Spatial augmented reality (SAR) technology allows one to change the appearance of objects by projecting directly onto their surface without the requirement of wearing glasses, and therefore can be used in many practical applications. In this article, we present a human–subject study, which investigates the research question whether it is possible to use SAR to change one's perception of depth and spatial relationships among objects and humans in a real-world environment. Such projected illusions could open up new possibilities, for example, supporting people who suffer from poor depth perception by compensating distance and size misperceptions. We present three monoscopic projection-based techniques that we adapted from visual arts: (i) color temperature, (ii) luminance contrast, and (iii) blur, and show that each of them can significantly change depth perception, even in a real-world environment when displayed with other distance cues. We discuss practical implications and individual differences in the perception of depth between observers, and we outline future directions to influence and improve human depth perception in the real world.