{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T17:15:11Z","timestamp":1785863711328,"version":"3.56.0"},"reference-count":42,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2020,1,9]],"date-time":"2020-01-09T00:00:00Z","timestamp":1578528000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000921","name":"European Cooperation in Science and Technology","doi-asserted-by":"publisher","award":["CA16219"],"award-info":[{"award-number":["CA16219"]}],"id":[{"id":"10.13039\/501100000921","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100010022","name":"University of Worcester","doi-asserted-by":"publisher","award":["14005220"],"award-info":[{"award-number":["14005220"]}],"id":[{"id":"10.13039\/100010022","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Image velocimetry has proven to be a promising technique for monitoring river flows using remotely operated platforms such as Unmanned Aerial Systems (UAS). However, the application of various image velocimetry algorithms has not been extensively assessed. Therefore, a sensitivity analysis has been conducted on five different image velocimetry algorithms including Large Scale Particle Image Velocimetry (LSPIV), Large-Scale Particle Tracking Velocimetry (LSPTV), Kanade\u2013Lucas Tomasi Image Velocimetry (KLT-IV or KLT), Optical Tracking Velocimetry (OTV) and Surface Structure Image Velocimetry (SSIV), during low river flow conditions (average surface velocities of 0.12\u20130.14 m s      \u2212 1     , Q60) on the River Kolubara, Central Serbia. A DJI Phantom 4 Pro UAS was used to collect two 30-second videos of the surface flow. Artificial seeding material was distributed homogeneously across the rivers surface, to enhance the conditions for image velocimetry techniques. The sensitivity analysis was performed on comparable parameters between the different algorithms, including the particle identification area parameters (such as Interrogation Area (LSPIV, LSPTV and SSIV), Block Size (KLT-IV) and Trajectory Length (OTV)) and the feature extraction rate. Results highlighted that KLT and SSIV were sensitive to changing the feature extraction rate; however, changing the particle identification area did not affect the surface velocity results significantly. OTV and LSPTV, on the other hand, highlighted that changing the particle identification area presented higher variability in the results, while changing the feature extraction rate did not affect the surface velocity outputs. LSPIV proved to be sensitive to changing both the feature extraction rate and the particle identification area. This analysis has led to the conclusions that for surface velocities of approximately 0.12 m s      \u2212 1      image velocimetry techniques can provide results comparable to traditional techniques such as ADCPs. However, LSPIV, LSPTV and OTV require additional effort for calibration and selecting the appropriate parameters when compared to KLT-IV and SSIV. Despite the varying levels of sensitivity of each algorithm to changing parameters, all configuration image velocimetry algorithms provided results that were within 0.05 m s      \u2212 1      of the ADCP measurements, on average.<\/jats:p>","DOI":"10.3390\/rs12020232","type":"journal-article","created":{"date-parts":[[2020,1,10]],"date-time":"2020-01-10T04:06:51Z","timestamp":1578629211000},"page":"232","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":69,"title":["An Evaluation of Image Velocimetry Techniques under Low Flow Conditions and High Seeding Densities Using Unmanned Aerial Systems"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7428-4793","authenticated-orcid":false,"given":"Sophie","family":"Pearce","sequence":"first","affiliation":[{"name":"School of Science and the Environment, University of Worcester, Worcester WR2 6AJ, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0218-2843","authenticated-orcid":false,"given":"Robert","family":"Ljubi\u010di\u0107","sequence":"additional","affiliation":[{"name":"The Faculty of Civil Engineering, University of Belgrade, Belgrade 11120, Serbia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Salvador","family":"Pe\u00f1a-Haro","sequence":"additional","affiliation":[{"name":"Photrack AG: Flow Measurements, Ankerstrasse 16a, 8004 Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthew","family":"Perks","sequence":"additional","affiliation":[{"name":"School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5176-3492","authenticated-orcid":false,"given":"Flavia","family":"Tauro","sequence":"additional","affiliation":[{"name":"Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, 