Spelling suggestions: "subject:"ateologi"" "subject:"akeologi""
61 |
The Geochemistry of the Topsoil in Oslo, NorwayTijhuis, Laurentius January 2003 (has links)
In co-operation with the Geological Survey of Norway, 395 samples of topsoil, 44 bedrock samples and 24 samples of sand from sandboxes at kindergartens taken in Oslo, the capital city of Norway, were analysed for a wide range of elements. To get a measure on the bio-availability of arsenic, a five stage sequential extraction procedure was accomplished on a subset of 98 topsoil samples and on all 24 samples of sand from sandboxes. These fractions (i.e. “Exchangeable”, “Carbonate”, “Reducible substrate”, “Organic” and “Residual”) were analysed for arsenic. Bulk concentrations in a representative subset of 10 bedrock samples were determined by XRF analysis. For the concentrations of the elements As, B, Ba, Cd, Cr, Cu, Hg, Mn, Mo, Ni, P, Pb and Zn in soil, geologic sources are important, but human activity has had a large effect on concentrations in topsoil, especially in the central districts. At least 81% of the samples contain more arsenic than the Norm value for polluted soil used by the Norwegian authorities. For chromium, zinc and lead, the percentages are 65, 74 and 25 respectively. In topsoil, up to 50% of the arsenic is extractable in the exchangeable, the carbonate and the reducible substrate fractions, but only 2% of the samples exceeded the Norm value after the three extraction stages. After four stages of extraction, 69% of the samples exceeded the Norm value. At 24 kindergartens in the central districts of Oslo, concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn in topsoil samples are higher than in samples of sand from sandpits, but differences in arsenic are low. All topsoil samples and 63% of the sandbox samples exceed the arsenic Norm value for polluted soil used by the Norwegian authorities. Concentrations of at least one of the elements Cr, Cu, Ni, Pb and Zn exceed the Norm value in the topsoil. At two kindergartens all elements, except Cd, exceed the Norm value in the topsoil. In the samples from the sandboxes, arsenic concentrations in the exchangeable, the carbonate and the reducible substrate fractions, lie at a higher level than in topsoil samples. Leakage of arsenic compounds from impregnated and painted wood have probably caused elevated concentrations of this element in the sand. At two kindergartens the cumulative arsenic content in samples from the sandboxes exceeds the Norm value of 2 mg/kg As for polluted soil already after two fractions (i.e. the “Exchangeable” and the “Carbonate” fraction). After three fractions, the arsenic content in sand at 5 kindergartens exceeds this value. After four fractions this number was still 5. Regarding soil, no kindergartens had a cumulative arsenic content after three stages of the extraction procedure. After four stages 16 kindergartens contained more arsenic than the Norwegian Norm value of 2 mg/kg As. Bulk concentrations of metals, in the bedrock samples, are generally higher than the acid soluble concentrations. Differences are small for copper and zinc, somewhat higher for lead and nickel and considerably different for chromium. Acid soluble chromium concentrations in soil differ little when compared with acid soluble concentrations in bedrock, but are in general much lower than bulk concentrations in rock. Chromium is probably strongly incorporated in the mineral structure of rock samples and concentrated HNO3 cannot solubilize all chromium molecules. For copper, lead and zinc, the acid soluble concentrations in soil are higher than the bulk concentrations in bedrock. The parent rock material cannot be the only source for these elements in soils and various anthropogenic sources dispersed by air or water probably have major influence. The enrichment of nickel in topsoil near highways in Oslo might be due to the bitumen content of road dust. The enrichment of chromium and copper might be due to wear and tear of cars and engine parts. There is no enrichment of cadmium and zinc in topsoil near highways. Concentrations of zinc in topsoil in Oslo are generally high, most probably because of industry. The possible addition of zinc from traffic to the topsoil is not observed, in this study.
