Grading Error! What Caused it?


Grading is an area in Civil 3D that people have a love-hate relationship with; they love it when it does what they want it to and doesn’t crash, and they absolutely hate it when it errors out, crashes, corrupts drawings, or anything similar. Recently, I ran across someone whose drawing was producing the following error;  “Error – Attempt to evaluate a plane with zero normal”. They informed me that they had several feature lines in their drawing. They had done some grading and made a surface. They had other feature lines in the drawing and they wanted to create another site and move the breaklines to the new site. They decided to create an infill in the middle of some of the feature lines. After doing so, they would save the drawing and close out. Upon reopening the drawing, they would receive the before-mentioned error and would not be able to reopen the drawing. In looking a their drawing that was still good, I suggested the following work flow:

1. If you want to move feature lines to a different site, create that new site first.

2. Select the feature lines, right click and select move to site.

3. Select the newly created site to move the feature lines to.

The next thing to do is instead of creating an infill, create a surface from the feature lines which will “fill in” the middle anyways. Follow these steps to do so:

1.Create a surface definition in prospector.

2. Select the feature lines, right click and choose “add to surface as breakline”.

3. Choose the newly defined surface and there you go!

After trying this work flow, the drawing had no issues and I was able to utilize the feature lines without using grading commands.

Civil Infrastructure software is my main professional interest. Civil 3D, Infraworks, and Recap are what I work with mostly. I have been with CADsoft Consulting for over 10 years now. I got my start using Softdesk and AutoCAD R12 in DOS. My wife and I have four children and I am a die hard Red Sox fan.