01100 Viterbo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7242-6559","authenticated-orcid":false,"given":"Alonso","family":"Pizarro","sequence":"additional","affiliation":[{"name":"Department of European and Mediterranean Cultures: Architecture, Environment and Cultural Heritage (DICEM), University of Basilicata, 75100 Matera, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Silvano","family":"Dal Sasso","sequence":"additional","affiliation":[{"name":"Consortium of Italian Universities for Hydrology (CINID), 85100 Potenza, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dariia","family":"Strelnikova","sequence":"additional","affiliation":[{"name":"School of Geoinformation, Carinthia University of Applied Sciences, 9524 Villach, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Salvatore","family":"Grimaldi","sequence":"additional","affiliation":[{"name":"Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, 01100 Viterbo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ian","family":"Maddock","sequence":"additional","affiliation":[{"name":"School of Science and the Environment, University of Worcester, Worcester WR2 6AJ, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5919-6912","authenticated-orcid":false,"given":"Gernot","family":"Paulus","sequence":"additional","affiliation":[{"name":"School of Geoinformation, Carinthia University of Applied Sciences, 9524 Villach, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9679-8851","authenticated-orcid":false,"given":"Jasna","family":"Plav\u0161i\u0107","sequence":"additional","affiliation":[{"name":"The Faculty of Civil Engineering, University of Belgrade, Belgrade 11120, Serbia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0156-7271","authenticated-orcid":false,"given":"Du\u0161an","family":"Prodanovi\u0107","sequence":"additional","affiliation":[{"name":"The Faculty of Civil Engineering, University of Belgrade, Belgrade 11120, Serbia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0225-144X","authenticated-orcid":false,"given":"Salvatore","family":"Manfreda","sequence":"additional","affiliation":[{"name":"Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, 80125 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Process."},{"key":"ref_2","unstructured":"Boiten, W., and Boiten, W. (2008). Hydrometry: IHE Delft Lecture Note Series, CRC Press."},{"key":"ref_3","unstructured":"WMO (2010). Manual on Stream Gauging, Volume II\u2013Computation of Discharge, WMO."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1029\/1999GL006087","article-title":"Measuring stream discharge by non-contact methods: A proof-of-concept experiment","volume":"27","author":"Costa","year":"2000","journal-title":"Geophys. Res. Lett."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.jhydrol.2010.05.049","article-title":"Performance of image-based velocimetry (LSPIV) applied to flash-flood discharge measurements in Mediterranean rivers","volume":"394","author":"Hauet","year":"2010","journal-title":"J. Hydrol."},{"key":"ref_6","unstructured":"Smith, J., B\u00e9rub\u00e9, F., and Bergeron, N. (2005, January 14\u201316). A field application of particle image velocimetry (PIV) for the measurement of surface flow velocities in aquatic habitat studies. Proceedings of the 26th Canadian Symposium on Remote Sensing, Wolfville, NS, Canada."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1016\/j.advwatres.2014.04.004","article-title":"Capabilities of large-scale particle image velocimetry to characterize shallow free-surface flows","volume":"70","author":"Muste","year":"2014","journal-title":"Adv. Water Resour."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"937","DOI":"10.1061\/(ASCE)0733-9429(2004)130:9(937)","article-title":"Large scale particle image velocimetry for low velocity and shallow water flows","volume":"130","author":"Meselhe","year":"2004","journal-title":"J. Hydraul. Eng."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1080\/00221689809498626","article-title":"Large-scale particle image velocimetry for flow analysis in hydraulic engineering applications","volume":"36","author":"Fujita","year":"1998","journal-title":"J. Hydraul. Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1114","DOI":"10.1002\/hyp.10698","article-title":"Assessment of drone-based surface flow observations","volume":"30","author":"Tauro","year":"2015","journal-title":"Hydrol. Process."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1146\/annurev.fl.23.010191.001401","article-title":"Particle-imaging techniques for experimental fluid mechanics","volume":"23","author":"Adrian","year":"1991","journal-title":"Annu. Rev. Fluid Mech."