Efficient 3D terrain mapping based on normal distribution transform grid

Researches about semantic terrain mapping using data acquired from range sensors have been widely studied. And this semantic map can be used for navigation, exploration and path planning. Among the various information `traversability' is important before everything. Because only if traversability information is provided in advance, various high-level robot's tasks are possible. The proposed efficient 3d terrain mapping method use NDT grid. And by using NDT grid's covariance matrix, we define traversability using three different factors `slope', `flatness', `reliability'. Experimental results show by our proposed method traversability can be analyzed efficiently, and accurately.