Before the phones started ringing this morning, I was catching up on some early reading.and ran across this article by Donnie Gladfelter. Donnie is a great friend of mine, and I am one of the people that he worked with a few weeks ago on his perfect storm issue. I had to call him this morning to talk about this article, as one of his links was a tiny bit outdated and not very easily found during a normal search of our knowledgebase. We discussed it, and I told him that I would write this as a supplement to his already excellent article to explain a bit more in-depth what was happening.
What Donnie’s user had was your basic corrupt file. As he said, Audit was acting more like a random number generator (I did get a chuckle out of that) as it reported different numbers of errors each time. Recover wasn’t much better, and he had a mess on his hands. He was sweating, I was sweating, and to be honest, it really wasn’t all that hot outside. Numerous people became involved with this case, from the great technical minds over at Avatech to many different groups here within Autodesk. Working with QA, I learned much more than I thought I ever wanted to about overlapping feature lines.
See, everyone knows that feature lines on the same site interact with each other if they touch. But when that geometry overlaps, strange things can happen (note the italics – this is because strange things don’t always happen, but they certainly have the capability of happening. Oh yeah, and “strange things” in this context usually means that you end up submitting a CER.) With Update 2.1 for Civil 3D 2009, some undocumented commands were added that helps to detect those overlapping objects that can cause drawing instability. These commands have now been documented in (the updated) TS1101487. They include the AeccFindSiteOverlaps command, which is the first one that should be run. If overlaps are found on a site, then the command line will tell you which of the following commands should be run to get rid of the overlapping geometry: AeccRemoveDupFeatureLines, AeccRemoveAlignmentsFromSite, or AeccRemoveDupLotLines.
To see a bit more about how these overlapping objects can be removed, please take a look at this video that shows how to remove duplicate feature lines. To see it in a bigger format, click on over to our YouTube Channel.
I would like to point out something very important with this – this is not a magic cure-all tonic for any and all drawing corruption issues. This does not work all of the time, because you may not have overlapping feature lines. This command will move your feature lines to different sites, meaning that you might have to do some rebuilding of your surface or grading objects. As Donnie mentioned, think of these commands as an AUDIT for site geometry.