Splines and DGNs

[Anonymous]

Right, Hi folks.

I've been getting MicroStation files for looking at surfaces from a specific client, and they refuse to send me anything else. My biggest issue with this is that they supply their surfaces themselves as DTM files, which I cannot import (unless there is a way, please tell me there is a way!). So, since I can't import these files I need to import their 3D linework files they supply.

These DGN files come through as Splines. And I am finding Spline really really hard to work with, especially when it comes to creating surfaces. So I have a few questions in regards to this.

1. Can I import the DGN lines as 3D poly's instead of Splines? I assume it does this due to 3d arcs.

2. How can I make a surface attach to more places along the Spline

3. I've tried converting the Splines to Polys, but I don't understand the "Precision" - can someone please explain how it works because either my line doesn't have the curve I can see in the Spline, I end up with waaay too many vertices for the surface construction, or it crashes because it wants to do way too much. Thoughts?

[Neilw_05]

If your goal is to have a functional surface model, I suggest you use the Civil Engineering Data Translator vs. trying to recreate the surface from CAD objects. The data translator converts surfaces in DTM format to C3D. You can find more info about it in the help system.

[doni49]

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@Anonymous wrote:

Right, Hi folks.

I've been getting MicroStation files for looking at surfaces from a specific client, and they refuse to send me anything else. My biggest issue with this is that they supply their surfaces themselves as DTM files, which I cannot import (unless there is a way, please tell me there is a way!). So, since I can't import these files I need to import their 3D linework files they supply.

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I've never used this so I can't say how well it works but......

http://help.autodesk.com/view/CIV3D/2017/ENU/?guid=GUID-DD97306F-8584-4A84-A598-DEE85FEC817F

[Neilw_05]

Hi Doni,

I believe you are referring to the "Import from Inroads" command in the list you provided. Per the help file, that command initiates the Civil Data translator. It's just another path to the same tool. 

[doni49]

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@Anonymous wrote:

Hi Doni,

I believe you are referring to the "Import from Inroads" command in the list you provided. Per the help file, that command initiates the Civil Data translator. It's just another path to the same tool. 

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That's a little disappointing.  When I was looking for a solution, I came across an old thread that asked the same thing.  The last post in that thread (link below) said:

Now you can transfer the .DTM file to the Cloud and get the xml file after that!

https://forums.autodesk.com/t5/autocad-civil-3d-forum/import-dtm-into-civil-3d/m-p/6572888#M312550

[doni49]

Further research (via the link for that ImportFromInRoads command) shows this:

Import Bentley InRoads Project Data: Use this command to translate DTM and ALG files to files that can be used in AutoCAD Civil 3D.

[Neilw_05]

The way the translator works is you upload your files (.DTM files in this case) to a cloud server for processing. When it is done you retrieve the resulting files, typically a C3D drawing for each surface or alignment. Surfaces can also be retrieved in XML format.

I've only used the translator a couple of times. The process took a long time and sometimes it failed. I only ran it as a test since I have Power Civil which converts any Geopak data we have to work with.

[Anonymous]

I'll have a look into those suggestions today, but I do still need info on the Splines, since I do still need to use them a bit, but hopefully not for recreating the surface anymore.

[autoMick]

Regarding the DTMs - the data translator on-line service already described above is the only way I know of unless you happen to have microstation.

I use it regularly now and have found it reliable. You need to be signed into your autodesk account, then the tool allows you to upload your DTM file. It gives options as to what you get back (I just select triangles) and off it goes. You then open the "job monitor" which will allow you to download the converted files - you get a DWG with a surface as well as an XML which the surface references. I've looked for a desktop based converter in order to avoid the upload, etc. but haven't located anything. There is a Bentley viewer app which at least allows you to see the microstation file (check extents etc.)

As for the splines - I find even the lowest precision gives a ridiculous amount of vertices. One neat thing I stumbled upon is that you can MAPEXPORT splines as shapefiles, and then MAPIMPORT those same shapefiles, which effectively converts the splines to polylines and culls out all the redundant vertices at the same time. Maybe this will help?

Cheers

- Mick