Potential of low cost close‐range photogrammetry system in soil microtopography quantification

Abstract

AbstractSoil microtopography is a dynamic soil property which affects most soil‐surface and water interaction processes. The importance of soil microtopography has been recognized for a long time, but only limited reports are available in the literature. In this study, the potential of using consumer‐grade cameras and close‐range photogrammetry procedures to quantify soil microtopography at plot‐scale level (≤1 m2) were assessed. Five fabricated gypsum surfaces with different degrees of roughness were used to simulate the soil surface conditions with different soil aggregates. The surfaces' digital elevation model (DEM) was generated using the photogrammetry system (PHM) involving a consumer‐grade camera, and pin‐microrelief meter (PM). The DEM generated using the PHM was assessed for accuracy, roughness indices (RI), depression area percentage (DA%), depression storage capacity (DSC), and micro‐rills delineation in comparison with the PM. The accuracy was evaluated using the root mean square error (RMSE) in the x‐, y‐, and z‐directions. Visual comparison between the 3D‐visions of the DEM showed strong agreement between the DEM generated by the PHM and the PM, and between the PHM and the 2D images for the different gypsum surfaces. The average RMSE in the x‐. y‐, and z‐direction were 2·08, 1·52, and 0·82 mm for the rough surface, and 4·42, 1·65, and 3·22 mm for the smooth surface. The RIs calculated from the two methods were highly correlated. The small discrepancy between the two methods was discussed. The micro‐rills delineation was also similar for the two methods regarding the network density. The grid size did not effect the RI calculation, and has a strong influence on the DA%, DSC, and the delineated micro‐rills orders. Results suggest that a consumer‐grade camera and close‐range photogrammetry have the potential to quantify the soil microtopography. Copyright © 2009 John Wiley & Sons, Ltd.