AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

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Random shift in northing and easting

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01-21-2013 01:43 PM

Civil 3D 2013, SP1, Windows 7, 64-bit - I've got a user who imports points into the survey database and RANDOMLY the points will be shifted on average 27 feet in the northing and 4 feet in the easting.  She notices this becuase she'll check a point and see tht the northing and easting varies from the grid northing and easting (I've attached an image to view)  She will then discard the drawing and begin a new one only to import the data and now it imports correctly.  The behavior is completely random and it's happening on multiple projects.  All the projects begin with the same template.  All the settings (drawing settings and survey settings) have been set to US Survey Foot.  It's weird because once the issue is noticed it can be fixed by simply beginning another drawing and re-importing the data, but it has happened on projects where she's already got pre-existing data.  Any ideas on what may be causing this?

 

Thanks in advance,


Jason

Jason Porter
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Post 2 of 12

Re: Random shift in northing and easting

01-21-2013 03:01 PM in reply to: PorterCAD

Sounds like you are importing them with International Feet when it should be US Survey Feet.  Right-click on your survey database and select Edit Survey Database Settings.  Change the International Feet to US Survey Feet.  You will have to re-import the points after you fix this.

If the issue was resolved by this method, please click on "Accept As Solution"
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Post 3 of 12

Re: Random shift in northing and easting

01-21-2013 04:31 PM in reply to: PorterCAD

Check to be sure you have the same coordinate system selected, not just units.

 

Surveyor Lee

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Re: Random shift in northing and easting

01-22-2013 12:06 AM in reply to: PorterCAD

Yes, I would check the coordinate system. Here in Australia, we used to use AGD66, but now using MGA94. Coordinates in the old system are offset by approximately 150m, east and north. This used to cause all manner of confusion until people got used to it. I'm sure the same has happened just about everywhere over the world at one time or another.

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Post 5 of 12

Re: Random shift in northing and easting

01-28-2013 07:05 PM in reply to: autoMick

I've verified all your suggestions in some of the past projects and current ones.  All the settings are correct and in line with your suggestions. The weird thing. . .remember, this happens randomly.  All the settings are the same throughout each project.  So why does it randomly shift the coordinates?  And why is it always the same (or similar) distances?  Maybe it's something on our systems. 

 

Thank you all for all your input.

 

Jason

Jason Porter
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Post 6 of 12

Re: Random shift in northing and easting

01-29-2013 02:29 AM in reply to: PorterCAD

I guess I'd start basic troubleshooting - is it only one file (or group of files?), is it only affecting one template? is it only one computer or all of them? etc. Is it only after a certain command (is it truely random)? Is the offset amount the same? what amount is it offset by (anything familiar?)? etc. etc. Is the offset permanent or does it fix itself later?

 

Are you able to post the file?

 

Interestingly, I had a similar issue occur on one drawing just today - I haven't had time to investigate yet, but I noticed that some drawn objects were offset in relation to the underlying Bing imagery. It might be the imagery georeferencing has been altered, or I accidently moved stuff, or maybe something more sinister like you're experiencing :smileysad:

 

I'll have to do some checking on my file.

 

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Post 7 of 12

Re: Random shift in northing and easting

01-29-2013 05:17 AM in reply to: PorterCAD

If you insert a drawing with the shifted points in to a new one created from your template and reimport the points, overwriting the old ones. Does that bring the points in properly?

 

What is the original source of the points? Were they ever converted from LDT points?

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Re: Random shift in northing and easting

01-29-2013 07:33 AM in reply to: AllenJessup

Yes, I've started basic trouble shooting.  Here are the answers to your questions. . .

  • We notice the issue when we begin a drawing and then dump the survey (ASCII) points into the drawing.  We check a few points and notice the points have shifted.  We can kill that drawing and begin a new drawing (with the exact same template) and then the issue is gone. 
  • We've begun a new drawing with the Imperial NCS template (out of the box) and with a couple of others.  Again it's random, so sometimes it works and sometimes it doesn't, and it doesn't matter which template we use. 
  • The offset amount is averaging 27 feet in the northing and 4 feet in the easting.  Both are always in the positive shift direction. 
  • The offset is permanant and doesn't ever resolve itself.
  • It's so random that we can be working in a drawing where we've inserted points in the past and have been working on it for some time.  Then we get new points and import them only to see them shift. 
  • The points were not originally LDT points.  These are newly gathered points from our surveyors.  They are your typical PNEZD comma dilimitted ASCII point files.

I will try the suggestion of taking the shifted points and inserting them into a new one to see if that works.  Now I just have to wait until the issue happens again. We're now logging events:

  • When it happens
  • Time of day it happens
  • Whose system it happens on
  • If we disconnect from the network will it happen 

 

Thanks for all the input.  If I find anything that resolves this I'll repost. 

 

Good day to all,

 

Jason

Jason Porter
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Post 9 of 12

Re: Random shift in northing and easting

01-29-2013 02:09 PM in reply to: PorterCAD

Run the Base command.  Make sure it is 0,0,0.

 

Bill

 

 

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Post 10 of 12

Re: Random shift in northing and easting

01-29-2013 03:59 PM in reply to: PorterCAD

Have you verified that he surveyors gathered the point coordinates on the same coordinate system?  If they gathered them in one system and converted them to another, you could be getting some that are not on the same system.

 

 

Surveyor Lee

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