When I controlled my character to stand on a rock, I noticed that he was standing in the air. I quickly realized that this was because the stone under the character’s feet was magnified many times (about 7~8 times), and simple collision could not provide an accurate collision volume. Therefore, I selected the stone instance and looked for a while in the Collision category of the details panel, but I didn’t see an option to change the collision complexity. As of the current version (5.5), is there a way to change the collision complexity for a specific static mesh instance?
You can’t do it per instance since collision is stored in the static mesh asset itself.
What I would do is try and use the convex collision generator and try to refine it to make it as close as possible.
If you scale it uniformally, it shouldn’t give any issues. Non uniform scaling might though.
I have already done this before posting this, and I have turned the precision up to max. If what jkinz3 said is true, I guess the only solution is to duplicate the static mesh asset as a new asset, and then set the collision complexity of the new asset to complex collision. In this way, both assets exist in the scene to handle different collision needs.