{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T04:29:31Z","timestamp":1772252971760,"version":"3.50.1"},"reference-count":58,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2018,6,1]],"date-time":"2018-06-01T00:00:00Z","timestamp":1527811200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"SPIRIT BAPPENAS-World Bank","award":["IBRD No. 8010-IND"],"award-info":[{"award-number":["IBRD No. 8010-IND"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Unmanned aerial vehicles (UAV) provide an unprecedented capacity to monitor the development and dynamics of tree growth and structure through time. It is generally thought that the pruning of tree crops encourages new growth, has a positive effect on fruiting, makes fruit-picking easier, and may increase yield, as it increases light interception and tree crown surface area. To establish the response of pruning in an orchard of lychee trees, an assessment of changes in tree structure, i.e., tree crown perimeter, width, height, area and Plant Projective Cover (PPC), was undertaken using multi-spectral UAV imagery collected before and after a pruning event. While tree crown perimeter, width and area could be derived directly from the delineated tree crowns, height was estimated from a produced canopy height model and PPC was most accurately predicted based on the NIR band. Pre- and post-pruning results showed significant differences in all measured tree structural parameters, including an average decrease in tree crown perimeter of 1.94 m, tree crown width of 0.57 m, tree crown height of 0.62 m, tree crown area of 3.5 m2, and PPC of 14.8%. In order to provide guidance on data collection protocols for orchard management, the impact of flying height variations was also examined, offering some insight into the influence of scale and the scalability of this UAV-based approach for larger orchards. The different flying heights (i.e., 30, 50 and 70 m) produced similar measurements of tree crown width and PPC, while tree crown perimeter, area and height measurements decreased with increasing flying height. Overall, these results illustrate that routine collection of multi-spectral UAV imagery can provide a means of assessing pruning effects on changes in tree structure in commercial orchards, and highlight the importance of collecting imagery with consistent flight configurations, as varying flying heights may cause changes to tree structural measurements.<\/jats:p>","DOI":"10.3390\/rs10060854","type":"journal-article","created":{"date-parts":[[2018,6,1]],"date-time":"2018-06-01T03:02:50Z","timestamp":1527822170000},"page":"854","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":57,"title":["Using Multi-Spectral UAV Imagery to Extract Tree Crop Structural Properties and Assess Pruning Effects"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1889-9336","authenticated-orcid":false,"given":"Kasper","family":"Johansen","sequence":"first","affiliation":[{"name":"Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Al Jazri Building West, Thuwal 23955-6900, Saudi Arabia"},{"name":"Remote Sensing Research Centre, School of Earth and Environmental Sciences, The University of Queensland, St Lucia, QLD 4072, Australia"}]},{"given":"Tri","family":"Raharjo","sequence":"additional","affiliation":[{"name":"Remote Sensing Research Centre, School of Earth and Environmental Sciences, The University of Queensland, St Lucia, QLD 4072, Australia"},{"name":"Ministry of Agrarian and Spatial Planning, National Land Agency, Jalan H. Agus Salim 58, Jakarta Pusat 10350, Indonesia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1279-5272","authenticated-orcid":false,"given":"Matthew F.","family":"McCabe","sequence":"additional","affiliation":[{"name":"Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Al Jazri Building West, Thuwal 23955-6900, Saudi Arabia"}]}],"member":"1968","published-online":{"date-parts":[[2018,6,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"949","DOI":"10.3390\/rs5020949","article-title":"Advances in remote sensing of agriculture: Context description, existing operational monitoring systems and major information needs","volume":"5","author":"Atzberger","year":"2013","journal-title":"Remote Sens."},{"key":"ref_2","first-page":"1","article-title":"Detecting and monitoring plant nutrient stress using remote sensing approaches: A review","volume":"16","author":"Me","year":"2017","journal-title":"Asian J. Plant Sci."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Ikinci, A. (2014). Influence of pre- and postharvest summer pruning on the growth, yield, fruit quality, and carbohydrate content of early season peach cultivars. Sci. World J.","DOI":"10.1155\/2014\/104865"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1186\/s13007-017-0205-3","article-title":"Quantifying pruning impacts on olive tree architecture and annual canopy growth by using UAV based 3D modelling","volume":"13","author":"Serrano","year":"2017","journal-title":"Plant Methods"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"124","DOI":"10.1016\/j.compag.2011.09.007","article-title":"A review of methods and applications of the geometric characterization of tree crops in agricultural activities","volume":"81","author":"Rosell","year":"2012","journal-title":"Comput. Electron. Agric."