MicroStation V8 Cell


What is a cell library in V8?

A cell library is any DGN file.  Within a DGN file, each model can be placed as a cell unless specifically disabled in the model properties.  The elements of a cell can be edited directly by opening up the appropriate cell library in MicroStation, changing to the correct cell model using the model manager (File->Models), and editing the elements.

What is the cell origin when placing a Model as a Cell?

Usually the origin is (0,0,0) in the model that is being placed as a cell. For example, an ellipse is created whose center is (0,0,0). When that model is placed as a cell, the cell origin is in the center of the ellipse.   This is the recommended way to set up cell libraries.  However, to support DWG blocks, the insertion base (INSBASE) is used as the origin if that is set.  Similarly, if the DGN model has a global origin set, that will be used as the origin.

How do I change the origin of a cell model?

Since the (0,0,0) point of the model is the origin of the cell, the easiest way to move the cell origin is to move the elements relative to this point.  The procedure is simple:

Why is it that I cannot open up any of my converted cell files (from V7 to V8) and see anything?  All I get is blank, blank, blank.

Each cell is stored in a separate model in the design file.  When you load up a cell library as a DGN file, it starts in the default model, which is blank.  Use the model manager (file->models) to access the different cells/models by name.  Notes that by default, viewgroups are not created for each of the cells; therefore the cells will not appear in the viewgroups combo box.

Why do the colors change when I place a cell that I converted from V7?

A cell library in V7 did not have an associated color table.  In V8, since cell libraries are DGN files, they do have an associated color table.  Cells, like elements copied from references, try to find the closest RGB color match that makes the placed cells look the same as the ones in the library.  This behavior can be turned off using the preference under Reference for "Remap Colors on Copy," causing the color number to remain the same as the element is copied.  However, since many users have a color table preference, it is usually easier to attach the correct color table to the cell library once it has been converted.  If the color tables are the same between the cell library and active file, no remapping will occur.   Another option is to set up a seed file for the conversion; see Question 5: What seed file is used when upgrading V7 cell libraries?

What seed file is used when upgrading V7 cell libraries?

Since 2D and 3D cells can coexist in the same file, no seed file is needed for the creation or upgrade of cell libraries.   However, it may be convenient to choose a seed file that contains standard levels or color tables.  Simply set the configuration variable MS_CELL_SEEDFILE to point to the file that you wish to be your seed.  This file will be copied to the new location and the cell models will be added to it.  It is recommended that the seed file only contain a default model to avoid model name conflicts with the cells.  This configuration variable also applies to new cell library creation from the Cell Library dialog.

How do I map level numbers to level names when importing a cell library?

This is handled exactly the same way as when importing a V7 DGN file.  See http://selectservices.bentley.com/technotes/faqs/6214.htm#16.

How are levels handled when placing a cell?

Levels are resolved by name from the cell library.  If a level with the same name exists in the active file, then the element is put on that level.  If the level does not exist, it is copied from the cell library at the time when the cell is placed.

If the same level exists in both the cell library and the active file but the levels have different symbology, the differences are ignored.  Therefore if an element uses ByLevel symbology, it may look different between the two files.

What is relative level placement?

The relative toggle on the Place Active Cell tool allows the user to place the cell on levels relative to the active level.  The effect of this is to match the lowest level found in the cell to the active level and then change all the levels of the elements in the cell to be the same level relative to the lowest/active.  In other words, if a cell resides on levels 10, 12, and 15 in the cell library, and is placed relative on active level 15, it will reside on levels 15, 17, and 20 in the active model.

In order to do relative placement the level numbers in both the master file and cell library are used.  However, in V8, there is no requirement for all level numbers to exist.  Therefore, if a cell is to be placed relative, all levels that it requires must exist in the master file.  If not, you will get an error.  Using the above example, if there is no level number 20 in the active file, then the cell will not be placed.

How do I merge cell libraries?

Merging cell libraries is done through the model import command.  Open up the cell library that will receive the cells.  Then start the model manager (File->Models) and select Import Models.  Choose the file from which the cells are to be copied.  Then multiple-select all the cells that are desired and click OK to merge the cell libraries.

How do I place DWG files as blocks?

You can place DWG files as blocks or cells in your DGN or DWG file.  First you must set up MS_BLOCKLIST to point to the list of files that you wish to place as cells.  MS_BLOCKLIST may contain full file names or directories such as "d:\dwgblocks\*.dwg".  Once this configuration variable is set up, then click the "Display All Cells In Path" toggle in the cell library dialog (Element->Cells) to display the DWG files in the list of cells.  Once selected for placement, the DWG file behaves exactly as a cell.

Can I use my V7 cell libraries in V7 work mode?

It is not possible to use MicroStation/J, MicroStation SE, etc., cell libraries in V8 in their native V7 format even in V7 workmode. Once you attach a cell library in a V8 design session, it is automatically upgraded to V8 format and a backup is saved to MS_BACKUP (or MS_TMP if MS_BACKUP is not defined). If you wish to continue using a cell library with V7, you will need to maintain the cell library in V7 and upgrade a copy to V8 as needed. This does not affect cells placed in a DGN file, which will save to V7 just fine.

Can a cell library contain both 2D cells and 3D cells?

Yes.  A DGN file can contain both 2D and 3D models, and a cell library can contain both 2D and 3D cells.

What does the True Scale setting do when I place a cell?

The True Scale setting automatically compensates for models that have different unit systems.  All elements will be resized accordingly.  For instance, if a cell is created that is 1 meter wide, when it is placed in a different file with feet as master units, it will be 3.2808 feet.

What about cell index (CDX) files?

CDX files are no longer needed in V8.  You may delete them.

How can I change point cells to normal cells?

A point cell can be changed to a normal graphic cell using the model manager.  Open the cell library that contains the cell you wish to change as a DGN file in MicroStation.  Start the model manager (File->Models) and select the cell.  Click on the "Edit Model Properties" icon.  The Cell Type option button will allow you to change the type of the cell.

Can I save a V8 Cell Library to V7 format?

No.  If you want to maintain a cell library in both V7 and V8 formats, you must maintain the V7 cell library and upgrade a copy to V8 when it changes.

How do I create a cell library from shared cells in a DGN file or blocks in a DWG file?

The keyin EXPORT CELLS SHARED [destinationCellLibraryName] in MicroStation V8.1 provides this ability. For example, to export all the shared cells in the current file to a file called blockCellLibrary.cel, use:

                EXPORT CELLS SHARED c:\myDgns\blockCellLibrary.cel

This keyin can be used in conjunction with Utilities > Batch Process to rapidly convert all the shared cells in one or more files into a single cell library. Please refer to MicroStation's online documentation for more information on Batch Process.

Can I place shared cells or blocks from a different file?

As of MicroStation 8.1, shared cell definitions (or blocks) can be placed from the active cell library using the normal Cell Library dialog (elements > cells).  The attached file can be either a DGN or a DWG.  These cells are designated with the letters LbSh (for Library Shared) in the Where column of the Cell Library dialog. 

By default this capability is enabled; however, it can be disabled by turning off the CAPABILITY_SHAREDCELLS_FROM_ATTACHED_LIB capability.

How are nested cells handled in V8?

In V8, a reference is the equivalent of a nested cell in previous versions.  When placing a cell, all references attached to that cell including any nested references will become individual nested cells.  Any references which are not displayed will not be part of the resulting cell.

If the references are to models in files other than the cell library and the file containing the reference is not found, the cell will still place but it will be missing the data from those references.  So it is recommended that nesting be done within the same file.

See also

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 Original Author:Bentley Technical Support Group