Export AutoCAD Civil 3D Drawing to Microstation DGN

[klantz]

Hello,

I'm helping troubleshoot an error that is occurring during our export from Civil 3D to Microstation. We have a grading file that is georeferenced and has been set up in US survey feet. When we run through the export civil 3d drawing process we get a dgn that has a "foot" unit that is reading as International feet. When the Caltrans (CA DOT) person we're working with runs through the export of the same file on his machine using the Caltrans Civil 3D interface, the file exports correctly with US survey feet and the correct "foot" unit definition in Microstation. When looking at the two output dgn files independently, the x and y values of a similar line read the same, but when trying to reference one file into the other a storage unit error is generated. If we proceed to reference in the file, one is shifted a few feet. We're using all of the same export settings in Civil 3d: seed file, remapping file, color book, layer properties. I'm guessing there is a variable in our Civil 3D environment that is coding the foot unit differently than it does in the Caltrans environment. I've tried exporting with the coordinate system set and the "set autocad variables to match" selected and unselected, both generated the same incorrect file. Does anyone have a guess at what the unit variable is or have experience exporting a dgn using Caltrans remapping files? 

I did see this post https://forums.autodesk.com/t5/autocad-civil-3d-forum/conversion-to-dgn/m-p/6739241/highlight/true#M...

But these replies are all for post processing in Microstation and not really getting at the variable setting that would explain why it works correctly out of the Caltrans interface, but not out of ours even though our export settings are the same. My apologies if I should have posted a follow up on that post.

Thanks much!

Kristin Lantz

Civil 3D 2014/2016

Windows 8.1 Enterprise, 64-bit

[Jay_B]

This sounds like it might be a dgn seed file problem.

What dgn Seed file was used for Command:_Export > Export DGN Settings dialog > Specify seed file?

I'm going to guess that the Caltrans setup uses a custom seed file.

If possible, ask the dot user if they can check what seed file they're using to export.

[Anonymous]

I have to convert everything I do back & forth between dwg's and dgn's. I ran into issues with US Feet vs. Int'l. Feet. here is what I do.

First, do not use C3D to export to a dgn - mstn does a far better job converting a dwg to a dgn.

Set your UNITS in the dwg to whatever you want. Beginning in 2017 we can set the UNITS to US Survey Feet. This is what I do. Then export the dwg to AutoCAD.

Start a new dgn using whatever seed file is appropriate. Make sure your units are set to the same as the dwg - (in mstn) Settings>Design File, Working Units. make sure the master and sub units are set to the same as the dwg. Make sure that the STorage Resolution units (advanced button) uses the same base unit. if you are using a geographic coordinate system, all of the units should match this (in the exported dwg, too).

I also have to be concerned with layer--> level translation with all of the correct linetypes/styles, color & color table, lineweights, etc. to get this to come over right I have to use a seed file that everything is correct in - level parameters, linestyles and text styles loaded, etc. I make the dwg match all this as closely as I can, by name if nothing else, so that mstn knows what to do with it..

reference in the ACAD-<yourC3Dfile>.dwg created when you exported the C3D dwg. If the units are good it'll go ok. If not, you'll get a message saying there is a difference in units, are you sure you want to do this? Make sure that the scale of the reference is correct (multiply by 12 for Sheet models in mstn). Merge the reference into the dgn. everything should translate, although the C3D objects that were turned into blocks are turned into cells/shared cells and won't behave like you want them to always.

AutoCAD does a poor job of translating, I wouldn't go there. for some reason it usually adds an english to metric scale factor to my drawings when I open as a dgn, or reference them into a dgn.

good luck. you can go back and forth, but don't expect perfection.

[Anonymous]

Set your UNITS in the dwg to whatever you want. Beginning in 2017 we can set the UNITS to US Survey Feet. This is what I do. Then export the dwg to AutoCAD.

this may be your problem (if you have to export from C3D). use the UNITS command. it isn't good enough to just set the coordinate system in C3D - Mstn looks at the units as set by UNITS.

[Jay_B]

I'm still curious to hear if your dgn seed file used matched what the DOT was using?

[klantz]

Thanks for responding Jay_B.

Yes, I have all of the Caltrans seed files that they use. I used the same seed file (their State Plane, zone 5) that the Caltrans engineer used, but his was correct and mine has the incorrect unit definition. I also have the Caltrans units.def file loaded on my system as my go to units.def file to ensure I'm setup per Caltrans setup.

[klantz]

Thanks for the response, drenaud.

I have used a similar routine as you've described in the past (and its my work around now), but I'm hoping to get to the root of the "export from C3D" issue so I can use the Caltrans remapping files and avoid the extra formatting within Microstation. I always have some formatting work within MS, but it should be less if the remapping files do their job. Also, I'm exporting from C3D 2016, haven't installed 2017 yet, so I don't have the US survey feet option, but my drawing settings are set to US survey feet, Acad "units" is just decimal and feet.

As for the units definition within the Microstation environment, that's what is incorrect. I can see that the Caltrans' exported file reads correctly with the FT and TN units, whereas my exported file has different unit settings. When I update them within my dgn to match the correct Caltrans units, my file will overlay/reference to the Caltrans basemap in the correct location, but the physical x,y coordinates of a given line is not the same as what is in the Caltrans file.

I'm having our Ideate support look into this issue as well and he's asked me for a screencast, so I'll link that up once I've done it.

Thanks again!

Kristin

[klantz]

I've uploaded my screencast, but the status is pending so I've pasted in the URL.

I had played around with the working units within Microstation previously and was getting inconsistent results, but after exploring it more based on feedback provided, I think the file is now projected correctly. I'd still like to know if there is a setting with AutoCAD that can be changed to export correctly as it does when the Caltrans engineer does the export.

Thanks for all the helpful feedback!

Kristin

[klantz]

Here's my screencast.

[Jay_B]

Have you asked the Caltrans employee if they would watch your Screencast, to see if they notice any differences in the workflow?

[klantz]

Hi Jay_B,

Yes, I sent my screencast to their support person who was trying to help, but I haven't heard back yet. 

I also have our support contractor, Ideate, looking into it.

I'll update my post if Caltrans or Ideate figures out a fix.

Thanks for all of your suggestions!