Interactive sensing in retro-reflective imaging systems may be enabled through auto-alignment of an infrared (IR) illumination region with a floating image region by transmitting IR light, added on or within a display, through the same optical path as the visible floating image light. The IR illumination at the display may be either a flood of light or structured light. In some implementations, stereo vision based imaging techniques may be employed in conjunction with an auto-aligned IR floating image to provide illumination for a stereo imaging system and to provide position sensing for interaction.