applied sciences ArticleArticle KnudKnud RasmussenRasmussen GlacierGlacier StatusStatus AnalysisAnalysis BasedBased onon HistoricalHistorical DataData andand MovingMoving DetectionDetection UsingUsing RPASRPAS KarelKarel PavelkaPavelka **, Jaroslav, Jaroslav Šedina Šedina and and Karel Karel Pavelka Pavelka,, Jr Jr.. FacultyFaculty ofof CivilCivil Engineering,Engineering, CzechCzech TechnicalTechnical University University in in Prague, Prague, Thakurova Thakurova 7, 7, 16629 16629 Prague, Prague Czech, Republic; [email protected] Republic; [email protected] (J.Š.); [email protected] (J.Š.) [email protected] (K.P.J.) (K.P.J.) ** Correspondence:Correspondence: [email protected]; [email protected]; Tel.: Tel.: +420-608-211-360 +420-608-211-360 Abstract:Abstract: ThisThis articlearticle discussesdiscusses partialpartial resultsresults ofof anan internationalinternational scientificscientific expeditionexpedition toto GreenlandGreenland thatthat researchedresearched thethe geography,geography, geodesy,geodesy, botany,botany, andand glaciologyglaciology ofof thethe area.area. TheThe resultsresults herehere focusfocus onon the photogrammetrical results results obtained obtained with with the the eBee eBee drone drone in in the the eastern eastern part part ofof Greenland Greenland at atthe the front front of ofthe the Knud Knud Rasmussen Rasmussen Glacier Glacier and and the theuse useof archive of archive image image data data for monitoring for monitoring the con- the conditiondition of this of thisglacier glacier.. In these In theseshort- short-termterm visits to visits the site, to the the site, possibility the possibility of using ofa drone using is a discussed drone is discussedand the results and the show results not showonly the not flow only thespeed flow of speedthe glacier of the but glacier alsobut the alsoshape the and shape structure and structure from a fromheight a heightof up to of 200 up m. to From 200 m. two From overflights two overflights near the near glacier the front glacier at frontdifferent at different times, it times,was possible it was possibleto obtain to the obtain speed the of speed the glacier of the glacierflow and flow the and distribution the distribution of velocities of velocities in the in glacier the glacier stream. stream. The Thetechnology technology uses usesa comparison a comparison of two of point two pointclouds clouds derived derived from a fromset of aaerial set of photos aerial taken photos with taken the witheBee thedrone, eBee and drone, calculating and calculating the M3C2 the (M M3C2ultiscale (Multiscale Model-to- Model-to-ModelModel Cloud Comparison Cloud Comparison)) distances distanceswith CloudCompare with CloudCompare software. software.The results The correlate results correlatewith other with measurement other measurement methods methodslike accurate like accurateand long and-term long-term measurement measurement with Global with Global Navigation Navigation Satellite Satellite System System (GNSS (GNSS),), satellite satellite radar, radar, or orground ground geodetical geodetical technology. technology. The The resulting resulting speed speed from from the thedrone drone data data reached reached in the in middle the middle part partof the of glacier the glacier,, was wasapproximately approximately 12–15 12–15mm per day. per day.The second The second part partof the of paper the paper focuses focuses on the on anal- the analysisysis of modern of modern satellite satellite images images of the of Knud the Knud Rasmussen Rasmussen Glacier Glacier from fromGoogle Google Earth Earth(Landsat (Landsat series series1984–2016) 1984–2016) and Sentinel and Sentinel 2a, and 2a, a andcomparison a comparison with historical with historical aerial aerial images images from from1932 1932to 1933. to 1933. His- Citation: Pavelka, K.; Šedina, J.; Historicaltorical images images were were processed processed photogrammetrically photogrammetrically into into a athree three-dimensional-dimensional ( (3D)3D) model. Finally, Pavelka, K. Jr. Knud Rasmussen Citation: Pavelka, K.; Šedina, J.; orthogonalizedorthogonalized imageimage datadata fromfrom threethree systemssystems (drone(drone photos,photos, historicalhistorical aerialaerial photos,photos, andand satellitesatellite Glacier Status Analysis Based on Pavelka, K., Jr. Knud Rasmussen data)data) werewere comparedcompared inin thethe ArcGISArcGIS software.software. ThisThis allowsallows usus toto analyzeanalyze glacierglacier changeschanges overover timetime Historical Data and Moving Glacier Status Analysis Based on inin thethe timetime spanspan fromfrom 19321932 toto 2020,2020, withwith thethe caveatcaveat thatthat fromfrom 19331933 toto 19831983 wewe diddid notnot havehave datadata atat Detection Using