Transforming .dgn files

jubxiejubxie Global Mapper UserPosts: 18
edited February 2014 in Vector Data
I'm trying to transform .dgn files and export them in their original condition (elevations/relative positions/rotations), with the new coordinates. I'm having trouble with the output from GM. The units and resolution come out very strange and metric. My input is NAD83/international feet - output NAD27/international feet and my output .dgn has metric resolution. I'm wondering if I am doing something wrong or ?? I cannot get the output to match an existing transformation, mostly I suspect, due to unit/resolution issues.

I've done a great deal of this type of coordinate system change in GM, but never had success with .dgn file outputs.

Thanks

Jimmy

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2014
    Jimmy,

    What version of Global Mapper are you using? Are you setting the projection on the Projection tab of the Configuration dialog to the output system and units that you want? That should determine what is written out to the DGN file. Does it look like the actual coordinates are converting units from feet to meters?

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • jubxiejubxie Global Mapper User Posts: 18
    edited February 2014
    Thanks Mike. I'm using GM 15.1.0 64bit. I'm bringing in the file in the correct State plane, NAD83, Ifoot. Changing the datem in the projection tab of the config dialog, and exporting. I'm doing some further testing. As it turns out, despite the .dgn files having International Feet for their units, if I import them as survey feet, they line up. Apparently, the original files were transformed in state plane, then converted to International feet. I was transforming in International feet. That is why I see a shift between the two, I think.

    This leaves me with the issue of the .dgn files having strange units coming out of global mapper and the text being rotated to 0 and moved to an elevation of 0. My experience has been that you don't want to have different linear units from resolution units. See screenshots of before GM, GM settings and after GM. This change in units also occured when I did not do a transformation, just a straight import and export.

    Thanks!!

    Jimmy
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2014
    Jimmy,

    I took a look at our DGN export and found that some of the units didn't appear to be set properly in the DGN file itself, so applications that use that information might scale the data wrong. Global Mapper would use the projection that you specify at load time so the unit information in the DGN header itself isn't really important.

    I have improved the units written out to DGN so that you should get 'ft' and 'in' for the units when export from a foot unit (there aren't separate US survery feet and international feet in DGN, at least that I could find. I have placed a new build at http://www.bluemarblegeo.com/downloads/global-mapper/global_mapper15.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v15.xx installation folder to give it a try. If you are using the 64-bit v15 version there is a new build at http://www.bluemarblegeo.com/downloads/global-mapper/global_mapper15_64bit.zip .

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • jubxiejubxie Global Mapper User Posts: 18
    edited February 2014
    Thanks. I will try it out in the morning.

    Microstation uses a file called units.def to define its handling of units. We use a slightly custom one, only to make the the difference between survey feet and international feet more human readable. I think survey foot is commented out of the units.def file by default.

    Any idea why the text is moving to an elevation of 0 and rotating to 0?

    Thanks again!

    Jimmy
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2014
    Jimmy,

    It looks like the elevation should be kept for text, but it would lose any rotation. Do you have a sample input file with the text where the elevation doesn't come through so I can try it? I might be able to do something about the rotation too.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • jubxiejubxie Global Mapper User Posts: 18
    edited February 2014
    Ok. Here's what I found in the GM version posted on 2-11;

    - The Linear units are reading correctly, but in the advanced settings, it is still changing the resolution units to meters from feet. I wonder if you could just read and write that information without changing it (assuming no change occurs in GM)? If a change from ifoot to Survey foot happens in GM, then it get sticky due to the way MS handles units in that units.def file. If I understand correctly, I could call survey feet, monkey feet if I wanted. I think it would write monkey feet into the header, and only MY units.def file, with monkey feet defined with the correct scaling for survey feet, would treat it correctly. Not sure what to do there. I've see Ifoot, foot, survey foot, svfoot, etc. I guess I could give you our overkill list of possible names for ifoot and survey foot.
    - The cells are being exploded, which is an issue for us. I've seen other programs ask for a cell library when writing out .dgn to keep this from happening.
    - The text seems to be changed to some kind of 2d feature. Fixing the rotation and elevations on the text would be deluxe.

    I've attached a before and after .dgn.

    Thanks as always!!

    Jimmy
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2014
    Jimmy,

    Can you provide the units.def file and do you know where that normally lives on a system? Perhaps we could try and find that file on the system or allow a user to specify where it lives. It is too bad MicroStation doesn't provide some standard names and abbreviations at least for commonly used units, like US Survey Feet and Internal Feet. If we can somehow decode the units at import we could maybe also make our own database for DGN export use as well, so if you imported a file with one abbreviation that abbreviation would be used on the next export. I'll look at the files and see if that is possible.

    There is an option for just treating cells as a single point feature rather than exploding them in the Advanced section of the General tab of the Configuration dialog, but we've noted recently that only works on DGN v7 files and not the newer ones. I plan to see about fixing that ASAP though as several people have noted it.

    I am at the ILMF trade show this week so it may take a little while.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • jubxiejubxie Global Mapper User Posts: 18
    edited February 2014
    Thanks Mike. Here is our custom units.def and a stock one. It's usually in: C:\ProgramData\Bentley\MicroStation V8i (SELECTseries)\WorkSpace\System\data (this is a windows 8 install, but I believe it's the same on 7).
    Maybe an option to define a custom units.def, otherwise defaulting to the above location (our custom one is server based, not local).
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