Alpha transition is very greeat. just check Oblivion or Skyrim !
You are in place A and have lot of details and characters around you , Place B is some meters far. Now if you are not distracted from all details in place A, if you stop playing and just watch, you look at the place B, you'll see nothing only basic structures , no characters , no details 3D assets.
Now you approach slighlty step by step and you'll see as you approch to place B objects fading with alpha transition very very smoosly, sometimes with no LOD ! Same things they were characters you didn't see that appears with alpah transition.
It works just great when you are playing, caus you are concentrated on other things and the alpha transition makes that you don't notice the appearence. Compared to old clipping engines of old days , here you won't notice anything