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Craig W Sauer, George J Andersen, Asad Saidpour; Linearly changing bearing and collision detection of objects traveling on curved 3D trajectories. Journal of Vision 2003;3(9):793. doi: 10.1167/3.9.793.
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© ARVO (1962-2015); The Authors (2016-present)
In previous work on collision detection (Andersen & Kim, 2001) involving objects following linear trajectories, it was found that the optical information specifying a collision was constant bearing and image expansion. This is not true for objects following nonlinear trajectories. In the present study, we used objects following trajectories of constant curvature, which project linearly changing bearings when they are on collision courses. Displays simulated a stationary observer with a spherical object approaching on a circular path at eyeheight from the horizon. We varied path curvature, the starting position of the collision object, and display duration, and maintained time-to-contact and object speed. Observers were asked to determine whether the object was on a path that would intersect the observer's position, resulting in a collision. Observers were more accurate when the slope of the linear change in bearing was closer to zero. Collisions resulting in linear but rapidly changing bearing could also be discriminated, but observers were less accurate in these cases. These results indicate that the slope of the change in bearing is quite important for deciding if an object is on a collision path, despite the fact that the slope has no geometric relevance in this case.
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