Guide to Using DWG and Other Formats
Guide to Using DWG and Other Formats
Guide to Using DWG and Other Formats
Guide to Using DWG and Other Formats
Guide to Using DWG and Other Formats
Guide to Using DWG and Other Formats
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Whether you open a DWG file in MicroStation, attach a DWG file to a DGN file, insert a DWG file into a DGN file as a cell, or save a DGN file to a DWG file, it is important to keep the units consistent.
When you save a DGN file to a DWG file, use the Save as DWG/DXF Options dialog box to set the linear units of measurement to use in the AutoCAD file.
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Save As DWG/DXF Options dialog box General tab Basic options | |
Although MicroStation allows you to select a different unit system at any time without changing the actual size of the model geometry, AutoCAD does not provide a convenient method for altering units. Therefore, it is important that you select the correct output units. If you select Master Units or Sub Units, MicroStation uses the Master or Sub units from the default model of the current file. Otherwise, you can select a specific unit system.
To check the model's settings, choose Settings > Design File. Select the Working Units category to see the Master Unit and Sub Unit settings.
When you open a DWG file in MicroStation, use the DWG Open Options dialog box to set the units options.
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DWG Open Options dialog box | |
The Units options provide MicroStation with information to determine the linear units to use, and thus the true size of the DWG geometry.
MicroStation's system for controlling units is very flexible, but it depends on knowing the true geometry size. Many of MicroStation's tools for dimensioning, placing cells, and referencing rely on the file units to work correctly. Unfortunately, MicroStation cannot always infer the file units in AutoCAD files. To accurately set the MicroStation Units options, you must understand the DWG file content and the standards used to create it.
AutoCAD uses two types of linear units that are specified by the LUNITS variable. DWG files with Engineering and Architectural units (LUNITS= 3 and 4) are implicitly English units (feet and inches), so their units are known. The other types — Scientific, Decimal, and Fractional (LUNITS = 1, 2, and 5, respectively) — do not imply a specific unit of measurement.
Beginning with AutoCAD 2000, INSUNITS system variable specifies units for Design Center blocks that are inserted into existing drawings. The INSUNITS variable allows for the type of automatic scaling that MicroStation performs when True Scaling is specified. Unfortunately, this variable does not exist in DWG files before AutoCAD 2000, and may be set inconsistently in files from more recent versions.
If the system variable INSUNITS is appropriately set, when you open the DWG file in MicroStation you can set the Units options to Design Center Units. This is the best way to ensure that units are consistent when you open a file in MicroStation.
To set the Design Center Units for a DWG file in MicroStation, use the DWG UNITS key-in to display the DWG/DXF Units dialog box, which lets you control the Design Center Units (INSUNITS) setting. Use the Save Settings command (File > Save Settings) to save the units setting in the active design file.
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DWG/DXF Units dialog box | |
Data in DWG files can be attached to the open file as references or cells. When you attach a DWG file as a reference, you can set options for units on the DWG Open Options dialog box. To do this, open the Attach Reference dialog box and click the Options button. Generally, you will get good results if you set both Units options to Design Center Units. If the system variable INSUNITS is appropriately set in AutoCAD, MicroStation can automatically interpret the DWG units.
When you insert a DWG file as a cell, the units settings are controlled by the DWG Open Options dialog box (File > Open, then click the DWG Options button). Again, it is generally best to set the Units options to Design Center Units.