2018 Volume 24 Pages 7-12
To estimate particle size of sand from luminance distribution of sand images, laboratory experiments were conducted. In the experiments, we used four kinds of single particle which was under about 10 mm diameter, which could not recognize contour of sand from sand images, and took pictures in various lightning conditions and display resolutions. The results of the experiments were that the smaller particle size of sand was, the thinner the peak of luminance distribution was, and the larger particle size of sand was, the flatter the peak of luminance distribution was. Based on the above results, we proposed an equation to estimate particle size of sand from the coefficient of variation, 90th percentile, and standard deviation of the luminance distribution. The equation can be adopted to estimate approximate particle size of sand using sand images taken by UAV(Unmanned Aerial Vehicle). However, to estimate particle size of sand more accurately, we need to consider the factor of illumination angle and color tone of sand.
