Units of DWG exported from Microstation

[janis.prodnieks]

Got a DWG that is exported from Microstation. Units of that DWG are meters if opening with AutoCAD LT (2020). If opened with Civil 3D (2020) units are Feet. Any idea how to make my C3D open such DWG with meters as units?

[AllenJessup]

Are you saying that the drawing is being scaled of that the units are reporting as feet? IOW. Is a 20 meter line now measuring as a 20 foot line?

This could involve;

INSUNITS

INSUNTISDEFSOURDE

INSUNITSDEFTARGET

or Coordinate System settings.

The units setting only affect how the distances are reported or how they are scaled when inserted.

[janis.prodnieks]

Nothing is scaled. INSUNITS are different, depending whether the file is opened with AutoCAD LT or Civil 3D. Here's the screenshot of what's visible in UNITS window in both. I want to understand how to make Civil 3D to read that units for this DWG are meters.

[AllenJessup]

Civil 3D doesn't work well with the Units command. I'd suggest either setting a known coordinate system from the settings tab

or using AECDWGUNITSSETUP to set the units to meters.

[ChicagoLooper]

Just because 2020 LT is displaying meters doesn't necessarily mean it's in meters. You are holding back on info, need full disclosure to troubleshoot. Who created the dgn? Someone in USA or another country? Is site in US or outside in foreign country? What is nearest major city and state?

I'd be more interested if units are ground units or grid units, not whether meters or feet.

[janis.prodnieks]

Of course, it's possible to set units right using Civil 3D Settings.

But it doesn't answer the question why same DWG gets read with different units in different kinds/flavours of AutoCAD. Why there's inconsistency with units between ACAD LT and C3D?

[janis.prodnieks]

I'm not sure what do you mean with ground units and grid units. The units used for drawing are meters. If I measure a line and it's length is 30 in AutoCAD it means it's 30m long. I'll ask the guy with Microstation to provide me simple DWG with one 30m long line and I will post that DWG here once I get it.

The country is Latvia but I don't see why it would have any relevance to the matter.

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@ChicagoLooper wrote:

Just because 2020 LT is displaying meters doesn't necessarily mean it's in meters. You are holding back on info, need full disclosure to troubleshoot. Who created the dgn? Someone in USA or another country? Is site in US or outside in foreign country? What is nearest major city and state?

I'd be more interested if units are ground units or grid units, not whether meters or feet.

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[ChicagoLooper]

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@janis.prodnieks wrote:

I'm not sure what do you mean with ground units and grid unit

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And that's your problem, you need to understand, ground and grid U-N-I-T-S are different. And top of that, you need to make the units geospatially accurate (whatever the units are determined to be) against a 'known' reference system. 

BTW, if you're gonna ask the microstation guy for a new file, then ask to have it exported to kml, not dwg. Then import the kml to C3D. (Don't forget, before it's exported to kml, you must give the dgn a coordinate system beforehand.)

Microstation: To assign coordinate system go to Tools=>Geographic=>Open as Toolbox

Microstation: Export to kml.

The reason the country makes a difference is when you bring in the dgn linework into your AutoCAD drawing, the AuoCAD drawing needs to referenced against a known coordinate system. this means your drawing must be assigned a CS that's relevant to Latvia and not someplace else such as Nova Scotia or New Zealand.  

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[jae.kwon]

With AutoCAD and Civil3D you are 100% responsible for setting the correct units for the drawing.

For AutoCAD, just set the units to what it's supposed to be. For Civil3D, correctly set units and also use the correct template (imperial or metric).

[rl_jackson]

If your not using the Metric shortcut for C3D then your probably fighting an uphill battle. All units need to match in C3D. No way around that. 

[janis.prodnieks]

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@ChicagoLooper wrote:

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@janis.prodnieks wrote:

I'm not sure what do you mean with ground units and grid unit

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And that's your problem, you need to understand, ground and grid U-N-I-T-S are different. And top of that, you need to make the units geospatially accurate (whatever the units are determined to be) against a 'known' reference system. 

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Well, I made a little search on what are ground and grid units. If I got it right (100 grid units might end up like 100.1 ground units on actual ground) this is completely irrelevenat to the issue (we get the geometry in grid units).

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@ChicagoLooper wrote:

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BTW, if you're gonna ask the microstation guy for a new file, then ask to have it exported to kml, not dwg. Then import the kml to C3D. (Don't forget, before it's exported to kml, you must give the dgn a coordinate system beforehand.)

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The formal deliverable we get is either DGN or DWG. And the idea is to figure smoothest way to get a good DWG. Thanks for the idea and Miscrostation screenshots but I don't see using KML as a reasonable option if adjusting DWG settings in C3D might be easier.

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@ChicagoLooper wrote:The reason the country makes a difference is when you bring in the dgn linework into your AutoCAD drawing, the AuoCAD drawing needs to referenced against a known coordinate system. this means your drawing must be assigned a CS that's relevant to Latvia and not someplace else such as Nova Scotia or New Zealand.  

In the simplistic way we do things (like with AutoCAD LT), there's one and only coordinate system in Latvia. When inserting/XREFing something with the insertion point 0,0,0 and scale 1 it all works. That's it and every engineer/stakeholder lives with that without assigning any particular CS somewhere in the file settings. Everyone just know this linework is in the only existing CS we use. For XREFing nicely it's important the INSUNITS are correct, hence my question. XREFing goes wrong because of automatic scale factors if a file containing linework in meters (grid units) has Feet as INSUNITS. And of course in C3D where design is carried out we assign the CS correctly.

[janis.prodnieks]

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@rl_jackson wrote:

If your not using the Metric shortcut for C3D then your probably fighting an uphill battle. All units need to match in C3D. No way around that. 

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I tried running Civil 3D 2020 Metric shortcut with same results - units are Feet if opened with C3D, Meters if opened with AutoAD LT. Got the file, attaching to this post (zoom extents to see the lines).

Variable MEASUREMENT in this DWG is 0, indicating it most likely comes from Imperial setup.

[janis.prodnieks · Accepted solution]

The issue appeared to be with a "seed" file used by Microstation user to create his exports to DWG. I provided blank DWG, saved with AutoCAD LT and correct UNITS and gave it to him to use as "seed". Test DWG I received has meters as units in both - AutoCAD LT and Civil 3D.

Though thanks for your input!