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"7977","DOI":"10.1002\/2015WR017783","article-title":"Resolving two-dimensional flow structure in rivers using large-scale particle image velocimetry: An example from a stream confluence","volume":"51","author":"Lewis","year":"2015","journal-title":"Water Resour. Res."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Fujita, I., Notoya, Y., and Furuta, T. (2018, January 5\u20138). Measurement of Inundating Flow from a Broken Enbankment by Using Video Images Shoot from a Media Helicopter. Proceedings of the Ninth International Conference on Fluvial Hydraulics, Villeurbanne, France.","DOI":"10.1051\/e3sconf\/20184006001"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Le Coz, J., Jodeau, M., Hauet, A., Marchand, B., and Le Boursicaud, R. (2014, January 3\u20135). Image-based velocity and discharge measurements in field and laboratory river engineering studies using the free Fudaa-LSPIV software. Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW, Lausanne, Switzerland.","DOI":"10.1201\/b17133-262"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/j.jhydrol.2018.03.008","article-title":"Integrating unmanned aerial systems and LSPIV for rapid, cost-effective stream gauging","volume":"560","author":"Lewis","year":"2018","journal-title":"J. Hydrol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"460","DOI":"10.1007\/s10661-018-6848-3","article-title":"Exploring the optimal experimental setup for surface flow velocity measurements using PTV","volume":"190","author":"Pizarro","year":"2018","journal-title":"Environ. Monit. Assess."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"241","DOI":"10.5194\/gi-5-241-2016","article-title":"A novel permanent gauge-cam station for surface-flow observations on the Tiber River","volume":"5","author":"Tauro","year":"2016","journal-title":"Geosci. Instrum. Methods Data Syst."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"791","DOI":"10.1016\/j.jhydrol.2018.09.001","article-title":"Urban overland runoff velocity measurement with consumer-grade surveillance cameras and surface structure image velocimetry","volume":"565","author":"Scheidegger","year":"2018","journal-title":"J. Hydrol."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Tauro, F., Tosi, F., Mattoccia, S., Toth, E., Piscopia, R., and Grimaldi, S. (2018). Optical tracking velocimetry (OTV): Leveraging optical flow and trajectory-based filtering for surface streamflow observations. Remote Sens., 10.","DOI":"10.3390\/rs10122010"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"4005","DOI":"10.5194\/hess-20-4005-2016","article-title":"Technical Note: Advances in flash flood monitoring using unmanned aerial vehicles (UAVs)","volume":"20","author":"Perks","year":"2016","journal-title":"Hydrol. Earth Syst. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1016\/j.jher.2010.12.004","article-title":"Measurement of the flood discharge of a small-sized river using an existing digital video recording system","volume":"5","author":"Tsubaki","year":"2011","journal-title":"J. Hydro-Environ. Res."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Kim, Y., Muste, M., Hauet, A., Krajewski, W.F., Kruger, A., and Bradley, A. (2008). Stream discharge using mobile large-scale particle image velocimetry: A proof of concept. Water Resour. Res., 44.","DOI":"10.1029\/2006WR005441"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Eltner, A., Sardemann, H., and Grundmann, J. (2019). Flow velocity and discharge measurement in rivers using terrestrial and UAV imagery. Hydrol. Earth Syst. Sci. Discuss., 2019.","DOI":"10.5194\/hess-2019-289"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Thielicke, W., and Stamhuis, E. (2014). PIVlab\u2014Towards user-friendly, affordable and accurate digital particle image velocimetry in MATLAB. J. Open Res. Softw., 2.","DOI":"10.5334\/jors.bl"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"199","DOI":"10.4081\/jae.2018.836","article-title":"Optical sensing for stream flow observations: A review","volume":"49","author":"Tauro","year":"2018","journal-title":"J. Agric. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"7470","DOI":"10.1002\/2014WR015952","article-title":"Orienting the camera and firing lasers to enhance large scale particle image velocimetry for streamflow monitoring","volume":"50","author":"Tauro","year":"2014","journal-title":"Water Resour. Res."