{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T19:16:03Z","timestamp":1781723763131,"version":"3.54.5"},"reference-count":37,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2019,5,27]],"date-time":"2019-05-27T00:00:00Z","timestamp":1558915200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010571","name":"Bundesministerium f\u00fcr Bildung, Wissenschaft, Forschung und Technologie","doi-asserted-by":"publisher","award":["033RK046A"],"award-info":[{"award-number":["033RK046A"]}],"id":[{"id":"10.13039\/501100010571","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100010665","name":"H2020 Marie Sk\u0142odowska-Curie Actions","doi-asserted-by":"publisher","award":["778322"],"award-info":[{"award-number":["778322"]}],"id":[{"id":"10.13039\/100010665","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Recent technical advances in drones make them increasingly relevant and important tools for forest measurements. However, information on how to optimally set flight parameters and choose sensor resolution is lagging behind the technical developments. Our study aims to address this gap, exploring the effects of drone flight parameters (altitude, image overlap, and sensor resolution) on image reconstruction and successful 3D point extraction. This study was conducted using video footage obtained from flights at several altitudes, sampled for images at varying frequencies to obtain forward overlap ratios ranging between 91 and 99%. Artificial reduction of image resolution was used to simulate sensor resolutions between 0.3 and 8.3 Megapixels (Mpx). The resulting data matrix was analysed using commercial multi-view reconstruction (MVG) software to understand the effects of drone variables on (1) reconstruction detail and precision, (2) flight times of the drone, and (3) reconstruction times during data processing. The correlations between variables were statistically analysed with a multivariate generalised additive model (GAM), based on a tensor spline smoother to construct response surfaces. Flight time was linearly related to altitude, while processing time was mainly influenced by altitude and forward overlap, which in turn changed the number of images processed. Low flight altitudes yielded the highest reconstruction details and best precision, particularly in combination with high image overlaps. Interestingly, this effect was nonlinear and not directly related to increased sensor resolution at higher altitudes. We suggest that image geometry and high image frequency enable the MVG algorithm to identify more points on the silhouettes of tree crowns. Our results are some of the first estimates of reasonable value ranges for flight parameter selection for forestry applications.<\/jats:p>","DOI":"10.3390\/rs11101252","type":"journal-article","created":{"date-parts":[[2019,5,27]],"date-time":"2019-05-27T11:19:27Z","timestamp":1558955967000},"page":"1252","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":172,"title":["Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7348-9810","authenticated-orcid":false,"given":"Erich","family":"Seifert","sequence":"first","affiliation":[{"name":"Department of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South Africa"},{"name":"Scientes Mondium UG, 85250 Altom\u00fcnster, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefan","family":"Seifert","sequence":"additional","affiliation":[{"name":"Scientes Mondium UG, 85250 Altom\u00fcnster, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Holger","family":"Vogt","sequence":"additional","affiliation":[{"name":"Cartography, GIS and Remote Sensing Department, Institute of Geography, Universit\u00e4t G\u00f6ttingen, 37077 G\u00f6ttingen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8493-2507","authenticated-orcid":false,"given":"David","family":"Drew","sequence":"additional","affiliation":[{"name":"Department of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3036-0088","authenticated-orcid":false,"given":"Jan","family":"van Aardt","sequence":"additional","affiliation":[{"name":"Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, Rochester, NY 14623, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anton","family":"Kunneke","sequence":"additional","affiliation":[{"name":"Department of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9611-6272","authenticated-orcid":false,"given":"Thomas","family":"Seifert","sequence":"additional","affiliation":[{"name":"Department of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South Africa"},{"name":"Scientes Mondium UG, 85250 Altom\u00fcnster, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"71","DOI":"10.5558\/tfc2017-012","article-title":"Unmanned aerial systems for precision forest inventory purposes: A review and case study","volume":"93","author":"Goodbody","year":"2017","journal-title":"For. Chron."