just wondering if this is possible to do is there a way to stream levels only in the direction the player is looking. like if im looking at one building the buildings behind me will unload and if i turn around the buildings will load and the ones behind will unload . no iodea if im making this clear or not but thats the jist of it. just wondering if this is somthign that can be done with say ray tracing ?
If you do manual level streaming (There are BP nodes that do it) you are free to implement any streaming logic you want.
You could do traces at 180 degrees to unstream objects, and traces at 90 degrees to stream them in as your turn. You would want a volume in areas that you want streamed so you trace for the volume and then stream the level that is basically the same size. There are other methods you could use as well which will depend on your implementation and other game specific mechanics.
I wonder though if the unloading and loading of all these assets would be more of a drag than having them constantly loaded in the world. Could be worth a try if only to see how it works on your performance, though I am sure other forum members already have a good idea as to the answer.
worth a try just one of my buildings is over 17k objects and is a performance eater even converted to a bp but i figured if i stream them in it will take a load off if some of them are unloaded when your not looking at them. thanks for the info
Yeah check it out.
I would say though that a lot of game design is hiding the illusion that you are in a simulated space. To maintain the illusion designers use all kinds of tricks, such as you could always keep the shell of the building loaded but stream out the interior, you could make the entire thing into a single mesh, you could orient streets, foliage, and other obstacles so that they obscure the fact that the building is streamed out even if you are looking in that direction, etc.
I guess you push the performance as far as it will go and then you start using whatever tricks and shortcuts you can devise. 
just to update streaming things in with a ton of objects in it is a bad idea if your doing multiples in a small area causes fps drop big time. but using the culling volumes work pretty well in this aspect.