{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T08:26:48Z","timestamp":1777537608813,"version":"3.51.4"},"reference-count":24,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,4,7]],"date-time":"2021-04-07T00:00:00Z","timestamp":1617753600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003130","name":"Fonds Wetenschappelijk Onderzoek","doi-asserted-by":"publisher","award":["S009319N"],"award-info":[{"award-number":["S009319N"]}],"id":[{"id":"10.13039\/501100003130","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Shape from focus is an accurate, but relatively time-consuming, 3D profilometry technique (compared to e.g., laser triangulation or fringe projection). This is the case because a large amount of data that needs to be captured and processed to obtain 3D measurements. In this paper, we propose a two-step shape-from-focus measurement approach that can improve the speed with 40%. By using a faster profilometry technique to create a coarse measurement of an unknown target, this coarse measurement can be used to limit the data capture to only the required frames. This method can significantly improve the measurement and processing speed. The method was tested on a 40 mm by 40 mm custom target and resulted in an overall 46% reduction of measurement time. The accuracy of the proposed method was compared against the conventional shape from focus method by comparing both methods with a more accurate reference.<\/jats:p>","DOI":"10.3390\/s21082574","type":"journal-article","created":{"date-parts":[[2021,4,7]],"date-time":"2021-04-07T03:52:03Z","timestamp":1617767523000},"page":"2574","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["A Fast Shape-from-Focus-Based Surface Topography Measurement Method"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9306-5078","authenticated-orcid":false,"given":"Jona","family":"Gladines","sequence":"first","affiliation":[{"name":"Faculty of Applied Engineering, University of Antwerp, 2020 Antwerp, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0590-2770","authenticated-orcid":false,"given":"Seppe","family":"Sels","sequence":"additional","affiliation":[{"name":"Faculty of Applied Engineering, University of Antwerp, 2020 Antwerp, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0510-8067","authenticated-orcid":false,"given":"Johan","family":"Blom","sequence":"additional","affiliation":[{"name":"Faculty of Applied Engineering, University of Antwerp, 2020 Antwerp, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7975-1338","authenticated-orcid":false,"given":"Steve","family":"Vanlanduit","sequence":"additional","affiliation":[{"name":"Faculty of Applied Engineering, University of Antwerp, 2020 Antwerp, Belgium"},{"name":"Department of Mechanical Engineering, Pleinlaan 2, Vrije Universiteit Brussel, 1050 Brussel, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,7]]},"reference":[{"key":"ref_1","first-page":"365","article-title":"Areal topography measurement of metal additive surfaces using focus variation microscopy","volume":"25","author":"Newton","year":"2019","journal-title":"Addit. Manuf."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Angot-Petit, L.J. (2017). Small scale surface profile recovery using a tunable lens based System. Electron. Imaging, 39\u201348.","DOI":"10.2352\/ISSN.2470-1173.2017.20.3DIPM-006"},{"key":"ref_3","unstructured":"Flack, D., and Hannaford, J. (2009). Fundamental Good Practice in Dimensional Metrology, National Physical Laboratory."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Kienle, P., Batarilo, L., Akg\u00fcl, M., K\u00f6hler, M.H., Wang, K., Jakobi, M., and Koch, A.W. (2020). Optical Setup for Error Compensation in a Laser Triangulation System. Sensors, 20.","DOI":"10.3390\/s20174949"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.optlaseng.2016.05.005","article-title":"Calibration procedure for a laser triangulation scanner with uncertainty evaluation","volume":"86","author":"Genta","year":"2016","journal-title":"Opt. Lasers Eng."},{"key":"ref_6","first-page":"696","article-title":"Investigating Laser Scanner Accuracy","volume":"34","author":"Boehler","year":"2003","journal-title":"Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1016\/j.optlaseng.2014.01.021","article-title":"Telecentric stereo micro-vision system: Calibration method and experiments","volume":"57","author":"Chen","year":"2014","journal-title":"Opt. Lasers Eng."