The Attach iTwin tool in MicroStation is available as a part of the Collaboration tools, and lets you attach an iModel as a reference in a DGN. Tools in the Collaborate ribbon tab in MicroStation bring together collaboration, synchronization, and issue resolution tools for better coordination among team members.
In MicroStation CONNECT Edition Update 17, Attach iTwin tool includes some improvements.
1)Search allows you to search for an iModel by name. Filter allows you to filter your search by Name, Owner, and Downloads State, and Ascending or Descending order.
2) Back takes you back to the Attach iModel as Reference section of the dialog
3)Attach iModel as Reference dialogue has a new model-tree dialogue, that contain more controls and allow for greater flexibility while attaching iModels as reference.
You can check models you want to display (attach /detach), snap, locate and apply transparency.
4) Filter lets you filter the list of models based on values you enter.
5) When data in a model uses a Geographic Coordinate System, MicroStation can easily reference data that is also geographically aware into the model. While attaching an iModel, in MicroStation, if both the reference iModel and the active model have a GCS, the Attach iModel as Reference dialog enables the AEC transform option.
The AEC Transform option in the Attach iModel as Reference dialog, will perform an AEC Transformation to align the GCSs in the iModel and the active model during attachment.
Note: the AEC Transform option will be enabled only if the reference iModel and the active model have a GCS. If both or either of the model is missing GCS information, this option will not be enabled in the Attach iModel as reference dialog. If both the reference iModel and the active model have the same GCS then an AEC Transform is not needed.
With an AEC transform, MicroStation calculates the linear transformation to give the best approximation to the results. The approximation is acceptable for smaller-scale data, such as most man-made structures that occupy less than a square kilometer.
With the reference model and the active model GCSs aligned it will be easier to place and manipulate elements in a relative coordinate system.
Note: AEC Transform will also work for iModels with a GCS with Helmert transformation in the coordinate system.
6) Allow Referencing the active model allows self-referencing of same model from iModel to the active model while attaching. This option is enabled if the active model is previously synchronized with the iModel.
7) Update iModel Attachment is enabled when the attached iModel is updated in the iModelHub and updates the attached iModel for any changes made to it in the iModelHub.
(iModel before updating) (iModel after changing , synchronizing and updating)
8) There is a drop-down menu at the top right-hand side of the dialog which lists all the attached iModels.