Create Internal Linestring Boundary

Is it possible to create an internal boundary line string along the edges of the existing triangle to create a void in the surface? As I need to merge this surface with several other surfaces

The surface is a .12daz file with an internal voidtin 15th detail survey.7z (162.9 KB)
I cant use the 12 surfaces as it seems to bring in some NUL values, so it need rebuilding

My current process is
Explode the 12d surface - drape line command is greyed out
Build new surface
Trim Surface Edge
Create External Boundary
Trace the internal boundary

It would be good if we had a command to track the edges internal & External before the surface gets built

Can you share the file - I would likely use the Explode Surface command - I would like to try out a couple of things to get you the answer


Hi Alan

Managed to explode the surface but had to draw the inner boundary

Here the link to the original 12d file / surface


Hi Alan

Also one other problem i have found with a 12 d surface is that your unable to merge two surfaces together? Is this a know issue?

My work around is to explode each surface and rebuild it, was wonder if you’ve come across this issue with XML surface.


I looked at the file and the following applies

  1. The surface is a TIN model and the TIN has hidden triangles in the void area and actually around the outside of the surface as well. If you change the surface color to RGB 100,101,102 that will show you the hidden triangles.

  2. The surface has Drape Lines in it (in the plan view if you turn off all the Plan View options in the surface properties but leave the drapelines turned on) you can see them as shown below here. Our Explode Surface command should allow you to explode out just the Drapelines, but for some reason on this surface it is grayed out - I have Peter looking at this as we speak … - If that worked (and it will by later today) you could just extract the Drapelines using Explode Surface to get the boundary line that you need

  3. Because of (2) I used the Explode surface command to explode the surface to create the breaklines (TIN Sides). I then select all the TIN Sides and set the property on those from Sharp to Sharp and Texture Boundary. I then make a surface out of the TIN Sides and then assign a Null Texture to the heart shaped hole area. (Use Surface Texture command, call the texture Null, and do not select a material / texture and click in the hole - this nulls out the triangles all the way out to the first TIN sides around the area.

  4. If you need that boundary around the hole, it is now a drape Line that you can explode, or you can use Track Region Outline command to find the boundary

We will fix the Drape Line extraction on this surface (at least find out what is going wrong there - as it maybe something the Australian guys are doing incorrectly) and let you know.

Drape Lines are lines that are created around Texture or Site Improvement Areas as they are assigned / created - they are also lines that we set the Sharp and Texture boundary property on (vs Sharp only)

Breaklines are all lines that are used to make the surface that have the Sharp Property or Soft Property on them and do not act as a Site Improvement or a Texture area.

When TBC creates a surface from Points and Lines we have full control over those elements, when a file is imported as in this case by a command written by the Australian Dealer they control the creation of the surface and the settings / parameters that are being assigned - it looks like they are doing it right, however there is something different about this surface to a TBC surface that is created by TBC natively - and that is what is tripping up our ability to extract the drape lines that are evidently in the surface that has been created. I did see that on Import of the file, the surface was not visible on Zoom Extents and that it did not show up until I changed one of its plan view properties - Then it shows up, so the importer is not doing something it should be doing and that may be what is tripping us up - will get to the bottom of it.


Thanks Alan great help

The issue is fixed now and and update has just been posted (Friday pm at 5:22 and still working …)