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Cal\u00ec, M., and Ambu, R. (2018). Advanced 3D photogrammetric surface reconstruction of extensive objects by UAV camera image acquisition. Sensors, 18.","DOI":"10.3390\/s18092815"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"764","DOI":"10.1016\/j.proeng.2015.12.558","article-title":"Geometrical Verification based on a Laser Triangulation System in Industrial Environment. Effect of the Image Noise in the Measurement Results","volume":"Volume 132","author":"Brosed","year":"2015","journal-title":"Procedia Engineering"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Swojak, N., Wieczorowski, M., and Jakubowicz, M. (2021). Assessment of selected metrological properties of laser triangulation sensors. Meas. J. Int. Meas. Confed., 176.","DOI":"10.1016\/j.measurement.2021.109190"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"106192","DOI":"10.1016\/j.optlaseng.2020.106192","article-title":"Microscopic fringe projection profilometry: A review","volume":"135","author":"Hu","year":"2020","journal-title":"Opt. Lasers Eng."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1109\/TPAMI.1987.4767940","article-title":"A New Sense for Depth of Field","volume":"PAMI-9","author":"Pentland","year":"1987","journal-title":"IEEE Trans. Pattern Anal. Mach. Intell."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"5369","DOI":"10.1109\/TIP.2015.2479469","article-title":"Variational Depth from Focus Reconstruction","volume":"24","author":"Moeller","year":"2015","journal-title":"IEEE Trans. Image Process."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Mahmood, F., Mahmood, M.T., and Iqbal, J. (2017, January 18\u201321). 3-D shape recovery from image focus using no-reference sharpness metric based on inherent sharpness. Proceedings of the International Conference on Control, Automation and Systems, Jeju, Korea.","DOI":"10.23919\/ICCAS.2017.8204453"},{"key":"ref_15","unstructured":"Optotune (2019, September 19). Fast Electrically Tunable Lens EL-10-30 Series. Available online: https:\/\/www.optotune.com\/s\/Optotune-EL-10-30.pdf."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1415","DOI":"10.1016\/j.patcog.2012.11.011","article-title":"Analysis of focus measure operators for shape-from-focus","volume":"46","author":"Pertuz","year":"2013","journal-title":"Pattern Recognit."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Hazirbas, C., Soyer, S.G., Staab, M.C., Leal-Taix\u00e9, L., and Cremers, D. (2018, January 2\u20136). Deep Depth from Focus. Proceedings of the Asian Conference on Computer Vision (ACCV 2018), Perth, WA, Australia.","DOI":"10.1007\/978-3-030-20893-6_33"},{"key":"ref_18","unstructured":"Fialka, O., and \u010cad\u00edk, M. (2006, January 5\u20137). FFT and convolution performance in image filtering on GPU. Proceedings of the 10th International Conference on Information Visualisation (IV 2006), London, UK."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Chen, X., Qiu, Y., and Yi, H. (2013, January 9\u201311). Implementation and performance of image filtering on GPU. Proceedings of the 2013 International Conference on Intelligent Control and Information Processing (ICICIP 2013), Beijing, China.","DOI":"10.1109\/ICICIP.2013.6568129"},{"key":"ref_20","unstructured":"Pertuz, S. (2019, July 24). Shape from Focus. Available online: https:\/\/nl.mathworks.com\/matlabcentral\/fileexchange\/55103-shape-from-focus."},{"key":"ref_21","unstructured":"Movimed (2020, August 07). What Is Laser Triangulation?. Available online: https:\/\/www.movimed.com\/knowledgebase\/what-is-laser-triangulation\/."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"12782","DOI":"10.3390\/s150612782","article-title":"A rapid method to achieve aero-engine blade form detection","volume":"15","author":"Sun","year":"2015","journal-title":"Sensors"},{"key":"ref_23","first-page":"30","article-title":"Change detection on points cloud data acquired with a ground laser scanner","volume":"36","author":"Roux","year":"2005","journal-title":"Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. ISPRS Arch."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Rajendra, Y.D., Mehrotra, S.C., Kale, K.V., Manza, R.R., Dhumal, R.K., Nagne, A.D., Vibhute, D., Ramanujan, S., and Chair, G. (2014). Evaluation of Partially Overlapping 3D Point Cloud\u2019s Registration by Using ICP Variant and Cloudcompare. Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci., 891\u2013897.","DOI":"10.5194\/isprsarchives-XL-8-891-2014"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/8\/2574\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T13:26:26Z","timestamp":1760361986000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/8\/2574"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,4,7]]},"references-count":24,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2021,4]]}},"alternative-id":["s21082574"],"URL":"https:\/\/doi.org\/10.3390\/s21082574","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,4,7]]}}}