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1111\/j.1469-8137.2007.02088.x","article-title":"Simple equations to estimate light interception by isolated trees from canopy structure features: Assessment with three-dimensional digitized apple trees","volume":"175","author":"Sinoquet","year":"2007","journal-title":"New Phytol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/j.scienta.2014.02.010","article-title":"Structure management and productivity of hedgerow olive orchards: A review","volume":"169","author":"Connor","year":"2014","journal-title":"Sci. Hortic."},{"key":"ref_8","unstructured":"Papademetriou, M.K., and Dent, F.J. (2002). Lychee production in Australia. Lychee Production in the Asia-Pacific Region, Food and Agriculture Organization of the United Nations, Regional Office for Asia and the Pacific. [1st ed.]. RAP Publication 2002\/04."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"238","DOI":"10.21273\/HORTSCI.24.2.238","article-title":"Postharvest summer pruning of \u201cFirebrite\u201d nectarine trees","volume":"24","author":"Day","year":"1989","journal-title":"HortScience"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"975","DOI":"10.21273\/JASHS.107.6.975","article-title":"Regrowth, flowering and fruit quality of \u201cdelicious\u201d apple trees as influenced by pruning treatments","volume":"107","author":"Miller","year":"1982","journal-title":"J. Am. Soc. Hortic. Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"83","DOI":"10.17660\/ActaHortic.2012.965.8","article-title":"Improving canopy contact olive harvester efficiency with mechanical pruning","volume":"965","author":"Ferguson","year":"2012","journal-title":"Acta Hortic."},{"key":"ref_12","unstructured":"Campbell, T.P., and Diczbalis, Y. (2001). Pruning to Meet Your Lychee Goals: A Report for the Rural Industries Research and Development Corporation, Rural Industries Research and Development Corporation."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2365","DOI":"10.1080\/0143116031000139863","article-title":"Change detection techniques","volume":"25","author":"Lu","year":"2004","journal-title":"Int. J. Remote Sens."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1007\/s11119-012-9274-5","article-title":"The application of small Unmanned Aerial Systems for precision agriculture: A review","volume":"13","author":"Zhang","year":"2012","journal-title":"Precis. Agric."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2053","DOI":"10.1080\/01431161.2016.1225182","article-title":"Development of a high-resolution aerial remote-sensing system for precision agriculture","volume":"38","author":"Bagheri","year":"2017","journal-title":"Int. J. Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3879","DOI":"10.5194\/hess-21-3879-2017","article-title":"The future of earth observation in hydrology","volume":"21","author":"McCabe","year":"2017","journal-title":"Hydrol. Earth Syst. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2296","DOI":"10.1080\/01431161.2016.1253900","article-title":"Identifying tree crown areas in undulating eucaluptus plantations using JSEG multi-scale segmentation and unmanned aerial vehicle near-infrared imagery","volume":"38","author":"Kang","year":"2017","journal-title":"Int. J. Remote Sens."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2392","DOI":"10.1080\/01431161.2016.1264028","article-title":"Determining tree height and crown diameter from high-resolution UAV imagery","volume":"38","author":"Panagiotidis","year":"2017","journal-title":"Int. J. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/j.eja.2014.01.004","article-title":"Tree height quantification using very high resolution imagery acquired from an unmanned aerial vehicle (UAV) and automatic 3D photo-reconstruction methods","volume":"55","author":"Angileri","year":"2014","journal-title":"Eur. J. Agron."},{"key":"ref_20","first-page":"79","article-title":"Combining UAV-based plant height from crop surface models, visible, and near infrared vegetation indices for biomass monitoring in barley","volume":"38","author":"Bendig","year":"2015","journal-title":"Geoinformation"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Oerke, E.-C., Gerhards, R., Menz, G., and Sikora, R.A. (2010). Precision Crop Protection\u2014The Challenge and Use of Heterogeneity, Springer.","DOI":"10.1007\/978-90-481-9277-9"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2150","DOI":"10.1080\/01431161.2016.1226002","article-title":"Assessment of a canopy height model (CHM) in a vineyard using UAV-based multispectral imaging","volume":"38","author":"Matese","year":"2017","journal-title":"Int. J. