How to set correct block unit scale when exporting to DWG?

ACAD users complain that the blocks in exported DWG from Microstation has undefined units so the block scale is not correct. when inserted.

The cells should be 2meters but are 0.003 meters in ACAD. If the units are fixed in ACAD block definition dialog then the blocks are correct.
Tried to set different design center units(key-in:dwg units, dwg insunits) in DWG seed or after export using Microstation but it didnt help.

  • It seems that INSUNITSDEFTARGET and INSUNITSDEFSOURCE values are wrong milimeters not Meters but not sure how to set this in Microstation.
  • You can set INSUNITSDEFTARGET and INSUNITSDEFSOURCE in a DWG seed file you use to save a DGN file as a DWG file and these system variables should stay unchanged.

    Block units are not currently set when a DGN file is saved as a DWG file. This is mainly because in MicroStation once units are set for a design everything in the design imply to be in the same units, including cells. When such a DGN file is saved as a DWG file the same implication is retained: a shared cell to be placed in the DWG file should scale the same way as it did in the DGN file. This implication works in ACAD as well with the DWG file saved from the DGN file. In ACAD, all blocks/cells still inherit the same DWG file units just like they did in DGN file.

    The only difference it would make is when a cell/block of different units is needed, for example inserting a block in Millimeters into the design center in Meters. The only problem is how we would know which block should use MM and which should use M when a DGN file gets saved as a DWG file. The source cells do not have units information, neither has DWG SaveAs Options a way to control individual cells in the file. However, if setting all saved blocks in the DWG file to use the design units is desired, I suppose we can add such a toggle in SaveAs Options. Would this option help though?

  • Thanks for sending us your test file! I think that I might have finally understood the issue you were facing: you(rather the recipient of DWG file) worked on an ACAD installation with INSUNITSDEFTARGET and INSUNITSDEFSOURCE set to different units than those in the DWG file. It turns out that I have misled you in believing that these two system variables can be set in a DWG seed file - they cannot. These are actually user preference settings in ACAD and are stored in the computer's registry, not in the DWG file as most of other system variables are. While in theory we can also change these registries as a DWG SaveAs option, it would only help you if you run ACAD on the same computer and logged in as yourself. Based on my understanding of your workflow you were sending your DWG files to someone else who did not use your computer, therefore such an option to change the registry offers little help to you nor to most users using MicroStation.

    When your ACAD user had these two system variables set to different units than the design center units in the DWG file you sent to him, he would get an unexpected scale when he inserted the block into the model. In this case, defining the units in the blocks makes sense, so that the ACAD user wouldn't have to change the system variable to the correct file units. We will consider adding this option in a future release of MicroStation.

  • From ACAD Help
    INSUNITS-Specifies a drawing-units value for automatic scaling of blocks, images, or xrefs inserted or attached to a drawing.
    Note: The INSUNITS setting is ignored when inserting annotative blocks into a drawing.

    Strange that even setting INSUNITS correctly didn't fix my test file as I understand this value should help. Maybe that is related to the fact that we have annotation cells in DGN so they are converted to annotative blocks?

    The issue is that we have cells in Meters but INSUNITSDEFTARGET and INSUNITSDEFSOURCE are in milimeters by default so the blocks are placed in wrong scale. According to ACAD help source content units value are only used when INSUNITS is set to 0 but it doesn't seem to be the case as even when INSUNITS units where set to 6 the blocks are in wrong scale.
  • That's right. A DWG file saved from DGN always has INSUNITS (aka design center units) set, Meters in your case. If your ACAD user has INSUNITSDEFTARGET and INSUNITSDEFSOURCE set to Millimeters, his block will be inserted at a scale of 0.001. He can certainly change his user preference to use Meters as a solution. Alternately if the blocks are in Meters, he'd get a scale of 1 without having to change his user preference. This is why I agree with your original request of an option to set units for all blocks from the source file units. It will save your effort of reminding your DWG file recipient to set his user preference correctly.

  • But according to ACAD help if INSUNITS are set then it shouldn't use other values. Also is it needed to set INSUNITS in DWG seed when converting from DGN or it is not used?
  • The INSUNITS referred to in ACAD help implies the "insertion units" of the block, not the system variable INSUNITS of the active file. in ACAD, when a file is inserted into another file, the file INSUNITS serves as the same "insertion units" of the xReference block. I guess for that reason they just simply call it INSUNITS, so both cases of block definition are covered.

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