Working with Infraworks360 and Coordinate Systems

[Anonymous]

Hello, 

I have recently been working with Infraworks 360 and Civil 3D for a studio project. However, whenever I import an infraworks model created by Model Builder into civil 3D, the surface would be tilted. I had posted inquiring about this issue here, where I learned that the rotation of the surface is expected due to the conversion of LL84 to a UTM coordinate system. 

Now, I understand that the rotation is expected, however, the import in Civil 3D is nonetheless not oriented to True North. this was evident when I overlayed the cadastral dwg from the land registry on top of the imported features. Ive been going over the documentation for both map3d and civil3d and still have trouble understanding Coordinate Systems. 

What do I need to do in order for the Infraworks import to be oriented just like the cadastral drawings? The Infraworks Model location is in South Korea, so when importing do I need to use a Korean Coordinate system?

[Pointdump]

Tkahng,

"...the conversion of LL84 to a UTM coordinate system."
"...oriented just like the cadastral drawings..."

I don't understand. Can you elaborate a little, maybe with a Screen Shot or two?

As for "True North", do you mean AutoCAD Top-of-Page or Geodetic North? AutoCAD is flat and the world is round. When you convert one to the other, something has to give.

 

Dave

[Anonymous]

Dave, 

thanks for that diagram, it gives me a lot more understanding about coordinates. What I mean is that I wish to have the Infraworks exported to C3D to be True north as in autocad top page. I do understand that something has to give, but if I acquire any features or data through infraworks, when relaying to other groups who need their data to be similar to other drawings they receive(usually drawings of that area from other surveyors), so I will have to manually rotate it. however, if I reimport certain features from the exported file that was rotated, the features would be slightly of axis. 

so something has to give, but what can I give instead of the top-page True North? Or if I do rotate the exported infraworks so that the orientation is in traditional top page true north, what steps do I have to take to reimport new features without them being dislocated?

[ITandCADguy · Accepted solution]

Maybe I'm not quite understanding the problem yet, but...

Assuming that you have set the coordinate system in C3D and imported the Infraworks model, how about creating a new UCS?

In your new UCS, simply select the orientation you wish to use as plan north.  Then you can set PLAN CURRENT in the drawing.  This will re-orient the drawing so that plan north is up on the page.

If/when you need to import more data, or export back to Infraworks, the correct coordinate system is still in your drawing, as nothing has been moved or rotated.

[Anonymous]

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@Anonymous wrote:

Maybe I'm not quite understanding the problem yet, but...

Assuming that you have set the coordinate system in C3D and imported the Infraworks model, how about creating a new UCS?

In your new UCS, simply select the orientation you wish to use as plan north.  Then you can set PLAN CURRENT in the drawing.  This will re-orient the drawing so that plan north is up on the page.

If/when you need to import more data, or export back to Infraworks, the correct coordinate system is still in your drawing, as nothing has been moved or rotated.

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Im pretty sure you got what im trying to say. Im more familiar with Revit than Autocad, so I thought that given the geolocation data, there would somehow be a fixed "True North/Project North". Ive done what you recommended an its all good, even when Ive rotated the UCS in ridiculous angles the exports fell in where they all should be! This cleared up alot of uncertainties ive had, thanks for the info.