Essentially it's ray-tracing but in a grid. Bresenham's algorithm let's you do the ray-tracing efficiently.
This is done because a LIDAR/sonar/whatever scanning range sensor returns the angle and range to a reflective object. In most cases, there's an implicit additional piece of information - namely that there's nothing in between the sensor and the object, since the EM radiation was able to get there and back. Bresenham's algorithm is used to tell you the grid cells in which you can assume free space.
This is done because a LIDAR/sonar/whatever scanning range sensor returns the angle and range to a reflective object. In most cases, there's an implicit additional piece of information - namely that there's nothing in between the sensor and the object, since the EM radiation was able to get there and back. Bresenham's algorithm is used to tell you the grid cells in which you can assume free space.