A Study on the Growth Monitoring Method of Rice Plants by Laser Scanner from Above

摘要

The laser scanner is a useful tool to measure the shape of objects as 3D cloud point data. The laser scanner measurement is used to obtain the shape information of crop plants, although the 3D cloud point data from several locations surrounding the crop plants were required in previous studies. The detection of ground level is also needed to monitor the growth of crop plants. The current monitoring method described above consumes too much time and labor, therefore a new way of monitoring the growth of crop plants without determination of the ground level was examined. In this paper, the 3D cloud point data was acquired by a laser scanner above the rice plants. Firstly, the possibility of monitoring the growth of rice plants using the laser scanner measurement was examined to analyze the relationship between the 3D cloud point data and vegetation coverage of rice plants. The vegetation coverage is a well known parameter indicating the growth of rice plants. In the examination, the laser pulse incident ratio was calculated each time based on the plant height. Then, the relative heights calculated using the laser pulse incident ratios and the vegetation coverage were compared. As a result of this comparison, we found the 3D cloud point data occurring within the upper 80 % of the laser pulse incident ratio depth contains the information about most parts of the crop plants. Finally, the laser pulse incident depths below the plant's crown derived from the 3D cloud point data were calculated and these were compared with the vegetation coverage of rice plants. As a result, the comparison shows that the laser pulse incidence depth is a good parameter to monitor the vegetation coverage of rice plants, and therefore the status of their growth.