This book will act as a single source guide to active 3D sensing as it will detail for each technology the basic principle and mathematical modellingwith the intention to provide a generic unifying framework. Active 3D Sensing will address the different technologies in active sending, explain how to recover 3D data as well as how to process and manipulate the collected data and then detail the main applications of each technology. The book will integrate active 3D sensing explicitly into computer vision and image processing theories and approaches, with the opportunity to connect active vision and passive vision in a unifying framework, with common models and mathematical language, which has not been proposed so far in the current book literature.