Interaction in virtual and augmented reality is inherently spatial and embodied. Immersive user interfaces leverage the rich sensory resources of the human body and enable compelling interactive experiences using physical motion, gestures, and tangible objects. However, these emerging interaction paradigms also introduce design and implementation challenges for usability, ease of use, and physical fatigue. The Illusioneering Lab researches novel spatial techniques. develops enabling technologies, and investigates how embodied interaction be applied in immersive applications for health, rehabilitation, training, and entertainment.