For drawing a map of a place. (Simultaneous localization and mapping). Monocular meaning single camera.
https://vision.in.tum.de/research/vslam/lsdslam
https://ubilang.wordpress.com/2016/05/07/orb-slam-vs-lsd-slam/
and point clouds
http://pointclouds.org/blog/tocs/alexandrov/index.php
https://github.com/PointCloudLibrary/pcl