I created the surface below from my corridor by selecting the 3D elements, but when I attempt to export the surface to a TIN, XML, DTM. I get the error mentioned in the title. How do I go about making this terrain valid? I have already removed rules from…

I am trying to append a .dat file to include breaks. I start in DTM>Extract>Graphics, and in the "Extract Graphics" window I use the following settings: File Type : Ascii, File Open : Append, Feature : Breaks, Mode : Extraction, No stroking, Decimal …