I made a concave house model. When I import it to Unreal Engine it generates a simple box collision that covers the full mesh. I need a collision that only covers the walls. How can I generate one or edit the collision? (I'm using Maya.)
There's a couple things you can do. What's considered the best practice is to make your own collision bodies to import with the asset. I forget the exact file format but your basically just using boxes or other basic shapes to create your physics bodies. The other method is letting ue4 generate more thorough physics bodies for your mesh though probably not the most optimized way of doing it. I believe it's called "Convert boxes to Convex"(or "Auto convex collision"). Here's an image.
There's three main ways you can do it - you can either open the house as a blueprint and add a bunch of "box collision" componenents, and edit them by hand. Another thing you can do is open the house's mesh and (as the previous commenter said) add box collisions. The result will be more or less the same.
The last way you can do it, is to also open the house's mesh. Then, you can use the window in bottom right. It should have a button "create convex collision". You can choose how many colliders you want and how complex they should be with the sliders. It can take few seconds, and the results might not be satisfying - but it will be fully automated. If that's not enough, you can check the option "use complex shapes as simple" - that should totally cover the house, however it will be the most costly.