I was teaching a Civil 3D class a few weeks ago, and we were discussing surfaces and how to edit them.  One of the students had a point file which was a survey, which contained a creek that ran through the center of it.  He imported the point file into the drawing using the survey database.  After the file was imported, a surface was created. All went well creating the surface, except the creek area, which did not have any TIN lines.

The surface was created using the point group from the import, along with the survey figure lines.  All of the points in the creek area were included within the point group, but for some reason Civil 3D would not draw the TIN lines in that area.  The student tried adding TIN lines into the surface, with no avail.

Since he needed the surface for the entire site, he had not added a boundary.  As we discussed what to try next in the class, another student mentioned that he had previously ran into the same issues with another drawing, and called Autodesk to see if they had any ideas what to do.  Autodesk recommended adding a outer boundary to the surface, drawn outside the entire site.  As soon as the surface was rebuilt, the creek area filled in nicely, and the surface was complete.

Luckily, I always learn something new at every class I teach, and this was one of the more memorable instances that I have come across.   It always helps to think outside the box, or inside the boundary, whichever the case may be!

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