Some imported LandXML or other files contain corrupted TIN structures with unreported holes.

This can cause issues when calculating f.ex. a road model or similar. Sometimes it is possible to visually confirm these issues by viewing the surface in a Plan View, and then to choose the Draw All presentation setup. You may see some dots and shapes on the surface that you didn't expect.

To improve this:

• Make a Ground Surface task or Sub Surface task.
• Select the LandXML terrain surface as input.
• Go to task Settings > TIN priority. CHECK OFF “Keep TIN structure”.
• Go to task Settings > TIN breaklines. CHECK ON “Use TIN edges from surface geometry as breakline. (Will increase calculation time)”.
• Save the setting changes.
• Finish the task.

With these settings the retriangulation will break up the TIN to only points and retriangulate the points. This could cause the triangulation to look different than the LandXML input file. Because of this we have also set the task to use the TIN edges found in the input as breaklines. As an effect, the Ground Surface task should produce identical TIN structure to the input, as long as none of the data from the input are overlapping.

Long triangles outside of the original surface:

The output from this process may cause triangles to go outside of the original data. This is because the triangulation only considers the points and the original surface triangle edges.

To improve the results you could either:

• Go to the tasks Settings > TIN > Remove long-edge triangles at edge of model, and set an appropriate length.
• Set the original surface as the 'Outer Boundaries' in the task. Note that the output may vary depending on the quality of the original surface. An alternative is to draw a polygon with the Features tool.