Development of a non‐intrusive and efficient flow monitoring technique: The space‐time image velocimetry (STIV)

Abstract

A novel image analysis technique for measuring river surface flow is proposed. When we assume that the brightness distribution of river surface image is convected with the surface velocity, a space-time image for a searching line set parallel to the main flow would indicate velocity information as its image orientation. The new technique, the space-time image velocimetry (STIV), is capable to measure the orientation angle of the pattern using the eigenvalue analysis of the local space-time image. The performance of STIV is compared with the other image analysis technique, the large-scale particle image velocimetry (LSPIV), previously proposed by the authors and it is shown that STIV is an alternative image analysis method for measuring streamwise velocity distributions efficiently.

Discharge Measurements of Snowmelt Flood by Space-Time Image Velocimetry during the Night Using Far-Infrared Camera

“…Alternatively, STI containing a float trajectory, such as indicated in Figure 12a, can be used for STIV measurement when an FIR camera is not available. The gradient of the pattern can be obtained either manually or automatically with the aid of an STIV algorithm [17].…”

“…The idea behind the use of video images is that surface flow features composed of surface ripples or floating objects are assumed to be advected with the surface velocity as long as the wind effect is negligible. Among the image-based techniques, such as a large-scale image velocimetry (LSPIV) [13][14][15] or the space-time image velocimetry (STIV) [16][17][18][19][20], STIV seems to be more robust under deteriorated image condition and utilized in the present research. The non-intrusive methods are very useful and effective as they can measure the flow velocity information safely from a remote place.…”

Estimación del caudal a partir de la evolución del nivel del agua en un estuario con onda de marea estacionaria

“…Más recientemente, mediciones continuas de la velocidad superficial a partir de métodos de no contacto mostraron ser útiles para estimar la descarga [25][26][27][28][29][30][31][32][33][34][35][36][37]. El desafío consiste en relacionar la velocidad medida en superficie con el flujo subsuperficial.…”

Spatial Measurements of Snowmelt Flood by Image Analysis With Multiple-Angle Images and Radio-Controlled Adcp

“…In STIV, streamwise velocity spatially and temporally averaged along a search line set in the direction of the main flow can be measured first by generating a space-time image (STI) for each search line 16) . STIs are constructed by piling up the image intensity distribution (IID) along a search line taking IID as the horizontal axis and the number of image frame, i.e., time, in the vertical axis.…”

“…Therefore, in this research, we took measurements of a snowmelt flood of the Uono River, a tributary of the Shinano River, concurrently with a radio-controlled boat-mounted ADCP and space-time image velocimetry (STIV) 16) in order to examine the measurement accuracy.…”