Abstract: In order to solve the problems of large calibration error and model reconstruction failure in the

operation of traditional coaling instrument，an improved calibration algorithm based on direct linear transformation model and an improved 3D reconstruction algorithm based on time-of-flight method were proposed. The coaling was realized by a fixed depth sensor and a camera. At the same time，in view of the problems such as the lack of visualization of the coaling instrument and large volume measurement error，the virtual scene design based on Unity3D and the point cloud segmentation method based on color and normal vector were proposed to realize the three-dimensional visualization of the coal field and calculate the model volume.The experimental results show that the improved algorithm has high measuring accuracy，fast scanning speed and strong stability of the equipment，so it has high application value.

      Key words: coaling instrument；3D reconstruction；optimization of bilateral filtering denoising algorithm；

point cloud segmentation；volume measurement