The visual system uses multiple cues to estimate properties of interest. Since the errors in the estimates from different cues for the same property are generally different, a weighted average of the cues provides a better overall estimate. The most precise estimate is found when each cue's weight is proportional to its reliability. We here show that the weights given to cues for surface slant can differ between two transparent surfaces that are at the same location at the same time. Thus the weights must be assigned separately for each structure, rather than for each location.