Implications of Rotating a Surface

There may be times where you need to rotate some Points you got form your survey crew.  However, these Points have already been used to create a Surface.  What is the best way to go about this?

Well, first thing to know is that you only want to rotate the Points, not the Surface.  If you grab both, it will end up doubling up the rotation of the Surface.  So make sure you are only rotating the definition of the Surface and then simply rebuild your Surface to see the corrected location.  But wait…there’s more!

Now here is where it gets a little tricky.  It is very important that you refrain from doing any editing of the Surface until you are sure that the Points are in the correct location.  This is because edits, such as deleting a TIN line, are based off of coordinate locations.  You are deleting a line from one coordinate location to another, not from Point to Point.  See the image below:

So while the edit is still present after you rotate the Points, it still references the original coordinate locations of that TIN line.  Which, after the rotation, will mean nothing to you or your Surface.

If you have already done your edits, the only way around this is to export the Surface out, via Land XML and then bring it back in, and rotate, as desired. 

So remember, get your Surface Definition all set before you start your edits!