When the texture on a ground surface is discontinuous, its more distant part appears as slanted towards the observer (Wu, Ooi & He, 2004). If exists, for a slanted surface such an effect will reduce the perceived slant of the further parts.
The present study examines the effect of motion and distance on perceived slant of a planar surface textured either with one or with two textures and divided by a horizontal gap. The textures had amplitude spectrum with falloff of 1/f or 1/f1.5. The observer had to adjust the slant of the upper or of the lower part so that they appeared coplanar.
Results. For the plane translated under perspective projection, there were less errors in the adjusted slant when both planar patches had the same texture irrespective of its amplitude spectrum. For rotating planes in orthographic projection, the performance was best for lower (and closer) planar patch when both parts were covered with 1/f noise texture. Largest errors were observed when the patches were covered with 1/f1.5 texture due either to the lower density of the motion signals or to the discrepancy between the motion information and the perceived depth of this texture.
The results suggest that motion information can improve to a limited extent the integration of depth information over a gap and its effect depends on the variability of the texture anisotropy during the motion.