I was going to say that you should probably fire random rays from the camera position but after a quick search I found this: Perform Frustum Check
(Note this uses player’s camera)
The other thing I can think of is just check the horizontal and vertical angle to the camera’s forward vector. In this case you have to figure out how precise you want to be.
- You can do it with the actor’s origin but ti will produce false negatives.
- You can try it with the end points of the Bounding Box which can get false positives.