Overlay DGN Files


  
 Applies To 
  
 Product(s):Bentley Navigator
 Version(s):08.11.09.293
 Environment: N/A
 Area: Open/Save
 Subarea: Overlay DGN
 Original Author:Darius Rimasauskas, Bentley Technical Support Group
  

 

 

 

 

 

 

 

 

Overview

Bentley Navigator uses the concept of overlay files. An overlay file is a V8 DGN file that references the original DGN or DWG file. It works as a container for review-specific content such as markup elements and saved views, while protecting the original file from modification.

When you open an ordinary (non-overlay) DGN or DWG file, Bentley Navigator creates and opens a temporary overlay DGN file. If you modify this overlay file and try to close or switch to another file, you are prompted to save the changes to a permanent overlay file. However, when you close the overlay file without doing any modifications, it is deleted.

Bentley Navigator opens existing overlay files directly. It does not create an overlay over an overlay.

Existing RDL or _redline.dwg files are treated like any other DGN/DWG files; an overlay is created for them.

When you open an ordinary DGN or DWG file, Bentley Navigator does not automatically search for a corresponding overlay file. For example, say a folder contains both test.dgn and test.overlay.dgn. If you open test.dgn, Bentley Navigator creates a temporary overlay file referencing test.dgn, ignoring the existing test.overlay.dgn. To open the existing test.overlay.dgn, you must explicitly select it.

Overlay File Format

The overlay file is always a V8 DGN file, regardless of whether the reviewed file is a V7 DGN, V8 DGN, or DWG. Overlay file names must have the overlay.dgn extension.

Using i-models

An i-model is a container for multi-discipline information published from known sources in a known state at a certain point in time. The i-model combines all the graphics and business data intelligence, as defined by the design application, into a single deliverable container for distribution. Because an i-model optimizes the business data, the result is decreased file size and easier navigation. An i-model contains links back to the original source data from which the i-model was derived, facilitating the life cycle review workflow.

Any application that can open a DGN file can open an i-model file. It is a read-only file, which prevents any corruption to the source file and it keeps the information secure. Since the i-model shows the design at a certain state, it is useful for version control and iterative workflows. The i-model is designed for information reuse; it can be published into standard formats like PDF and XML. An i-model always has the I.DGN extension.

Bentley Navigator can open and view an i-model. To publish an i-model, use Bentley i-model Composer, MicroStation, ProjectWise Dynamic Composition Service or other Bentley product.

If you attempt to open a file other than an i-model, you get an alert box telling you that “*.DGN is not an i-model. Do you want to open it anyway? An i-model loads faster and uses less memory than a DGN or DWG file. Use ProjectWise Dynamic Composition Service, Bentley i-model Composer, or other Bentley products to publish an i-model.”

When using an i-model published in Bentley i-model Composer (SELECTseries 1) from a DGN V7 file, you can encounter a problem with the color overrides. If so, republish the i-model using a later version of Bentley i-model Composer.

Difference Between Overlay and RDL File Contents

The biggest difference between overlay and RDL files is that overlay files do not duplicate as much information from the reviewed CAD file as RDL files. An RDL file is closer to a copy of the original CAD file with the graphical elements removed (and references to the original added). Whereas, overlay file contains a minimal amount of information copied from the original (while also adding a reference to it).

The reason for the differences is that the overlay file is intended to contain only review-specific content such as markup elements and saved views. For example, the overlay file does not need the full set of levels from the original file, because those levels are needed for modeling. Markup elements need not reside on modeling levels. They can reside on the overlay´s default level, or on some special “markup” or “review” level. The same type of reasoning applies to other modeling data like dimension style tables, color table, and so on.

There is also difference in the model handling of RDL files and overlay files. For example, a DGN has three models: “default,” “secondary,” and “layout,” with “secondary” being the active model. When Navigator 8.9.x or Bentley Redline creates an RDL file from that file, it copies all three models into the RDL file, with each model referencing its counterpart in the original file. On the contrary, when Bentley Navigator creates an overlay file from that file, it copies just the active “secondary” model.

Overlay File Creation

When Bentley Navigator creates an overlay file for a DGN or DWG file, a temporary file is created in the temp folder location designated by your system. By default the file name is original-base-name.overlay.dgn. For example, if the original file is named test.dgn, Bentley Navigator creates test.overlay.dgn. If the file with same name already exists, that means if another Bentley Navigator instance is running, or that some operation is trying to create a new overlay when one is already active, Bentley Navigator appends a sequence number (test1.overlay.dgn). If the original file´s base name ends with a digit, an underbar is appended followed by a sequence number. For example, if the original file is named 123.dgn, Bentley Navigator will create 123.overlay.dgn, then 123_1.overlay.dgn, then 123_2.overlay.dgn, and so on.

Item Sets and Overlay File Creation

If you create an overlay file from a DGN that contains item sets, these items sets are copied into the overlay so that you can access and use them.

Overlay Support for Embedded Linked Files

When you open a packaged file with embedded linked files for review in Bentley Navigator, an overlay is created with a model for the active model of the package root. If you try to follow a link to open an embedded file from the same reviewed package file, the same overlay is retained to be used for reviewing the embedded file with a new model added to overlay the embedded file. If you then switch between the embedded and package root files (for example, by following the design links) the existing models of the overlay are activated respectively.

Overlay File View Setup

When you open an ordinary DGN or DWG file, with a 2D model displayed, the view opens using the last saved view setup of the original source file.

With 3D models, Bentley Navigator sets up View 1 to show the Isometric, fitted, smooth-shaded, camera view of the model. Other view settings used are the clip front and clip back are off, scene lighting is off, Constructions is off, and visible and hidden edges are off.

However, you can set the MS_AUTO_VIEW_SETUP configuration variable to 0 to allow Bentley Navigator to open the published i-model using the last saved view setup defined in the source file, rather than the default setting.

For an existing overlay file, the overlay file's last saved view setup is opened.

Viewing a CAD File

You can use Bentley Navigator as a viewer.

To View a CAD File

  1. Open a DGN or DWG file in Bentley Navigator.
    A temporary overlay file is created on the local disk.
  2. View, navigate and modify the file as desired.
  3. Click File > Close.
  4. In the alert message to save changes to the file, click No.
    The temporary overlay file is deleted.

Reviewing a CAD File

  1. Open a DGN or DWG file in Bentley Navigator.
    A temporary overlay file is created on the local disk.
  2. View, navigate and modify the file as desired.
  3. Click File > Close.
  4. In the alert message to save changes to the file, click Yes.
  5. In the Save As dialog, save the file to the appropriate folder.

Alternative Method — To Review a CAD File

  1. Open a DGN or DWG file in Bentley Navigator.
    A temporary overlay file is created on the local disk.
  2. View, navigate and modify the file as desired.
  3. Click File > Save or File > Save As.
  4. In the Save As dialog, save the file to the appropriate folder.

To Make a Follow-up Review of a CAD File

  1. Open an existing overlay file in Bentley Navigator.
  2. View, navigate and modify the file as desired.
  3. Click File > Close.
    The changes are automatically saved.