Target angle submarine observer estimating target angle pictures himself on the target ship looking back at the submarine. Relative bearing of the submarine is the clockwise angle in degrees from the heading of the target ship to a straight line drawn from the target ship to the submarine. When target angle is 0° (or 360° ) the target ship is coming directly toward the submarine. Target angles between 0° and 90° indicate the target ship is moving toward and to the right of the submarine. Target angles between 90° and 180° indicate the target ship is moving to the right and away
Perceived visual angle Ono & Mapp (2006) noted, it unfortunately has been ignored in many current theories of size perception, and size illusions. The object's other perceived endpoint, A′, has a perceived direction "d′";, about which the observer might say "it appears toward a higher elevation than point B′." The difference between the two perceived directions () is the perceived visual angle "θ′", also called the perceived angular size or apparent angular size. It is not easy to quantify "θ′". For instance, a well-trained observer might say that point A′ "looks about 25 degrees higher" than B′, but most cannot reliably say how