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Account for coordinate system differences when data referencing

Account for coordinate system differences when data referencing

If a surface (or any other feature I'm guessing) from a drawing with one map coordinate system  is shared as a data reference and then linked from a drawing in another coordinate system, there is no coordinate system conversion and the shared feature will not be in the correct location.

Please provide the ability for shared drawing objects to carry their coordinate system information and allow for the appropriate conversion when creating a data referencein a different drawing.

Thanks

- Mick

8 Comments
rl_jackson
Mentor

I would have to agree, this is something that you can do in a convoluted way in MAP but still C3D does not respects systems even though the list exist. This should work for all objects. If I'm in NAD27 I should be able to got to NAD83 without issue and my data respect that.

K-Mart61
Advocate

I too would have to agree!  Civil 3D is severely lacking in this functionality.  Thanks to @autoMick for bringing this to the fore front. 

autoMick
Advisor

Thanks guys, to add to this, it would also be good if "Paste to original coordinates" brought up the option to do the coordinate transformation where applicable. There are many times where I will copy some line work from another drawing and paste into another. Obviously if the coordinate systems are different I'd have the same issue as described above.

Cheers

- Mick

autoMick
Advisor

I've got the unfortunate distinction of continuing to be involved in a project that utilises two coordinate systems and has a long history of survey data (and future data) which will continue to mix these (don't ask!). I've found that the ADEQUERY function (which I think is probably what @rl_jackson is referring to above does work for simple linework, but when dealing with large surfaces, etc. there just doesn't seem to any practical option but to got back and regenerate the data from transformed points. 

I've never realised what an issue the coordinate transformation thing was until this project and I'm really hoping we don't have to move to another CAD platform to accommodate it.

I would love to see an "Accepted" on this idea!

Thanks

- Mick

BrianHailey
Mentor

I'm by no means a coordinate system conversion expert but, I have a question on this topic. What happens when curves are converted from one coordinate system to another? If the shape of the data changes (not just a move/scale/rotate), doesn't that mean that the curve in one coordinate system isn't a curve in the other coordinate system? Or are the differences so minor that it just doesn't matter?

rsauerYSAX6
Explorer

@BrianHailey I'm not a grand coordinate transform expert myself, but my understanding is that it depends entirely on the scale of your curve. Small curves (hundreds of feet in radius) shouldn't see any appreciable difference. If you draw a linear path on Google Earth, for example, small paths display as effectively linear but the larger you go, the more the "straight" line curves. However, arcs can be defined as segment endpoint coordinates and a center coordinate. For something like an alignment, you'd want a circular arc to remain as a circular arc, so transforming the three data points should retain the arc's geometry. Also, if you're staying within the same projection (mercator to mercator, for example) I'd be surprised if this was an issue. moving between a state plane in Lambert Conformal Conic to UTM may be more difficult because you're changing the projection, not just the datum. 

 

 

anw52
Explorer

I would also like to see xref's transform coordinates.  My boundary retracement survey drawings must be on the record bearing system that the original surveyor chose.  Sometime our topo survey and/or design drawings are on a different system.  Our designers will xref my boundary drawing into the topo or design drawing, and then panic when the boundary lines aren't in the correct location.  Civil 3D can correctly place an aerial image that is in a different coordinate system.  I don't see why xref's or data references that come from drawings with an assigned coordinate system can't do the same.

declan_g
Enthusiast

This would be a massive time saving feature for Civil 3D users in Ireland we have two main coordinate systems ITM and ING. ING is redundant as it is not compatible with GPS but still used by our water utility body who insist on coordinates in this format. It creates unnecessary work transforming all our models at the handover. 

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