Method for implementing a lidar device with descriptors employing distance evaluation

A method for using a light detection and ranging (LIDAR) device in a motor vehicle, the method comprising:

• emitting incident light rays from the motor vehicle toward its external environment;
• receiving in return reflected light rays on a photodetector of the motor vehicle;
• associating a value representing a quantity relating to the reflected light ray with each cell of the photodetector that receives a reflected light ray;
• a step of determining a first descriptor comprising a first set of environment signatures for a selection of cells of the photodetector, with this first descriptor corresponding to a first sequence for receiving reflected light rays;
• a step of determining a second descriptor comprising a second set of environment signatures for a selection of cells of the photodetector, with this second descriptor corresponding to a second sequence for receiving reflected light rays;
• a step of identifying the environment signatures that are matching in the first descriptor and the second descriptor;
• an environment signature of a particular cell of the photodetector being defined as a set of distance indicators, each associated with one cell of a predetermined pattern of environment cells of said particular cell, each of said distance indicators being adapted to take a value representative of one of the following four states:
• the cell concerned is associated with a distance away which is outside a first predetermined range of distances relative to the distance away that is associated with said particular cell;
• the cell concerned is associated with a distance away which is located in a lower segment of said first predetermined range of distances;
• the cell concerned is associated with a distance away which is located in an upper segment of said first predetermined range of distances;
• the cell concerned is associated with a distance away which is substantially equal to the distance away that is associated with said particular cell, to within a predetermined factor.