When starting a new project there are two methods for bringing 3D models into SYNCHRO 4D:

• 3D importers within SYNCHRO 4D. This is the traditional import method that existing SYNCHRO Pro users are accustomed to and the only method available when working with private projects (non-cloud hosted, standalone .sp files), and when upgrading an existing private project or SWP project. Supports 40+ Bentley and 3^rdparty file types.
  
  
• iModel Connections on the Web and/or iTwin Synchronizer desktop app. This is a new offering that provides better support for native Bentley models and other benefits but supports fewer 3^rdparty file types.

The two methods are mutually exclusive. The method to be used on the project must be chosen when the project is first set up and will be used for the duration of the project. Therefore, it is important to understand the alternative methods in order to make the best decision for your project.

Method 1: Traditional 3D imports in 4D

After setting up the 4D project in SYNCHRO Control, user opens the project in SYNCHRO 4D and selects File > Import to import 3D, IFC, or Synchro Project (.sp and .spx). The 3D importers support an extensive list of file types including .dgn and .i.dgn, .dwf and .dwfx, .fbx, and .skp. The full list of file types that can be imported can be found here. The Synchro Pro plugins also allow export from MicroStation (.dgn and .i.dgn), Revit (.rvt), and Navisworks (.nwf, .nwc) to .spx which can be imported to SYNCHRO 4D using File > Import > Synchro Project.  It is possible to import from files stored locally or in ProjectWise.

When multiple models are imported, their location can be edited after import if needed to create a federated model (although it is preferable to do this in the model source program). After import to SYNCHRO 4D, the models are automatically synchronized to the connected iModel so that they are available to other SYNCHRO 4D users as well as in SYNCHRO Control and SYNCHRO Field.

When the source models are updated, the model should be re-saved or exported in the same file format as used to import it and then synchronized from by going to Navigator > External Data in SYNCHRO 4D. Synchronization is performed on-demand by the user.

When this method is chosen, users may also import equipment and logistics models from the SYNCHRO equipment library or another source. Simple objects (box, cylinder, sphere, and polygon extrusion) can be modelled in SYNCHRO 4D, for example to represent temporary objects and material laydown zones. Translucent workspace objects can be modelled from the bounding boxes of 3D objects to help with workspace planning.

All objects imported, created, and edited in SYNCHRO Pro are synchronized to the iModel. When this method is chosen, users perform all import and synchronization of 3D models in SYNCHRO 4D (desktop). After the initial set-up in SYNCHRO Control, there is no requirement to return to SYNCHRO Control (except to manage users/permissions). Of course, users may wish to access all the additional rich project management and 4D review features available in Control, but they don’t strictly need to access Control to perform the 4D planning work.

Method 2: Create iModel by using iTwin Connections

If you are already working with Bentley iModels, or are interested to leverage the iModel technology, you can use one of the workflows below to bridge into an iModel. After the iModel is created in a Control project with 4D Scheduling service enabled, you have two choices for how to add the 3D models to the iModel. The two methods can be used interchangeably:

• Web: Use instant-on iTwin Connections (accessible via SYNCHRO Control). Works with models stored in SYNCHRO Control or ProjectWise
• Desktop app: Use iTwin Synchronizer, a desktop app, to synchronize models to iModel. Works with models stored locally

If your project models are authored primarily in native Bentley products (e.g. MicroStation, OpenRoads) iTwin Connections may be a good choice for your project. iTwin Connections provide better support than SYNCHRO 4D importers for native Bentley products, higher fidelity of User Field data, and a possibility for quicker turn-around on improvements. Bentley iModel bridges also offer SYNCHRO users the option to bridge in .vue format without having to be passed through another product (i.e. Navisworks) as was required in the past to import .vue files to SYNCHRO Pro; for .vue files the best practice is to use the web iModel Connections (not desktop iTwin Synchronizer or SYNCHRO Navisworks plugin).  The Connections also support Revit (.rvt) files and IFC among others. A full list of supported applications and file formats can be found here.

After the model is bridged into the iModel using the web Connections or desktop iTwin Synchronizer app and the iModel is set up as a 4D collaboration project in Control, the project can be opened in SYNCHRO 4D and the schedule can be added or imported as usual.

 If the geometry source is from iModel Connections, the following features are disabled in 4D:

• Import > 3D / IFC / Synchro Project
• Create > 3D (sphere, cylinder, box, extrusion, text, textured plane)
• Create > Workspace
• Edit > Color
• Edit > Manipulators (NOTE: Edit as Assigned>Manipulators are still available)
• 3D Properties > Transform

This means that ALL geometry modifications MUST be made in the original model and synchronized to the iModel using the bridges. Equipment, temporary objects, and workspaces must be added to the original models or bridged in as separate models.

