the subsequent triangualtion analysis. There can only be one PBRK string per model however the PBRK string can have as many points as you require for the model.

The example below runs through the process of creating a void for the 2 pond locations (blue strings) at the top and bottom of the image below.

If you create a triangulation of this model, as shown below, you will see that the triangulation is created within these strings.

You will need to create the PBRK string with points within the triangles you want removed from the triangulation to create the void. You may not always need a PBRK string point within every triangle however this process errs on the side of caution to ensure that they are excluded.

A quick process for creating a PBRK string is by using the Create a String Dynamically tool (MX>Modify>Edit a String> Create a String Dynamically).

I’ve added points at the two pond locations as shown below and saved the string to the survey model as a PBRK string, it is advised to set the levels of the string as null as shown on the save panel.

When I recreate the triangulation of the survey model it now has voids in at the pond locations as shown below.

Any questions, please add comments to this post, or drop me a mail at jason.walsh@bentley.com or call us on 0808 1019246.