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2427","DOI":"10.1080\/01431161.2016.1252477","article-title":"Forestry applications of UAVs in Europe: A review","volume":"38","author":"Torresan","year":"2017","journal-title":"Int. J. Remote Sens."},{"key":"ref_3","unstructured":"International Union of Forest Research Organizations (2019, March 01). Scientific Summary No. 19. Available online: https:\/\/www.iufro.org\/publications\/summaries\/article\/2006\/05\/31\/scientific-summary-no-19\/."},{"key":"ref_4","unstructured":"Ackerman, P.A., Ham, H., and Lu, C. (2010). Integrating terrestrial laser scanning based inventory with sawing simulation. Developments in Precision Forestry Since 2006, Proceedings of the International Precision Forestry Symposium, Stellenbosch University, Stellenbosch, South Africa, 1\u20133 March 2010, Department of Forest and Wood Science."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"245","DOI":"10.14358\/PERS.79.3.245","article-title":"Comparison of Forest Attributes Derived from Two Terrestrial Lidar Systems","volume":"79","author":"Ducey","year":"2013","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1682","DOI":"10.3390\/f5071682","article-title":"Outlook for the Next Generation\u2019s Precision Forestry in Finland","volume":"5","author":"Holopainen","year":"2014","journal-title":"Forests"},{"key":"ref_7","unstructured":"Seifert, T. (2014). Localisation of Biomass Potentials. Bioenergy from Wood: Sustainable Production in the Tropics, Springer."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"11051","DOI":"10.3390\/rs61111051","article-title":"UAV Flight Experiments Applied to the Remote Sensing of Vegetated Areas","volume":"6","author":"Barrado","year":"2014","journal-title":"Remote Sens."},{"key":"ref_9","first-page":"45","article-title":"The Practical Application of UAV-Based Photogrammetry under Economic Aspects","volume":"38","author":"Sauerbier","year":"2011","journal-title":"ISPRS Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1519","DOI":"10.3390\/rs4061519","article-title":"Development of a UAV-LiDAR System with Application to Forest Inventory","volume":"4","author":"Wallace","year":"2012","journal-title":"Remote Sens."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.3390\/rs4061671","article-title":"Unmanned Aircraft Systems in Remote Sensing and Scientific Research: Classification and Considerations of Use","volume":"4","author":"Watts","year":"2012","journal-title":"Remote Sens."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1243","DOI":"10.1080\/01431160701736513","article-title":"High-quality image matching and automated generation of 3D tree models","volume":"29","author":"Baltsavias","year":"2008","journal-title":"Int. J. Remote Sens."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1123","DOI":"10.14358\/PERS.76.10.1123","article-title":"Point Clouds","volume":"76","author":"Leberl","year":"2010","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"518","DOI":"10.3390\/f4030518","article-title":"The Utility of Image-Based Point Clouds for Forest Inventory: A Comparison with Airborne Laser Scanning","volume":"4","author":"White","year":"2013","journal-title":"Forests"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"99","DOI":"10.2747\/1548-1603.48.1.99","article-title":"Small-Scale Unmanned Aerial Vehicles in Environmental Remote Sensing: Challenges and Opportunities","volume":"48","author":"Hardin","year":"2011","journal-title":"GIScience Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1139\/juvs-2014-0006","article-title":"Remote sensing of the environment with small unmanned aircraft systems (UASs), part 1: A review of progress and challenges","volume":"2","author":"Whitehead","year":"2014","journal-title":"J. Unmanned Veh. Syst."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Fritz, A., Kattenborn, T., and Koch, B. (2013). UAV-based photogrammetric point clouds\u2014Tree stem mapping in open stands in comparison to terrestrial laser scanner point clouds. ISPRS Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci., 141\u2013146.","DOI":"10.5194\/isprsarchives-XL-1-W2-141-2013"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Nesbit, P.R., and Hugenholtz, C.H. (2019). Enhancing UAV\u2013SfM 3D Model Accuracy in High-Relief Landscapes by Incorporating Oblique Images. Remote Sens., 11.","DOI":"10.3390\/rs11030239"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"514","DOI":"10.1016\/j.isprsjprs.2010.08.002","article-title":"A low-cost multi-sensoral mobile mapping system and its feasibility for tree measurements","volume":"65","author":"Jaakkola","year":"2010","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"259","DOI":"10.1016\/j.rse.2013.04.005","article-title":"High spatial resolution three-dimensional mapping of vegetation spectral dynamics using computer vision","volume":"136","author":"Dandois","year":"2013","journal-title":"Remote Sens. Environ."