Classification tools: Classify, Merge and Split Surfaces

You must classify walls (and optionally other features) to associate each with its building story before you can create a BIM. You should also merge surfaces to optimize the mesh. See Space to Create BIM Model .

View and Select Surfaces

1. To display the model, in Project Explorer, open the Classified Mesh Model folder and double click the mesh.

2. To see classifications clearly, select Color for classifications, and if the mesh has RGB or intensity texture, switch to Solid Color:
   
   and

3. The model is color-coded by auto planar classification, as indicated in the Classification window in the bottom right, which initially shows the classifications for the Site (the highlighted row):
   
   

4. Select one or more mesh model surfaces to classify as a specific IFC element in a specific story. Use a combination of the Split Surfaces 3D selection box and manually selecting individual surfaces or groups of surfaces:

   • Select a single surface: Ctrl+Click.

   • Select multiple surfaces:

     • Ctrl+Click each surface.

     • Click the Split Surfaces Tool button in the Classification panel to use a 3D selection box for splitting surfaces.

     • Click Rectangle Select and holdCtrl to drag select.

     • Click Polygon Select and Ctrl+Click to define nodes of a polygon selection.

   • Deselect: Ctrl+Click individually, or from the right click context menu, select Clear Selected Geometries.

Classify and Merge Elements

1. In the Classification window, click on the Story and IFC Element.
   If the IFC Element you want has not been defined, you can click Append to add it for this story of this model.
   
   

2. Click Classify or Merge:

• Classify
  Surfaces will be classified to the selected story and IFC element, but will remain individually selectable parts of the model.
• Merge
  Surfaces will be classified to the selected story and IFC element, but subsequently, selecting any part of the merged surfaces in the model will select them all.

Where possible, Merge multiple surfaces to create a single object. Removing unnecessary segmentation optimizes the model and file size for export.
Merging is permanent, so save frequently. If you make a mistake, you can close the model without saving the most recent merge and then reopen the model.

3. It's useful to have a noise element for people, furniture etc before classifying objects of interest. You can then uncheck that element, to hide it from view. As you classify other elements, you can hide them too:
   
   
   
   You can also right click on the selected row and select from the context menu: Hide in All Levels, or Show in All Levels, or Toggle in All Levels.

4. Repeat until you have classified all surfaces.

5. Click File > Save All.

 

Apply IFC Property Sets to Classified Mesh Surfaces

Once a surface has been classified into an appropriately mapped IFC layer, it is possible to add additional properties to the surface. These Property Sets use bSI standards for IFC. For more information, visit the Building Smart website.

⦁ Select on a surface that has previously been classified

⦁ Apply additional settings within “Surface Property Sets” window.

⦁ The surface properties available will depend on the IFC classification of the surfaces chosen. Surface property sets are only available for IFCBeams, IFCColumns, IFCCeilings, IFCFloors, IFCRoofs, IFCWalls and IFCWindows. The example below is for an IFCDoor.

 

Surface Flipping

To optimize the model for virtual reality, select surfaces to flip, so they are front-facing.You use the Surface Flipping Tool . See Surface Flipping and Triangle Winding.