Optical and portable equipment for characterizing soil roughness

Abstract

Knowledge of surface roughness with the consequent presence of crust in the soil is important information for the rational management of environmental resources. Soil surface roughness can be determined by contact and noncontact methods. Contact methods have lower values and precision than noncontact methods. Therefore, the objective of this study was to develop low-cost, portable and robust optical equipment to characterize the roughness and presence of crust in the soil through an illumination system with a line laser and monocular vision. The mean roughness was calculated by the difference in height between a point and its neighbours and the presence of crust was determined by a semivariogram. The developed equipment was used in different experimental areas: an eroded area and a compost barn. For the validation of the results, the surface roughness of the same areas analysed by the equipment was also analysed by existing techniques: for the area with erosion, a noncontact technique, i.e., structure from motion (SfM), and for the compost barn, a contact technique, i.e., a pin meter. From the results, it was found that the optical equipment developed to characterize the soil surface roughness and the presence of crust in the soil proved to be valid and provided reliable results.