1: Glossary: probability grid map
After the map is rasterized maps, and maps each pixel value is represented by a probability.
p = 1, represents occupied;
p = 0.5, indicates an unknown map initialization time, each grid may be initialized to 0.5;
p = 0.0, represents a free, i.e. no obstacle is determined.
2: How to update the probability of each grid
Use Odds (odd) to update the probability values of the grid. If the laser is hit (hit), the probability value will increase; If penetration laser (miss), the probability value is decreased.
Note: Each time you update the grid probability, only update the grid current of the laser to see.
3: Update Official
Note: 
represents the probability that the updated value, 
expressed 
that the determination of probability of the reverse process.