Original sentence: A more theoretically based approach usefull for raytracing would try to choose the position and orientation of the splitting plane in such a way that the probable cost of the resulting tree is minimized.If estimated cost of splitting is lower than the cost of not splitting then the current volume will be split using a splitting plane at the chosen position/orientation.The Surface Area Heuristic (SAH) calculates for every potential split point the following value:.The cost of not splitting at all is.The split position/orientation with the lowest SAH-value is compared to the probable cost of not splitting at all