Datum transformation

[Allan siriba]

I have just finished designing a 56km road. On completion we have been asked to tie the road to the national grid used by our local authorities. My coordinate system is WGS84 and the national grid is ARC 1960. The xyz shifts, given by the surveyor, between the two coordinate systems in WGS84 are δy=-63.447 δx=-13.931 δz=-0.232. I have tried having a geocentric translation on civil 3d 2012 but to no avail. What would be the simplest approach to applying this shift without having to start from scratch?

[Emigrato]

Well, did you just try simply:

1] _MOVE
2] select all
3] as source point, type in 0,0,0
4] as destination point, paste -13.931,-63.447,-0.232

?

[Allan siriba]

I did try move but my existing ground levels on my profile views were all messed up and the corridor wouldn't budge. Having said that move still feels like the most viable option.

[CyberAngel]

Have you tried redefining the coordinate system for the drawing itself?

[Emigrato]

If you don't wanna physically move your objects, what about shifting your UCS origin..?

1] command _UCS
2] type in _OR
3] paste -13.931,-63.447,-0.232 as new origin.

I know that's a dirty trick, but...

[Allan siriba]

How do i redefine the coordinate system? or does redefining the coordinate system involve editing the drawing settings and transforming a reference point? I have tried that but it does not reflect.

[Allan siriba]

Shifting my UCS origin seems to work for my grids but it does not reflect on the profile views and the alignment details. For example the coordinates for the start and end of my curves do not change and are still WCS coordinates. My profile views also do not reflect the delta z change.

[CyberAngel]

How do i redefine the coordinate system? or does redefining the coordinate system involve editing the drawing settings and transforming a reference point? I have tried that but it does not reflect.

Open the Settings tab of Toolspace. Right-click on the drawing name (first line). Select "Edit Drawing Settings." On the "Units and Zone" tab, you can define the zone category and the coordinate system for your area.

If that doesn't work (and I suspect it won't), you'll have to physically move your objects. The surface(s) may take a little extra work, but there's a utility for that. The profiles and corridor should move dynamically with the objects you used to define them, or you'll have to recalculate/rebuild them (not re-create them).

Profiles work off the World UCS. At least, I don't know of any way to change that.

[Bill_Myron]

I would do the move in the X and Y coordinates only.

Then I would use the Civil 3D tools to move the surface and any profiles by -0.232

I would not recomend changing the UCS origin. Civil 3D starts acting very strange if you are not in UCS WORLD.

You have a rather easy move to do, as you have a defined movement, and do not ahve to SCALE anything.


We are always having troubles between Ground and Grid Co-ordinates.