Abstract
This paper describes a spatial measurement technique to measure the free surface of natural fluid flows in laboratory applications. This effective solution is based on “Structure-from- Motion/Multi-view Stereo” (SfM-MVS) photogrammetry and is capable of reconstructing water surface morphology, both at an instant and with a high spatial resolution. The efficiency and accuracy of the method is dependent upon the acquisition of high quality imagery (i.e. sharply focussed, no motion blur) with appropriate multi-frame camera coverage and configuration, and data processing must utilise appropriate camera calibration data. The potential of the technique for developing hydraulic understanding is demonstrated using two contrasting approaches. First, the water surface behind a living vegetation element is analysed along a single transect. Second, the full three-dimensional characteristics of the captured water surfaces are examined using statistical methods which demonstrate surface dissimilarity between vegetated and non-vegetated cases. The technique is transferable to real-world field sites.
Highlights
The need for accurate water depth readings has always been a basic requirement in river engineering practice
Prior to the analysis described below, points of the free surface lying outside our region of interest were removed and dubious point elevations were filtered using a semiautomatic local variance based filter inspired in Lane et al [23]
Two distinct analyses have demonstrated how a dense numerical description of high resolution surface morphology captured at an instant, can answer fundamental questions linked to the nature of the free surface
Summary
The need for accurate water depth readings has always been a basic requirement in river engineering practice. A wide range of approaches aiming to gauge water surface elevations in-situ or in the laboratory have been applied traditionally, ranging from rudimentary techniques involving graduated cables or rods, to more sophisticated methods such as ground penetrating radar or ultrasonic sounders [3]. Researchers working on fluvial hydraulics have extended these measurements, notably in terms of potential applications and spatial description. Common practice in fluvial hydraulics research is still typically characterised by a sparse water elevation or topography (depending whether datum coincides or not with the bed) spatial resolution The work described in this paper provides water surface descriptions at a very high spatial resolution and at an instant through the application of Structure-from-Motion/ Multi-view Stereo (SfM-MVS) photogrammetry
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
