topic Re: Rotating entire project changes Surface and Point elevations in Civil 3D Forum

Rotating entire project changes Surface and Point elevations

Anonymous — Fri, 16 Feb 2018 22:51:51 GMT

Here my situation.

I have a project that was originally surveyed using the north zone. The client wants the coordinates system for the south zone. (North south line splits the town).

When I try to rotated the entire project based on angle the Surveyor provided it changes the survey point elev's and the surface elevation.

The coordinates for the points change to the correct zone as needed.

I have made sure the "Allow checked in points to be modified" is set to true. I am using the standard autocad rotate command from tool bars. Is there a different way to rotate that doesn't change the elevations?

What am I missing?

2015 in use

Dave Z.

Re: Rotating entire project changes Surface and Point elevations

Pointdump — Sat, 17 Feb 2018 00:35:49 GMT

Dave Z,

"When I try to rotate the entire project based on angle the Surveyor provided it changes the survey point elev's and the surface elevation."

I don't understand. Why are you rotating the drawing?

"The client wants the coordinates system for the south zone. (North south line splits the town)."

So the town is on a County Line in the middle of Kansas?

If this is the case, then you could <<<extend the range>>> of either the North or South Zone.

Dave S

Re: Rotating entire project changes Surface and Point elevations

Anonymous — Sat, 17 Feb 2018 01:31:25 GMT

Yes the town is on the north south line in middle of kansas.

I am not useing bing maps at all. I am trying to rotate the drawing and survey info including the surface and all design info to match the south zone. When i do rotate the coords are correct but the surface and survey pnts change elevations, which i dont want.

Re: Rotating entire project changes Surface and Point elevations

Pointdump — Sat, 17 Feb 2018 02:02:31 GMT

Dave Z,

OK, so you're transforming a North Zone drawing to a South Zone drawing, right? I just don't understand the "rotate the drawing" part. More details on that please.

Transforming COGO Points and AutoCAD Linework, like Contours, is fairly straightforward. Transforming a Surface, Alignment, Profile, Parcels, etc., is a bit tougher.

Dave S

Re: Rotating entire project changes Surface and Point elevations

Anonymous — Sat, 17 Feb 2018 02:51:17 GMT

Need to do the corridors, surfaces, profiles....ect. the whole kit n cabootle.

Re: Rotating entire project changes Surface and Point elevations

Pointdump — Sat, 17 Feb 2018 11:51:30 GMT

Dave Z,

With the exception of COGO Points, Civil 3D won't directly Transform C3D Objects, like Surfaces and Parcels, from one Coordinate System to another. You'll have to Explode any C3D Objects into Dumb AutoCAD Objects and then use Map 3D Attach-and-Query to Transform. I would extract the Triangles and Breaklines to re-create the Surface in the South Zone.

Beware the pitfalls of this Transformation. If liability is an issue, you might recommend having a Re-Survey.

There's some good reading from the Best and Brightest <<<Here>>> and <<<Here>>>.

Dave S

Re: Rotating entire project changes Surface and Point elevations

Pointdump — Sat, 17 Feb 2018 13:04:45 GMT

Dave Z,

Oh, and as for the Translate-and-Rotate way to get to South Zone Coordinates (I see what you're doing now), there's a problem. The Grid Scale varies from the Northern Standard Parallel and the Southern Standard Parallel(The two places where the Map is Secant to the Ellipsoid). So unless your project is coincidentally exactly as far from the North Zone's Southern Parallel as the South Zone's Northern Parallel, you'll have a Grid Scale Issue. For a small project it might be of no consequence, but it's something to consider anyway.

Dave S

Re: Rotating entire project changes Surface and Point elevations

Anonymous — Sat, 17 Feb 2018 17:43:30 GMT

Thanks for all the input Dave.
I will get with the big boys on monday and show them your comments and see what they want to do.

Re: Rotating entire project changes Surface and Point elevations

rl_jackson — Sat, 17 Feb 2018 21:42:21 GMT

I find it quite odd that you would need to rotate the survey just because you changing it from North Zone to South Zone. This is just from my personal experiences, and I could be wrong, since I've not had to actual transfer a site out of one SP zone to another. But it does seem highly likely that there would be completely different coordinate systems.

Now that being said it might be easier to get the new coordinate using something like Corpscon as shown in the post that @Pointdump posted a link too, and set those points at the elevation of there corresponding point that why you doing a direct move and rotate without having the issue.

NOTE: when you do this move don't select the surface or surfaces it will update its position based on the data it was building from.

One other thing I realize that you points are on State Plane but I bet the surveyor had the GPS data calculate the ground position based in the field using a scale factor at the time of the survey.

Re: Rotating entire project changes Surface and Point elevations

Anonymous — Sat, 17 Feb 2018 22:16:36 GMT

How does corpscon deal with the alignments, profiles, corridors....ect. that are currently in the file. This project is about 80% complete

Re: Rotating entire project changes Surface and Point elevations

rl_jackson — Sat, 17 Feb 2018 22:39:59 GMT

It doesn't You would need to move each of you files in the same manner, assuming your DREFing/XREFing everything in your drawings. It's definitely wouldn't be a easy task.

I would ask this, if the property is clearly located in the NORTH Zone, and in that county, why is your client requesting you set into the SOUTH zone at this late stage in the game. Or is there an issue that the surveyor thought he was in NORTH when he was actually in the SOUTH Zone. For the later, I'm thinking a simple change of the system in the drawing may correct the problem, I've actually done that before and change my zone and got the correct LAT LONG values reported and moved along. (Disclaimer: I don't advocate or recommend that approach, but crap happens).

NOTE: If you drawing was set in the wrong zone, but the data was in the correct zone you would see the issue based on the LAT LONG of the point data not being correct.

Re: Rotating entire project changes Surface and Point elevations

Anonymous — Sun, 18 Feb 2018 14:56:52 GMT

Rl
There are no xref files attached. Its a small street replacement about 5 blocks. Its all in one file.

Re: Rotating entire project changes Surface and Point elevations

Pointdump — Sun, 18 Feb 2018 15:05:41 GMT

Dave Z,

Any chance you could post your drawing? An interesting problem, transforming Civil Objects.

Dave S

Re: Rotating entire project changes Surface and Point elevations

rl_jackson — Sun, 18 Feb 2018 17:24:34 GMT

It all being in one file then there is nothing to really transform, its just a matter of moving the stuff, and being on the correct state plane coordinate system. I'm not a big fan of grid, cuz most land surveyors still survey on ground but place stuff on grid coordinates with the scale factor already accounted for, therefore taking grid out of the equation. That's why I see this as just a move to the correct coordinates and nothing more.