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Muste, M., Fujita, I., and Hauet, A. (2008). Large-scale particle image velocimetry for measurements in riverine environments. Water Resour. Res., 44.","DOI":"10.1029\/2008WR006950"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1016\/j.proeng.2015.11.031","article-title":"Application of large scale particle image velocimetry (LSPIV) to identify flow pattern in a channel","volume":"125","author":"Sutarto","year":"2015","journal-title":"Procedia Eng."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1016\/S0955-5986(02)00059-6","article-title":"Large scale PIV-measurements at the surface of shallow water flows","volume":"13","author":"Weitbrecht","year":"2002","journal-title":"Flow Meas. Instrum."},{"key":"ref_30","unstructured":"Sontek (2015). River Survey or S5\/M9\u2014Discharge, Bathymetry and Current Profiling (brochure), Sontek."},{"key":"ref_31","first-page":"4218","article-title":"Evaluation of acoustic Doppler current profiler measurements of river discharge","volume":"95","author":"Morlock","year":"1996","journal-title":"Water-Resour. Investig. Rep."},{"key":"ref_32","unstructured":"Mueller, D.S., Wagner, C.R., Rehmel, M.S., Oberg, K.A., and Rainville, F. (2009). Measuring Discharge with Acoustic Doppler Current Profilers from a Moving Boat."},{"key":"ref_33","unstructured":"Blachard, S.F. (2005). Office of Surface Water Technical Memorandum 2005.05: Guidance on the Use of RD Instruments StreamPro Acoustic Doppler Profiler, Technical Report."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Wolf, P.R., and Ghilani, C. (1995). Survey Measurement Adjustments by Least Squares. The Surveying Handbook, Springer.","DOI":"10.1007\/978-1-4615-2067-2_16"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"10374","DOI":"10.1002\/2017WR020848","article-title":"Streamflow observations from cameras: Large-scale particle image velocimetry or particle tracking velocimetry?","volume":"53","author":"Tauro","year":"2017","journal-title":"Water Resour. Res."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/j.margeo.2004.07.001","article-title":"Estimating suspended solids concentrations from backscatter intensity measured by acoustic Doppler current profiler in San Francisco Bay, California","volume":"211","author":"Gartner","year":"2004","journal-title":"Mar. Geol."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Manfreda, S., McCabe, M.F., Miller, P.E., Lucas, R., Pajuelo Madrigal, V., Mallinis, G., Ben Dor, E., Helman, D., Estes, L., and Ciraolo, G. (2018). On the use of unmanned aerial systems for environmental monitoring. Remote Sens., 10.","DOI":"10.20944\/preprints201803.0097.v1"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1002\/esp.3613","article-title":"Quantifying submerged fluvial topography using hyperspatial resolution UAS imagery and structure from motion photogrammetry","volume":"40","author":"Woodget","year":"2015","journal-title":"Earth Surf. Process. Landf."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"857","DOI":"10.1002\/esp.4285","article-title":"From manned to unmanned aircraft: Adapting airborne particle size mapping methodologies to the characteristics of sUAS and SfM","volume":"43","author":"Woodget","year":"2018","journal-title":"Earth Surf. Process. Landf."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"503","DOI":"10.1002\/esp.4086","article-title":"Application of Structure-from-Motion photogrammetry to river restoration","volume":"42","author":"Marteau","year":"2017","journal-title":"Earth Surf. Process. Landf."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3223","DOI":"10.1007\/s00024-018-1874-1","article-title":"Detection and mapping of the geomorphic effects of flooding using UAV photogrammetry","volume":"175","author":"Langhammer","year":"2018","journal-title":"Pure Appl. Geophys."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"532","DOI":"10.1080\/00221686.2015.1054322","article-title":"A low-cost airborne velocimetry system: Proof of concept","volume":"53","author":"Detert","year":"2015","journal-title":"J. Hydraul. Res."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/2\/232\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T13:19:22Z","timestamp":1760361562000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/2\/232"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,1,9]]},"references-count":42,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2020,1]]}},"alternative-id":["rs12020232"],"URL":"https:\/\/doi.org\/10.3390\/rs12020232","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,1,9]]}}}