MassMotion – Model preparation with SketchUp
When creating models in SketchUp for MassMotion, one thing you do need to be careful of is SketchUp’s helpful habit of joining any lines or surfaces that cross, because MassMotion needs them to be kept separate. To ensure that the model does not import as one big lump you need to group every object as soon as you have drawn it. This is a simple operation as you just double click on the surface to select it and the bounding lines, then right click and select Make Group. You can see your progress in the Outliner dialog.
If you need to edit anything in a group, you can double click on it to enable editing; double click somewhere else on the screen to return to the normal view. If necessary, you can also explode a group back to normal SketchUp elements.
While you can name these groups, the names are not carried through into MassMotion and thus only name them if you find it useful within the SketchUp environment. Likewise colours and materials are normally left behind.
Most SketchUp templates include a figure. It can be useful to leave them in the model when exporting to MassMotion as they will appear next to the MassMotion avatars, giving you an instant check that the scaling between the two programs is correct.
For complex models, you may find it helpful to use SketchUp’s layering, as this will make it easier to export the floors, links, etc. into separate files for easier categorisation in MassMotion.
There are several file formats available for the export, but I find that the .fbx and .ifc formats work well. FBX caries just the geometry information, while IFC also contains metadata saying what type of objects the graphics represent. To use IFC you need to apply IFC properties to the objects, which will make the subsequent generation of MassMotion objects easier following import. Do this, select the grouped object and in the Tray > Entity Info set the Type. If no categories are currently included in the model the Model Info > Classifications dialog will open. Click Import and choose IFC 2×3.skc. Close the Model Info dialog and select the desired IFC type. See the help file Reference > User Interface > Generating Objects from Geometry > Generating from IFC for the list of IFC types that MassMotion recognises.
It is important to set the following export options:
- units = metres (MassMotion only uses metres and this will scale the SketchUp units)
- swap axes, Y is up (SketchUp has the X and Y axes horizontal while MassMotion follows the Softimage convention of putting X and Z horizontal)
- export selected only (this is useful rather than essential, as you can subsequently export just any changes rather than the whole model)