Yamane Ryo

Study of rice plant height estimation by LiDAR mounted on UAV

Takahashi@Kazuyoshi

Monitoring rice growth is very important for stable production of high quality rice. In the customary measurement, an operator manually measures the plant height, the number of stems, and the leaf color of each rice plant. However, it is difficult for this work method to cover a wide area of the field. In order to solve this problem, research using remote sensing technology has been conducted. In a previous study, Phan et al. proposed a method for estimating rice plant height using the thickness of rice canopy (rD) measured by LiDAR. In the case of applying this method to UAV-LiDAR measurement, it was found that it is necessary to consider the change of the laser footprint diameter due to the increase in measurement altitude. In this study, in order to apply the method to a wider area of the field, I measured with a UAV system (DJI M600j equipped with LiDAR for automotive (Velodyne VLP-16). The measurement altitude, which is about the same as the laser footprint diameter in previous studies, was 10m. As a result, it was found that the rice plant height estimation method can be applied at this measurement altitude. In addition, measurements were taken for a longer period than in previous studies. As a result, the influence on the estimation error of the rice plant height was confirmed. It was found that this method should be applied until the time when rice ears emerge. In addition, measurements were taken at different altitudes (10m, 20m, 30m) on the same course. As a result, it was suggested that there is a possibility that rD decreases as the laser footprint diameter increases. In addition, it was suggested that this UAV-LiDAR measurement system could be used for rice plant height estimation even at a measurement altitude of 20m.