Projection issues with DGN file in ArcMap 10.2

[StephanieSorensen]

I am currently having this problem with two different projects - the designers send me Microstation (DGN) files, and a lot of the time I have problems with them because they either didn't assign a horizontal datum to their files, so they are MIA, or it has a datum that is used less frequently, which isn't a problem once you know what that projection is.

However, with these two projects, the files show up approximately 50 miles southwest of where they are supposed to be. I have the following information about the Microstation files:

Horizontal Datum: NAD83(94)
Vertical Datum: NAVD88
Zone: SPC Georgia East

They also sent me the reference point coordinates from their "control package."

#903 �?? 993374.916N 546984.982E
#904 �?? 993853.380N 547704.008E


If anyone knows what I can do on my end to fix this, please let me know!

[MelitaKennedy]

So Johnson County? The control points are in US survey feet then. 50 miles southwest makes me think the rest of the data is in meters instead. Anyway, that there's some feet/meters issue occurring.

Melita

[StephanieSorensen]

Thanks for your response, Melita, and that is a logical guess - it is what I had guessed too. But I have tried setting my map to the meters projections of NAD83, and that puts the file even farther away and to the northeast.

[MelitaKennedy]

Does the CAD data show up with a defined coordinate system? Or is it listed as unknown? If it's known, try redefining it to the other unit.

Melita

[StephanieSorensen]

No, the coordinate system is listed as unknown. If it is something on their end, what is it that they need to do? I don't believe they know, or they would have fixed the problem already.

[MelitaKennedy]

I should have asked this already--can you post the extents of one of these CAD files? I have heard about DGN files having a scaling factor. I don't remember off-hand what it's called. But maybe I can at least identify what's happening when I see the extent values.

Thanks,
Melita

[StephanieSorensen]

CAD Dataset Extents

Min X: 367363.176656486                   Max X: 370427.436662666
Min Y: 812100.373416666                   Max Y: 817584.06320998
Min Z: -1.03920077284177e-1             Max Z: 320.488

[MelitaKennedy]

CAD Dataset Extents

Min X: 367363.176656486                   Max X: 370427.436662666
Min Y: 812100.373416666                   Max Y: 817584.06320998
Min Z: -1.03920077284177e-1             Max Z: 320.488

Hi Stephanie,

Okay, they do look like NAD83 GA East (feet) coords, in Dodge county. Is that correct?

As a long shot, if that's not the correct location, is it in Montgomery county? If so, maybe it's NAD27 (feet) GA East.

[StephanieSorensen]

No, it is in Johnson County, which is my problem. It shows up in Dodge for me too. I have tried assigning a NAD 27 projection to my map, and that didn't help. So you agree that it is on their end? They keep telling me that it all lines up in Google Earth.

[MelitaKennedy]

No, it is in Johnson County, which is my problem. It shows up in Dodge for me too. I have tried assigning a NAD 27 projection to my map, and that didn't help. So you agree that it is on their end? They keep telling me that it all lines up in Google Earth.

Bleargh. I think so, that it's on their end. Feel free to tell them Esri's projection expert can't figure it out either!

Another thing to check is whether the CAD data looks like it's the correct size when the data frame is using a feet-based or meter-based coordinate system.

The offset is much too large for a standard grid-to-ground correction or even int'l vs US survey feet.

Melita


(I finally found a reference to the Microstation settings I mentioned earlier. It's the global origin and units values)