SLAM (Simultaneous Localization And Mapping) is the way to locate a device indoor. The ability to build a map and simultaneously localize within that map is essential in all robotic applications. The input sensor for SLAM is traditionally a LIDAR. Visual SLAM (VSLAM) uses a mono or stereo camera as input to localize, so a low cost sensor. JACK SLAM is a VSLAM. This technology, much more efficient than LIDAR in many cases, is old but has never been able to have a practical use because of the important CPU resources required. Today, both powerful and inexpensive hardware and the optimizations made by ip sum tek allow the use of VSLAM in real time on low cost computers. The principle to locate is like the one used by humans: Detecting the natural features seen by the camera (a difference in color, an angle, a shape, …). Have a look to the videos of this site to understand the principle.