Retriangulate TIN Surface - Add Surface TIN Lines from selected CogoPoints

Dear all,

I am trying to develop a Dynamo script to automatically retriangulate a TIN surface between some added COGO-POINTS in an specific order. In other words, in an existing TIN SURFACE, where some COGO POINTS were added, using the AddSurfaceLine command between them in a logical way.

I added an image to make it more comprehensible.

In a first moment, this could lead to a chaotic triangulation if the points were not sorted before introduced to the triangulation process.

In my case I am trying to add north-south lines between points which have the same X coordinate (easting). That’s why my first step was to develop an script to create a List of the cogo points involved in the process and sort them by their coordinates X (easting) - image attached. Each pair of points included in the list [0,1], [2,3], [4,5],… would be in this example the end points of the new lines.

This part of the script can be find in the next image.

Unfortunately once the list is created and sorted, I can’t find any node in the library to edit a surface and add lines between introduced points.

Any idea of how to approach it?

Much appreciated,

Hi , as an idea
Can you make surfaces from groups? then add it to the base surface from copy surface

Hi there!

The problem with this metod would be that lines would not be created in an specific way.


Hi again @hosneyalaa !

I had a look at the post (which I found very interesting btw) but I could not think of a way to link it with the retriangulation script.

Do you mean that the solution may be to create a python script?

I will be on sites visits for the a few days, apologies if I take some time to reply.

Much appreciated

I can’t help you well You did not share a dynamo file or an AutoCAD drawing, for example
In any case Can you add a rectangle SurfaceBreakline

Hi @hosneyalaa !

I am back from site surveys, sorry for the delay.

Attached you can find an example of what I am trying to do:

  • 01_EXISTING_SURFACE: The TIN surface is defined by an existing group of points 01_SUP_DYN.
    An additional and independent group of points is added to the surface 02_MT_DYN.
    As you can see in a first instance, the TIN surface triangulates the closests points automatically.

My goal is too create an script to triangulate the group of points 02_MT_DYN in the surface between them in a certain logic.
With which logic? Creating E-W or N-S axis. In this case N-S (blue lines).

For this purpose, I created an script to create a list of points from the COGO Points Group (02_MT_DYN) and sorting them by coordinate X (in order to have the N-S axis).

The problem I am facing now is that I can’t find any node in the library to edit the surface and triangulate them.

I hope its more comprehensible.

Much appreciated,
2022_09_29_DYN_TRIANG.dwg (899.8 KB)
00_MT_TIN_ADDLINE_v1.dyn (29.5 KB)

According to my understanding
Drawing lines on the surface is according to height, not according to location

If you want to connect the POINTS by location
Arrange the points without height and connect them WITHOUT USING surface