There is a checkbox that will create a simple collision if ticked. It’s on the top of the import window called “Auto generate collision”. To remove the collision double click the mesh in the content browser to open its properties. There is a collision section in the menu bar. Here you can remove the collision or add another simple collision. You can also move the collision around once you created it.
If the poly count isn’t too high would probably want to use the polygons itself as collision. This makes sense for building walls. To do this browse to the collision section in the mesh properties (not the detail panel) and set the collision complexity to use “complex collision as simple”. As DMHokie already mentioned.
This is a games engine so there are 2 types of collision
- simple collision is a box or another simple shape. This will be used for player collision and grenades, etc.
- complex collision is the actual geometry of the asset and is used for bullets, etc
That’s why it is named a bit confusing: use complex collision as simple, you want the player to use the complex collision instead of the simple collision. In ArchViz where there is no bullets or other effects it is ok to use complex collision. But if you have lets say a couch or table it makes sense to add a simple collision box or cylinder to it, especially if those are high poly.