|
62 |
Analyse av ingeniørgeologiske problemstillinger for Vågsbygdporten / Analysis of engineering geological factors for the Vågsbygd road tunnelFjæran, Jørgen January 2012 (has links)
SammendragVågsbygdporten er en 1,3 km lang vegtunnel bestående av to hovedløp og tre ramper som tilsammen utgjør 3,3 km. Tunnelen bygges som del av prosjektet Fylkesveg 456 ny Vågsbygdvei iKristiansand kommune. Byggingen av tunnelen startet høsten 2010, og den forventes å væreferdigstilt i 2014. I oppgaven er det utført ingeniørgeologisk vurdering og analyse knyttet tilsammenheng mellom forhold i tunnel og forundersøkelser, bruk og nytteverdi avborparametertolkning (MWD) samt sikringsomfang i kryssområde.Med grunnlag i utførte forundersøkelser og ingeniørgeologisk tolkning er det gjort en sammenligningmed de kartlagte forholdene i tunnelen. Overensstemmelsen over 53 % av tunnellengden er god,mens den kun for 3 % av lengden er dårlig. Årsaken til de 3 % med dårlig overensstemmelse er sværtmye lavere fjellkvalitet enn antatt, og feiltolkning av svakhetssone i kryssområde mellomhovedtunneler og rampetunnel. Kartlagt bergklasse i tunnelen er jevnt over dårligere enn dentolkede.Omfanget av gjennomførte forundersøkelser har vært svært lik anbefalingen for vegtunneler isamme klasse, og kostnadene har kun vært 0,5 % lavere enn anbefalt. Derfor er omfanget vurdert tilå være tilstrekkelig for å oppnå en god ingeniørgeologisk oversikt før byggestart. Når det gjelderundersøkelser utført under driving er kostnadene av disse en del høyere enn tunneler som har værttilgjengelige for å sammenligne direkte med, men disse er til gjengjeld ti år gamle eller eldre.Analyse av MWD-tolkninger fra salvehull på prosjektet har vist at det er god overensstemmelsemellom disse og kartlegginger på stuff. Hele 72 % av tunnellengden er vurdert til å ha en god ellermeget god sammenheng. Et forsøk på å finne entydig sammenheng mellom tolkningen og Q-verdierhar gitt gode resultater. Nytteverdien av et slikt system på prosjektet har derimot vist seg å væresvært liten under driving. Dette skyldes i hovedsak lite bruk, en uvanlig løsning for geologiskoppfølging og kartlegging i tunnelen og jevnt over korte hullengder som gir liten mulighet for tolkninglengre frem enn en salvelengde. Systemet har likevel et stort potensial om forholdene leggesskikkelig til rette.I et krysningspunkt mellom hovedtunneler og rampetunnel er det gjort full utstøpning over en lengdepå til sammen 54 m. I dette området er det utført en empirisk analyse ved hjelp av Q-metoden, derkartlagte Q-verdier er justert systematisk for å havne i en sikringskategori tilfredsstillende nær utførtsikring. Resultatet fra analysen viser at en justering av SRF til mellom 12,5 og 25 i tillegg til en dobling av Jn gir det mest brukbare resultatet for justering av Q-verdi i et slikt område. Det er nødvendig å gjøre lignende analyser i andre tunnelprosjekter for å kunne bestemme om dette er en god eller dårlig tilnærming.