If the source of 3D is from iModel bridges, users must always stay connected to the project and offline; changes cannot be merged by reuploading an .sp to Control. [A workaround may be possible in a case-by-case scenario.]

When the models are updated, synchronizations are performed via the iTwin Connections or Synchronizer app. These tools have the added benefit of allowing you to schedule model synchronizations of model updates on a regular basis compared to the traditional method of on-demand synchronization in SYNCHRO 4D when the model source is uploaded via the 3D Importers in 4D. Using the iModel Connections feature to schedule synchronization means that you can ensure the 3D model is being regularly updated with the latest changes, can schedule it for out of office hours to ensure it does not interrupt other users work waiting for the new models to download, and you will save time since you no longer need to perform the synchronization on demand and wait for it to complete.

Detailed directions for setting up the iModel using the instant-on iTwin Connections with Control are here. More details on the different ways to sync your data to an iModel can be found here.

Comparison

A comparison of the 2 workflows is below:

Model source:	3D Importers in 4D (desktop)	iModel Connections (web or desktop)
Model storage	Models can be imported from local storage or from ProjectWise.	Use web Connections for models stored in SYNCHRO Control or ProjectWise. Use iTwin Synchronizer desktop app for models stored locally.
Add 3D models	Import files directly in SYNCHRO 4D. Over 50 file types supported.	Bridge model files into the iModel using iTwin Connections online (accessible via SYNCHRO Control).
Synchronize model updates	Manually synchronize each file in the SYNCHRO 4D UI on demand.	Schedule automatic synchronizations of the latest model files in the specified model storage location or synchronize on demand using iTwin Connections online (accessible via SYNCHRO Control).
Equipment & Logistics models	Can be downloaded from SYNCHRO equipment library. Import directly to 4D in the same was any 3D model.	Can be downloaded from SYNCHRO equipment library. Bridge into the iModel using iTwin Connections online (accessible via SYNCHRO Control). 3D Importers are disabled in 4D when iModel is the source of 3D.
Workspaces	If created in the source model, can be imported directly to 4D. SYNCHRO Workspace objects can be created in 4D from the bounding boxes of 3D objects or by extrusion.	If created in the source model, Bridge model files into the iModel using iTwin Connections online (accessible via SYNCHRO Control). Create Workspace tools are disabled in 4D when iModel is the source of 3D.
Subdivide model	Subdivisions can be performed in SYNCHRO 4D after import or can be created in the source program before import/synchronization./ SYNCHRO Modeler cannot be used with projects where 3D importers in SYNCHRO 4D are used.	Subdivisions must be performed in the source model or in SYNCHRO Modeler which is included with the SYNCHRO 4D license. 3D Subdivision is disabled in 4D when iModel is the source of 3D.
Edit model	After import, it is possible to edit the color, translation, rotation, and scale of 3D objects in SYNCHRO 4D. The assigned translation, rotation, and scale of 3D resources can be edited.	All model edits must be performed in the source model program. Edit Manipulators are disabled in 4D when iModel is the source of 3D. The assigned translation, rotation, and scale of 3D resources can be edited in SYNCHRO 4D. Edit as Assigned manipulators are available – these affect only the transformation of the 3D resources during the assigned task(s).
Create basic geometry	Simple geometry can be modelled in 4D: sphere, cylinder, box, extrusion, text, textured plane.	All new geometry must be added in the source model program. Create tools (sphere, cylinder, box, extrusion, text, textured plane) are disabled in 4D when iModel is the source of 3D.

No matter which method you decide to use for your project, any additional model imports and all subsequent synchronization of models will need to follow the initial setup method. If 3D importers in SYNCHRO 4D are used, all subsequent imports and synchronization will need to be performed within 4D using the traditional 3D imports in 4D’s UI. If iTwin Connections are used, all subsequent imports and synchronizations need to be performed using the iTwin Synchronizer app or web-based iTwin Connections. Therefore, it is important to consider up front which method will be best for your project.

Create iModel (for existing projects)	Create iModels (for projects created after Jan 15)
Create iModel using an .SP file Create iModel from ProjectWise Design Integration Create iModel from iTwin File Service (Control Documents) Create iModel from iTwin Synchronizer	Create iModel using an .SP file Create iModel from ProjectWise Design Integration Create iModel from iTwin File Service (Control Documents) Create iModel from iTwin Synchronizer