I understand planes are merged, but this shouldn't happen if it produces wildly wrong results! See the photo below. In the top one you can see the opening into the hallway has been partly closed off by merging the plane above the hole with the one to the right This should have been represented as 2 rectangular planes, leaving the hallway open. In the bottom row you can see how the open part of the U shaped desk was completely filled in. These desks should have been represented as 4 planes with the open part left open. I've seen similar behavior with L shaped tables being represented as triangular planes. It seems ARKit is being overly aggressive at merging planes, to the point of generating very wrong results. If I use these planes for the placement of objects in an app it would result in things sitting on thin air. I don't expect a perfect representation from planes, but it doesn't seem right to merge them in a way that extends them into large empty spaces.