# BIM models

A BIM model is a 3D model of a building or other built asset such as a bridge, road, or pipeline. BIM models are used in the planning, design, construction, and maintenance of the built asset. In Trimble Access, BIM models can be used for surveying fieldwork including stakeout, cogo calculations and measuring points.

IFC and TrimBIM files are not supported on 32-bit Trimble controllers running Android. These controllers are the TCU5 controller and the TDC600 model 1 handheld.

Supported file types

Trimble Access supports the following BIM model file types:

- Drawing (.dwg) files created using Autodesk AutoCAD software.

- IFC (Industry Foundation Class files) in the .ifc or .ifczip file format.

- Navisworks (.nwd) files created using Navisworks software.

- SketchUp files (.skp) created using Trimble SketchUp software.

- TrimBIM (.trb) files, which are a smaller, more efficient alternative to IFC.

DWG and NWD files are not supported when stored directly to an Android device. When using Trimble Access on a controller running Android, upload DWG and NWD files to a Trimble Connect project using Trimble Connect for Windows. The files are automatically converted to TrimBIM files in the cloud. When you download the project to the controller, select the Settings tab and select the Download as TrimBIM check box. This setting is not required when using a controller running Windows, but may still provide better performance. For more information, see Cloud settings for data sync.

Trimble Access supports the reading of standard AutoCAD entities from DWG files. Some CAD applications, for example Civil 3D, use AutoCAD extensions to create 3D objects which may not be supported by Trimble Access. Using a DXF file may be better than trying to use DWG, or you could try converting a Civil 3D drawing to a standard AutoCAD DWG format. For more information, visit Autodesk's Knowledge Network to learn how to convert Civil 3D drawings to standard AutoCAD format.

Viewing BIM models in the map

To display a BIM model in the map, tap in the map toolbar to open the Layer manager and select the Map files tab. Tap the BIM model file once to make it visible (), and tap it again to make items in the file selectable (). For more information, see Managing map file layers.

To make only some layers visible or selectable, tap the arrow next to the file name and then tap each layer once to hide it, or twice to make it visible but not selectable. Tap the layer again to make it visible and selectable. Note that for IFC files, layers are named based on the IFCPRESENTATIONLAYERASSIGNMENT attribute in the IFC file.

To see more clearly inside a model, use the Limit box to exclude parts of the model such as floors or exterior walls. See Limit box.

To easily show only some items in a BIM model regardless of the BIM file or layer they are in, use the BIM toolbar. See Hiding and isolating items in BIM models.

Objects in BIM models can be displayed as solid objects, or you can make the object semi-transparent. To make the object more transparent, tap and select Transparency. In the BIM models group box, use the Transparency slider control to change the transparency of the BIM model.

You can also display the model as a wireframe rather than as a solid object. Displaying as a wireframe enables you to see more detail in the BIM model and makes it easier to select the correct points or lines for stakeout. To view the model as a wireframe, tap and select Transparency. In the BIM models group box, select Wireframe in the Display field. If you frequently switch between wireframe and solid views, you can configure a function key on the controller to switch between the wireframe and solid view of the BIM model. For more information, see Map data transparency.

To rotate the BIM model in the map, tap and then tap the map and drag to rotate the view. The icon in the center of the map indicates the point of orbit.

To improve performance, the map may not display very small items or details until the map is zoomed in to an appropriate zoom level.

Viewing BIM models in the Video screen

If the controller is connected to a Trimble SX10 or SX12 scanning total station, you can view data from BIM models overlaid on the video feed. To show or hide individual files, or individual layers within a file, tap in the Video toolbar to open the Layer manager and select the Map files tab.

To display the model as a wireframe, a solid object, or both, in the Video screen tap and then select Settings.

Working with BIM models

To select an item from a BIM model, tap it in the map. The item you have selected is shown in blue. To select multiple items, press the Ctrl key on the controller and then tap the items in the map to select them.

Items in a BIM file cannot be selected using Rectangle selection or Polygon selection.

You can select items in the BIM model from the map and then use them in other software functions, for example to perform a Cogo calculation, create a surface, or stake out. Tap an item in the BIM model to select it.

You can select vertices, edges, curved edges (polyedges, such as the rim of a cylinder), or surfaces.

To select a surface the BIM model must be shown in the map as a solid object, not as a wireframe.

You can choose whether selecting surfaces in the map selects Individual faces or selects the Whole object. To change the Surface selection mode, tap and select your preferred Surface selection mode. See BIM model selection mode.

To measure to a surface in a BIM model, select the surface in the map and then select Measure to selected surface from the tap and hold menu. This is useful in determining the perpendicular distance from the physical surface to the design.

When you use a vertex, edge, curved edge, or surface from a BIM model in a Cogo calculation, during stakeout, or to create a point in the job, Trimble Access copies the attributes of the object from the BIM model and stores them with the point or polyline in the Trimble Access job.

To review BIM model attribute information for objects in a BIM model, select the items in the map and then tap Review. If you selected more than one item, select it from the list and tap Details.

Cogo calculations using BIM models

To compute the center point of a surface in a BIM model, select the surface in the map and then select Compute center point from the tap and hold menu. This is useful to find the center point of a bolt or cylinder so you can then stake it out. See Compute center point.

To compute the centerline of any tube-like item in a BIM model, such as a pipe or cylinder, select it in the map and then select Compute centerline from the tap and hold menu. The software computes a polyline that runs along the center of the item. See Compute centerline.

To compare the scan point cloud of an as-built surface with whole objects or individual faces in a BIM model, use the Surface inspection Cogo function. See Surface inspection.

Staking from a BIM model

You can select vertices and stake them as points or you can select edges, curved edges, or grid lines and stake them as lines directly from the BIM model. See Staking from the map.