A virtual reference plane for extending the Moiré method to large experimental devices

Abstract

Many tools have been developed to measure the topography of geomorphological systems accurately. Because field investigations are limited by time and space, laboratory experiments are commonly used. The Moiré method has previously been used on a small-scale braided river to observe how channels evolve. Despite its easy implementation, the classical method requires a measurement apparatus fixed in position and therefore a small experimental set-up. In this paper, we present an improvement of the Moiré technique with the creation of a virtual reference plane allowing to measure topography at a larger scale. The method is presented and is used to survey the topography of a braided river experiment. The error induced by the method was evaluated around 0 mm with a standard deviation of 0.10 mm, and the validation process highlighted a mean error of −0.26 mm. It was considered negligible compared to the scale of morphological changes, which were approximately 3 mm high.