|
63 |
Digital kartlegging og 3D modellering av en geologisk forekomst / Digital Mapping and 3D Geological ModellingUlfstein, Nina January 2012 (has links)
I denne oppgaven presenteres teknologiske løsninger og arbeidsmetoder for utredningen av en skiferforekomst utenfor Sandane i Sogn og Fjordane. Forekomsten har store geologiske variasjoner, hvilket fører til problemer ved drift. Arbeidet med utredelsene er inndelt i tre artikler, som tar for seg de ulike aspektene av prosessen. Ut fra et behov for mer effektive og oppdaterte metoder for datainnsamling foreslås det i artikkel I en løsning for digital kartlegging ved bruk av ArcGIS Server og iPad. Denne innebærer lagring av data direkte til en geodatabase gjennom et interaktivt webkart, og ble brukt til kartlegging av skiferforekomsten. Erfaringene etter praktisk bruk i felt var positive, og løsningen førte til en effektivisering av arbeidsmetodikken.For å få mer kunnskap om de ulike bergartene og strukturene i skiferforekomsten er disse i beskrevet og analysert i artikkel II. Dette ble utført ved bruk av tradisjonelle geologiske undersøkelsesmetoder. Bergartene i forekomsten er analysert og klassifisert som kvartsskifer, meta-arkose og meta-diabas. Beskrivelser av strukturer i forekomsten og redegjørelse for tidligere arbeid i området er også inkludert. Dette er for å forstå utviklingen til området, og dermed forekomsten. Det ble utviklet en 3D modell av forekomsten som grunnlag for effektivisering av driften. Dette beskrives i artikkel III. Modellen er basert på overflatedataene innsamlet i felt, og bruker laserdata som rammeverk. Den ferdige 3D modellen av forekomsten viser hvor bergartene kvartsskifer, meta-arkose og meta-diabas kan lokaliseres på terrengoverflaten, og hvordan disse fortsetter inn i forekomsten. Ved å benytte seg av løsningen for digital kartlegging førte dette til mindre etterarbeid. Grunnen til dette var at observasjoner og målinger fra felt var lagret direkte i en geodatabase, som kunne brukes i et overordnet geografisk informasjonssystem. Dette førte til effektiv videre bruk til 3D modellering og visualiseringer. Ved å både utrede geologien på tradisjonelt, og modellere forekomsten i 3D, skapte dette en gjennomgående forståelse av forekomstens utstrekning, og hvordan den kan utnyttes.
|
64 |
Engineering geological assessment and structural comparison of the Vollan and Ivasnasen rock slopes at Sunndal, NorwayDreiås, Gudrun Majala January 2012 (has links)
This master thesis has interest in analyzing the two unstable rock slopes Ivasnasen and Vollan. These rock slopes are located in a U-shaped valley in Sunndal municipally (Møre & Romsdal, western Norway). The analyses are based on a combined approach using detailed geomorphic, structural and geological field mapping. This along with interpretation of high-resolution digital elevation models (DEM) and orthophotos, LIDAR-scans from one of the sites (Ivasnasen 2010 and 2011), numerical analysis, kinematic analysis, XRD analysis and laboratory testing. The two sites, Ivasnasen and Vollan are both unstable. Ivasnasen is classified with a historical rockslide and an unstable rock slope, this because a remaining unstable part is detected in the elongation of the back scarp for the historical rockslide. For Vollan an earlier event is still active. It is important to analyze both sides of the valley to get a best knowledge of the possible consequences and the history. The software Ante-Rockslide Topography (ART) is used to reconstruct and construct the topography for Ivasnasen. Detailed volume estimation is used further in the software Slope Local Base Level (SLBL) and a manual ART reconstruction in the PolyWork (software). The calculated volume estimates for the historical rockslide at Ivasnasen range from 5.2Mm3 -1.2Mm3 and from 0.6-2.1Mm3 for the unstable rock slope. The software Phase2 has been used for the numerical modeling. The reconstructed and constructed topography for Ivasnasen have been used for a detailed study of the parameters and trigger factors that affected the slope stability in Phase2.The back scarp at Vollan contains quartzite and the back scarp at Ivasnasen contains augen gneiss. The main failure mechanism is toppling at Vollan and planar sliding at Ivasnasen. The study of Vollan and Ivasnasen provides useful findings for the understanding of potential present rock slope instabilities.It has been concluded that it have been two different events at Ivasnasen, based on analyses that discovered two different back scarps. Due to the numerical modeling in Phase2 the main triggers at Ivasnasen is the groundwater table and most likely a progressive accumulation of rock weakening, where it also include rich biotite layers. A growing tension was build up in the cracks and the slope failed.For Vollan the analysis concludes that it is a really “slow movement” process acting. Due to the analyses that have been done until now shows that it cannot be characterized as significant movements. For this site it is important to do further investigations over a longer period to have a more determined conclusion. The analyses that have been done in this thesis can be used as good inputs to further investigations.