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"722","DOI":"10.1109\/TGRS.2008.2010457","article-title":"Thermal and narrowband multispectral remote sensing for vegetation monitoring from an unmanned aerial vehicle","volume":"47","author":"Berni","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"4213","DOI":"10.3390\/rs70404213","article-title":"High-resolution airborne UAV imagery to assess olive tree crown parameters using 3D photo reconstruction: Application in breeding trials","volume":"7","author":"Leon","year":"2015","journal-title":"Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Torres-Sanchez, J., Lopez-Granados, F., Serrano, N., Arquero, O., and Pena, J.M. (2015). High-throughput 3-D monitoring of agricultural-tree plantations with Unmanned Aerial Vehicle (UAV) technology. PLoS ONE.","DOI":"10.1371\/journal.pone.0130479"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"357","DOI":"10.14358\/PERS.72.4.357","article-title":"Detection of individual tree crowns in airborne Lidar data","volume":"72","author":"Koch","year":"2006","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"633","DOI":"10.5589\/m03-024","article-title":"Combined high-density lidar and multispectral imagery for individual tree crown analysis","volume":"29","author":"Leckie","year":"2003","journal-title":"Can. J. Remote Sens."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"322","DOI":"10.1016\/S0034-4257(02)00050-0","article-title":"Automated tree crown detection and delineation in high-resolution digital camera imagery of coniferous forest regeneration","volume":"82","author":"Pouliot","year":"2002","journal-title":"Remote Sens. Environ."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/j.rse.2005.12.015","article-title":"The delineation of tree crowns in Australian mixed species forests using hyperspectral Compact Airborne Spectrographic Imager (CASI) data","volume":"101","author":"Bunting","year":"2006","journal-title":"Remote Sens. Environ."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1080\/14498596.2010.494653","article-title":"Special Feature\u2014Geographic object-based image analysis","volume":"55","author":"Johansen","year":"2010","journal-title":"J. Spat. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"8261","DOI":"10.3390\/rs6098261","article-title":"Mapping banana plants from high spatial resolution orthophotos to facilitate eradication of Banana Bunchy Top Virus","volume":"6","author":"Johansen","year":"2014","journal-title":"Remote Sens."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"4753","DOI":"10.3390\/rs70404753","article-title":"Object-based approach for multi-scale mangrove composition mapping using multi-resolution image datasets","volume":"7","author":"Kamal","year":"2015","journal-title":"Remote Sens."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"4725","DOI":"10.1080\/01431161.2010.494184","article-title":"A review of methods for automatic individual tree-crown detection and delineation from passive remote sensing","volume":"32","author":"Kee","year":"2011","journal-title":"Int. J. Remote Sens."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1016\/j.isprsjprs.2009.06.004","article-title":"Object Based Image Analysis for Remote Sensing","volume":"65","author":"Blaschke","year":"2010","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"611","DOI":"10.14358\/PERS.76.6.661","article-title":"Acquisition, orthorectification, and object-based classification of unmanned aerial vehicle (UAV) imagery for rangeland monitoring","volume":"76","author":"Laliberte","year":"2010","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.isprsjprs.2014.12.026","article-title":"Training set size, scale, and features in Geographic Object-Based Image Analysis of very high resolution unmanned aerial vehicle imagery","volume":"102","author":"Ma","year":"2015","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/j.compag.2015.03.019","article-title":"An automatic object-based method for optimal thresholding in UAV images: Application for vegetation detection in herbaceous crops","volume":"114","author":"Pena","year":"2015","journal-title":"Comput. Electron. Agric."},{"key":"ref_38","unstructured":"Bureau of Meteorology (2018, March 19). Climate Statistics for Australian Locations, Available online: www.bom.gov.au\/climate\/averages\/tables\/cw_040854.shtml."},{"key":"ref_39","unstructured":"Scarth, P. (2003). A Methodology for Scaling Biophysical Models. [Ph.D. Thesis, The University of Queensland]."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1016\/S0168-1923(99)00018-0","article-title":"Leaf area index estimates obtained for clumped canopies using hemispherical photography","volume":"94","author":"Jackson","year":"1999","journal-title":"Agric. For. Meteorol."},{"key":"ref_41","unstructured":"Propeller (2018, March 19). AeroPoints. Available online: https:\/\/www.propelleraero.com\/aeropoints\/."