RPAS. Appl. Sci. Historical Data and Moving Detection 2021, 11, x. ourour disposal.disposal. TheThe resultresult showsshows thatthat moremore significantsignificant changeschanges inin thethe areaarea ofof thisthis glacierglacier occurredoccurred afterafter Using RPAS. Appl. Sci. 2021, 11, 754. https://doi.org/10.3390/xxxxx 2011.2011. TheThe mainmain aimaim ofof thisthis articlearticle isis to research thethe useuse ofof photogrammetricphotogrammetric methodsmethods forfor monitoringmonitoring https://doi.org/10.3390/app11020754 thethe conditioncondition and and parameters parameters of of glaciers glaciers based based on on non-traditional non-traditional technology, technology such, such as drones as drones or new or Received: 30 November 2020 processingnew processing of historical of historical photos. photos. Received: 30 November 2020 Accepted: 12 January 2021 Accepted: 12 January 2021 Published: 14 January 2020 Keywords:Keywords: photogrammetry;photogrammetry; RPAS;RPAS; CloudCompare;CloudCompare; Bee;Bee; Greenland;Greenland; Knud Knud Rasmussen Rasmussen Glacier Glacier Published: 14 January 2021 Publisher’s Note: MDPI stays Publisher’s Note: MDPI stays neu- neutral with regard to jurisdictional tral with regard to jurisdictional clai- claims in published maps and 1. Introduction ms in published maps and institutio- 1. Introduction institutional affiliations. nal affiliations. II wouldwould likelike toto dedicatededicate thisthis articlearticle inin memoriam toto my friend,friend, scientist, and real man, ProfessorProfessor WilfriedWilfried KorthKorth (Figure(Figure1 ),1) who, who died died tragically tragically in in spring spring 2019, 2019, just just before before his his last last plannedplanned expeditionexpedition toto GreenlandGreenland(KP). (KP). Copyright: © 2021 by the authors. Copyright: © 2021 by the authors. Li- Submitted for possible open access censee MDPI, Basel, Switzerland. publication under the terms and This article is an open access article conditions of the Creative Commons distributed under the terms and con- Attribution (CC BY) license ditions of the Creative Commons At- (http://creativecommons.org/licenses tribution (CC BY) license (https:// /by/4.0/). creativecommons.org/licenses/by/ FigureFigure 1.1. ProfessorProfessor WilfriedWilfried KorthKorth (†(† 2019).2019). 4.0/). Appl. Sci. 2021, 11, x. https://doi.org/10.3390/xxxxx www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, 754. https://doi.org/10.3390/app11020754 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, x FOR PEER REVIEW 2 of 19 The gradual melting of glaciers has been monitored for a long time. Since the 1980s, ice has been declining more than it is replenished in winter. Winters are milder and sum- Appl. Sci. 2021, 11, 754 mers longer and warmer. The ice that disappears will not be restored. Nowadays,2 of 19six times more ice has been disappearing from Greenland than in the 1980s [1]. The Greenland cap is a vast mass of ice covering 1.7 million square km, which repre- sentsThe about gradual 80% meltingof Greenland of glaciers’s surface. has been It is monitoredthe second forlargest a long glaciated time. Since area the in the 1980s, world ice ; hasthe beenfirst decliningis the Antarctic morethan cap. itIts is thickness replenished is usually in winter. more Winters than are2 km milder and andsometimes summers ex- longerceeds and3 km warmer. [2]. The The weight ice that of disappearsthe glacier willhas com not bepressed restored. the Nowadays,central part six of timesGreenland, more icebringing has been the disappearing rocky bedrock from below Greenland it to about than insea the level, 1980s while [1]. the mountain range sur- roundsThe the Greenland glacier almost cap is a along vastmass its entire of ice edge. covering This 1.7is detectable million square by the km, deformation which repre- of sentsthe Earth about’s 80%gravity of Greenland’s field. If the entire surface. Greenland It is the secondcap melted, largest the glaciated level of the area world in the’s world;oceans thewould first isrise the by Antarctic about 7 m cap.. Due Its to thickness the long is-term usually melting more of than the 2 glacier, km and the sometimes compressed exceeds rock 3is km gradually [2]. The weightrising on of thethe glacier outskirts has compressedof Greenland. the According central part to of scientific Greenland, studies, bringing the theGreenland rocky bedrock coast rises below by 2 it.5 to cm about per year sea level,[3–5]. whileHowever, the mountainit is also scientifically range surrounds confirmed the glacierthat some almost parts along of the its glacier entire are edge. even This increasing. is detectable This byinformation the deformation indicates of that the Earth’sthe con- gravitydition of field.