|
65 |
Från naturintresserad till statstjänsteman. : En studie över geologyrkets professionalisering i Sverige mellan 1858 och 1914.Backman, Carl-Magnus January 2014 (has links)
Uppkomsten av yrkesidentiteten geolog är i Sverige nära knutet till etableringen av Sveriges geologiska undersökning (SGU) år 1858. I denna uppsats undersöks hur geologens yrke utvecklades under perioden mellan 1858 till 1914, Yrket kom att professionaliseras som ett resultat av samverkan mellan SGU och svenska universitet och högskolor vilket beskrivs i uppsatsen. En genomgång har gjorts av bakgrund och arbetsuppgifter för de geologer som anställdes vid SGU under den aktuella prioden. Vidare beskrivs några praktiska geologiska arbetsuppgifter och vilken betydelse de hade för industrialiseringen av Sverige. SGUs engagemang i malmgeologiska frågor kom att ifrågasättas av värmländska bergsmän och den debatten behandlas även.
|
66 |
A sedimentological study of Cryogenian glacial-interglacial cycles recorded by the Port Askaig Tillite Formation on Islay, ScotlandDahlgren, Martin January 2018 (has links)
An interglacial mudstone sequence from the Port Askaig Tillite Formation on Islay was analysed using an Olympus XRF detector. The resulting geochemical log was compared with an XRF dataset acquired from a Quaternary sedimentary core from the Lomonosov Ridge in the Arctic Ocean. Chemical proxies representing climatic and environmental changes were analysed in an effort to specifically identify evidence of orbital forcing in the Cryogenian Period. The studied non-glacial rock-section from the Port Askaig Formation was interpreted as being deposited in a shallow marine setting at semitropical latitudes during an episode of global warming at some stage of the Sturtian glaciation (ca 717 – 660 Ma). The transport mechanism of glaciogenic material was by ice rafting. High hematite content was interpreted as an oxygenation event in a peritidal zone when isostatic rebound caused a sea level regression. Increasing amount of muscovite is interpreted to indicate increased weathering. Underlaying sequence of dolostone and overlaying sequence of sandstone were consistent with these interpretations. One interglacial phase is thus observed, which possibly could be attributed to Milankovitch orbital forcing. The interpretation of the paleoclimatic setting of the studied interglacial mudstone did not provide support for the Snowball Earth hypothesis in its “hard” version. Neither did other observations such as evidence of repeating glacial-interglacial cycles and banded iron formations (BIF) appearing also within the Sturtian glaciation.
|
67 |
Seismic tomography as an instrument for structural evaluation in the Printzsköld and Alliansen ore bodies, MalmbergetJonsson, Linus January 2017 (has links)
The Malmberget deposit is one of the major apatite iron ores in Europe, located in northern Norrbotten. As the mining in Malmberget proceeds deeper more challenges with the stability have been faced. When the stress distribution of a rock mass exceeds the rock strength energy in form of seismic waves is released. In Malmberget, a monitoring system consisting of 200 geophones is installed which detects all seismic waves in the area. Based on data received from the monitoring system, LKAB has achieved to generate a seismic tomography model over the velocity variations of the seismic waves as they propagate in the rock mass. The present study evaluates how the seismic tomography model can be used as a tool for reconstructing the structural characteristics of the two ore bodies Printzsköld and Alliansen. The aim is to clarify how seismic tomography can be combined with structural data to increase the geological knowledge of the Malmberget mining area. Based on structural measurements from the mine in combination with geotechnical data (RQD, Jr, Ja) two structural geological models were constructed. One model visualizing the orientation of the foliation and the other presenting brittle joints and fractures. The models were constructed in order to compare them with the seismic tomography model to outline structures and characteristics in the rock mass. The foliation in Printzsköld has a steep NE-SW orientation. In the eastern part where Printzsköld connects to Alliansen, the orientation changes to NW-SE, indicative of a fold structure. The joints and