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1876","DOI":"10.1109\/JSTARS.2015.2422716","article-title":"A simplified empirical line method of radiometric calibration for small Unmanned Aircraft Systems-based remote sensing","volume":"8","author":"Wang","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"2037","DOI":"10.1080\/01431161.2017.1294781","article-title":"Hierarchical land cover and vegetation classification using multispectral data acquired from an unmanned aerial vehicle","volume":"38","author":"Ahmed","year":"2017","journal-title":"Int. J. Remote Sens."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2953","DOI":"10.1080\/01431160500057764","article-title":"Quality assessment for geo-spatial objectis derived from remotely sensed data","volume":"26","author":"Zhan","year":"2005","journal-title":"Int. J. Remote Sens."},{"key":"ref_45","first-page":"849","article-title":"Using spatial co-occurrence texture to increase forest structure and species composition classification accuracy","volume":"67","author":"Franklin","year":"2001","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"610","DOI":"10.1109\/TSMC.1973.4309314","article-title":"Textural features for image classification","volume":"3","author":"Haralick","year":"1973","journal-title":"IEEE Trans. Syst. Man Cybern."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"45","DOI":"10.5589\/m02-004","article-title":"An analysis of co-occurrence texture statistics as a function of grey level quantization","volume":"28","author":"Clausi","year":"2002","journal-title":"Can. J. Remote Sens."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.rse.2007.02.014","article-title":"Application of high spatial resolution satellite imagery for riparian and forest ecosystem classification","volume":"110","author":"Johansen","year":"2007","journal-title":"Remote Sens. Environ."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"950","DOI":"10.3390\/rs4040950","article-title":"An international comparison of individual tree detection and extraction using airborne laser scanning","volume":"4","author":"Kaartinen","year":"2012","journal-title":"Remote Sens."},{"key":"ref_50","unstructured":"Lillesand, T., Kiefer, R.W., and Chipman, J. (2015). Remote Sensing and Image Interpretation, Wiley. [7th ed.]."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"71","DOI":"10.14358\/PERS.72.1.71","article-title":"Mapping structural parameters and species composition of riparian vegetation using IKONOS and Landsat ETM+ data in Australian tropical savannahs","volume":"72","author":"Johansen","year":"2006","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"733","DOI":"10.1080\/01431160512331316838","article-title":"The utility of texture analysis to improve per-pixel classification for high to very high spatial resolution imagery","volume":"26","author":"Puissant","year":"2005","journal-title":"Int. J. Remote Sens."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1016\/0034-4257(87)90015-0","article-title":"The factor of scale in remote sensing","volume":"21","author":"Woodcock","year":"1987","journal-title":"Remote Sens. Environ."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.ecolind.2013.01.041","article-title":"NDVI saturation adjustment: A new approach for improving cropland performance estimates in the Greater Platte River Basin, USA","volume":"30","author":"Gu","year":"2013","journal-title":"Ecol. Indic."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1890\/120150","article-title":"Lightweight unmanned aerial vehicles will revolutionize spatial ecology","volume":"11","author":"Anderson","year":"2013","journal-title":"Front. Ecol. Environ."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"281","DOI":"10.14358\/PERS.81.4.281","article-title":"Overview and current status of remote sensing applications based on unmanned aerial vehicles (UAVs)","volume":"81","author":"Pajares","year":"2015","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"1111","DOI":"10.3389\/fpls.2017.01111","article-title":"Unmanned aerial vehicle remote sensing for field-based crop phenotyping: Current status and perspectives","volume":"8","author":"Yang","year":"2017","journal-title":"Front. Plant Sci."},{"key":"ref_58","doi-asserted-by":"crossref","unstructured":"Robson, A., Rahman, M.M., and Muir, J. (2017). Using WorldView satellite imagery to map yield in avocado (Persea Americana): A case study in Bundaberg, Australia. Remote Sens., 9.","DOI":"10.3390\/rs9121223"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/6\/854\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:06:44Z","timestamp":1760195204000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/6\/854"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,6,1]]},"references-count":58,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2018,6]]}},"alternative-id":["rs10060854"],"URL":"https:\/\/doi.org\/10.3390\/rs10060854","relation":{"has-preprint":[{"id-type":"doi","id":"10.20944\/preprints201804.0198.v1","asserted-by":"object"}]},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,6,1]]}}}