GPS only works outdoors.  For indoor navigation, a general-purpose, accurate and low-cost positioning system is still needed.  AltVision has invented a new materials approach for indoor positioning.  The ceilings, walls, and floors can be coated with invisible nano material that is passive and illuminated by ambient light.  The nano material is detected by off-the-shelf near-infrared (NIR) cameras that can be integrated into robots, smart-phones, head-mount displays, smart-glasses, and other electronic systems.  The nano material serves as "indoor satellites" that, through trilateration, can be used to determine the sensors' positions with centimeter-level accuracy.  This positional tracking technology can be used for different applications, including robot and drone position tracking, way-finding in stores, virtual reality (VR), and augmented reality (AR).