We report 2 exps on the 3D interpolation of surfaces without visible edges. Observers classified pairs of planar patches specified by random dot disparities and visible through aligned vs misaligned apertures (). Surfaces appeared in parallel or converging planes with vertical (in Exp. 1) or horizontal (in Exp. 2) tilt and variable slant. We found enhanced sensitivity and speed for 3D relatable vs. nonrelatable patches. Performance was worse for patches with horizontal tilt. We found nearly identical advantages of 3D relatability on performance, suggesting an isotropic unit formation process. Inducing slant constrains surface interpolation in the absence of explicit edge information: 3D contour and surface interpolation processes share common constraints as formalized by 3D relatability.
