3D Models

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Scaling

Unity works with arbitrary units. The default physics work on the assumption that one unit is one meter. The VR-setup also assumes that one unit is one meter. Therefore all models should be designed in such a way that one unit is equal to one meter.

Here is a checklist for correct model scaling:

• The model was created in life size
• The model is exported to FBX with a scaling factor of one
• It is imported into Unity with a scaling factor of one
• It is placed in a scene with a scaling factor of one
• The model has the correct size for a VR-Player with a scaling factor of one

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Rotation

Unity uses a left-handed coordinate system. Blender uses a right-handed one. Therefore a conversation is needed when importing from Blender to Unity. Models should be created in such a way that they respect the rotation conventions.

Blender rotation convention:

Direction	Color	Interpretation
Positive X	Red	Left
Positive Y	Green	Backwards
Positive Z	Blue	Up

Unity rotation convention:

Direction	Color	Interpretation
Positive X	Red	Right
Positive Y	Green	Up
Positive Z	Blue	Forward

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Origin

The origin of a model should be chosen to make it as easy as possible to place the object in a scene. For example, if the object is a lamp that is mounted to the ceiling the origin should be in the middle of the part of the lamp that touches the ceiling. If the object is a door the origin should be at height 0, forward 0 and in the middle of the width, so that the door can be easily placed to touch the wall and floor.

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Importing

In order to prevent import issues during version upgrades all models should be included via FBX. Blender and other 3d-model files should not be placed inside the unity folder.

TODO: https://www.immersivelimit.com/tutorials/blender-to-unity-export-correct-scale-rotation

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