Text

theses

Accretion/deletion, where a moving texture appears from (i.e. accretion) or disappears (i.e. deletion) at a boundary, is widely considered as a reliable cue to surface depth ordering, with the accreting or deleting surface interpreted as behind the adjoining surface. However, Froyen, Feldman, and Singh (2013) showed that when accretion- deletion occurs on both sides of a contour, some accreting-deleting regions can also be perceived as in front and as self-occluding due to rotation in 3D. In this study we ask whether geometric figure-ground cues can override the standard “depth from accretion-deletion” interpretation even when accretion-deletion takes place only on one side of a contour. We used two tasks: a relative depth task (front/back), and a motion classification task (translation/rotation). We conducted two experiments, where only one set of alternating regions contained moving texture; the other set was static. In such displays the standard accretion-deletion account would unambiguously assign farther depth to the moving regions. However, when the moving regions were convex or symmetric, they tended to be perceived as figural, and rotating in 3D (with convexity > symmetry). In the second experiment, different motion directions were given to the moving regions (hence weakening motion-based grouping) and this further weakened the traditional accretion-deletion interpretation. Our results show that the standard “depth from accretion-deletion” interpretation is overridden by geometric cues to figure-ground. When this happens, the accreting-deleting surface is perceived as self-occluding due to rotation in 3D. Overall, the results demonstrate a rich interaction between accretion-deletion, figure-ground, and structure-from-motion that is not captured by existing models of depth from motion.

ETD_5268

M.S.

Includes bibliographical references

by Ö. Dağlar Tanrikulu

doi:10.7282/T3FQ9TQ4

ETD graduate

The author owns the copyright to this work.