EFFECT OF PHOTOGRAPHIC CONDITIONS ON IMAGE MESUREMENT OF GRAIN SIZE DISTRIBUTION USING AUTOCORRELATION FUNCTION OF VIRTUAL SEDIMENT IMAGES

Abstract

 Grain size distribution is a fundamental information for sandy beach management and is essential for predicting the future sandy beach environment with climate change. However, it is difficult in terms of time and cost to make high-frequency monitoring over the entire beach. In this study, we aimed to develop a simple method to estimate grain size distribution from images taken by a smartphone, which is widely used by the general public, and examined the applicability of the calibration method using the virtual sediment images and effect of photographic conditions. A comparison between the conventional median grain size and that of defined by area percentages was conducted.