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Wallace, L., Lucieer, A., Malenovsk\u00fd, Z., Turner, D., and Vop\u011bnka, P. (2016). Assessment of Forest Structure Using Two UAV Techniques: A Comparison of Airborne Laser Scanning and Structure from Motion (SfM) Point Clouds. Forests, 7.","DOI":"10.3390\/f7030062"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1139\/X08-188","article-title":"Effects of height imputation strategies on stand volume estimation","volume":"39","author":"Garber","year":"2009","journal-title":"Can. J. For. Res."},{"key":"ref_23","unstructured":"Seifert, T. (2014). Modelling and Simulation of Tree Biomass. Bioenergy from Wood: Sustainable Production in the Tropics, Springer."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.foreco.2017.12.030","article-title":"Height\u2013Diameter allometry in South Africa\u2019s indigenous high forests: Assessing generic models performance and function forms","volume":"410","author":"Mensah","year":"2018","journal-title":"For. Ecol. Manag."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1513","DOI":"10.1007\/s10980-012-9806-4","article-title":"Modeling acoustic diversity using soundscape recordings and LIDAR-derived metrics of vertical forest structure in a neotropical rainforest","volume":"27","author":"Pekin","year":"2012","journal-title":"Landsc. Ecol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1016\/j.foreco.2013.06.043","article-title":"From ground to above canopy\u2014Bat activity in mature forests is driven by vegetation density and height","volume":"306","author":"Brandl","year":"2013","journal-title":"For. Ecol. Manag."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1186\/s40663-014-0013-4","article-title":"Competition effects in an afrotemperate forest","volume":"1","author":"Seifert","year":"2014","journal-title":"For. Ecosyst."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1007\/s40725-019-00087-2","article-title":"Digital Aerial Photogrammetry for Updating Area-Based Forest Inventories: A Review of Opportunities, Challenges, and Future Directions","volume":"5","author":"Goodbody","year":"2019","journal-title":"Curr. For. Rep."},{"key":"ref_29","unstructured":"Falkner, E., and Morgan, D. (2002). Aerial Mapping: Methods and Applications, CRC Press. [2nd ed.]."},{"key":"ref_30","unstructured":"Leachtenauer, J.C., and Driggers, R.G. (2001). Surveillance and Reconnaissance Imaging Systems: Modeling and Performance Prediction, Artech House."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"13895","DOI":"10.3390\/rs71013895","article-title":"Optimal Altitude, Overlap, and Weather Conditions for Computer Vision UAV Estimates of Forest Structure","volume":"7","author":"Dandois","year":"2015","journal-title":"Remote Sens."},{"key":"ref_32","unstructured":"Frey, J., Kovach, K., Stemmler, S., and Koch, B. (2018). UAV Photogrammetry of Forests as a Vulnerable Process. A Sensitivity Analysis for a Structure from Motion RGB-Image Pipeline. Remote Sens., 10."},{"key":"ref_33","unstructured":"CloudCompare Team (2019, March 01). CloudCompare: 3D Point Cloud and Mesh Processing Software. Available online: http:\/\/www.cloudcompare.org\/."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1111\/j.1467-9868.2010.00749.x","article-title":"Fast stable restricted maximum likelihood and marginal likelihood estimation of semiparametric generalized linear models","volume":"73","author":"Wood","year":"2011","journal-title":"J. R. Stat. Soc. Ser. B Stat. Methodol."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Zuur, A., Ieno, E.N., Walker, N., Saveiliev, A.A., and Smith, G.M. (2009). Mixed Effects Models and Extensions in Ecology with R, Springer.","DOI":"10.1007\/978-0-387-87458-6"},{"key":"ref_36","unstructured":"R Core Team (2018). R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1007\/s11119-017-9502-0","article-title":"Assessing UAV-collected image overlap influence on computation time and digital surface model accuracy in olive orchards","volume":"19","year":"2018","journal-title":"Precis. Agric."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/10\/1252\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:55:28Z","timestamp":1760187328000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/10\/1252"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,5,27]]},"references-count":37,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2019,5]]}},"alternative-id":["rs11101252"],"URL":"https:\/\/doi.org\/10.3390\/rs11101252","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,5,27]]}}}