fractures in the study area appeared as 4 sets. One set appeared parallel to the foliation and one perpendicular to it. The two other sets were oriented E-W almost perpendicular to each other with a shallow dip. The rock quality in Printzsköld shows a pattern of increasing quality deeper down with zones of lower quality following the magnetite ore body. The previous identified deformation zone DZ031 appear as an important structure for unstable zones in Printzsköld. The current results suggest that the seismic tomography model needs more investigation but shows promising results as an indicative instrument delineating large scale structures and large zones with lower rock quality. / Gruvan i Malmberget är belägen i norra Norrbotten och utgör en av de största apatitjärnmalmerna i Europa. Med tiden försätter brytningen i Malmberget på allt större djup. Det innebär en större utmaning med stabiliteten i gruvan då spänningarna i berget kan tänkas öka längre ner. När bergsspänningarna överskrider bergets hållfasthet sker en frigörelse av energi i form av seismiska vågor. I Malmberget finns ett system av 200 geofoner som detekterar alla seismiska vågor i området. Baserat på data som mottagits från övervakningssystemet har LKAB lyckats framställa en seismisk tomografimodell över de seismiska vågornas hastighetsvariationer när de breder ut sig i bergmassan. I studien granskas hur den seismiska tomografin kan användas som ett verktyg för att utvärdera geologiska strukturer i de två malmkropparna Printzsköld och Alliansen. Syftet är att klargöra om seismisk tomografi kan kombineras med strukturdata för att öka den geologiska kunskapen i Malmbergets gruvområde. På basis av mätta strukturer i gruvan i kombination med geoteknisk data (RQD, Jr, Ja) konstruerades två strukturgeologiska modeller i syfte att jämföra modellerna mot den seismiska tomografin. Resultatet från studien visar att foliationen i Printzsköld har en NÖ-SV orientering med en brant stupning. I den östra delen som förbinder till Alliansen ändras orienteringen succesivt till NV-SÖ, vilket indikerar en veckning av foliationen. De dominerande riktningarna för sprickor och frakturer i Printzsköld och Alliansen uppträdde som 4 set. Ett set var orienterat parallellt med foliationen och ett vinkelrätt mot det förevarande. De två andra sprick riktningarna var orienterade Ö-V nästintill vinkelrätt mot varandra med en flack stupning. Bergskvalitén i Printzsköld visade ett mönster av att förbättras djupare ner. Zoner med lägre bergskvalité följer malmkroppen. Den seismiska tomografin uppvisade korrelation med storskaliga strukturer samt stora områden med minskad berghållfasthet. Den tidigare identifierade deformations zonen DZ031 uppträder också som en viktig struktur instabila områden i Printzsköld. Utvärderandet av resultaten tyder på att den seismiska tomografin behöver fortsatt mer undersökningsarbete men visar lovande resultat av att fungera som ett vägledande instrument för att definiera storskaliga strukturer och större områden med sämre bergskvalité.
|
68 |
Structural control on the Peña del Seo tungsten-greisen vein deposit, northwest SpainKronsell, Ida January 2019 (has links)
Tungsten is listed on the European Commission list of critical raw materials that are crucial to Europe’s economy. By raising awareness of tungsten as a critical raw material the EU can prioritise to enhance exploration, mining and recycling of tungsten. In this thesis the structural relationship between wall rock and veins, in a greisen-tungsten vein deposit, were analysed with the intention to interpret how tectonic deformation events control the emplacement of tungsten-bearing veins. The objective of this thesis is to investigate if and how structures controlled hydrothermal fluid flow and ore formation in the Peña del Seo tungsten-greisen vein deposit. Greisen systems are associated with tin and tungsten-bearing minerals and are related to intrusive magmatic bodies of granitic composition. Greisen-related granites (leucogranites), form at shallow depths in the crust (1.5-4 km) generally in intracontinental tectonic settings such as orogenic belts. The study site is located in the West Asturian-Leonese Zone in northwest Spain. This zone marks the transition between the foreland and the hinterland and is recognized as being part of a continental margin, where Palaeozoic rocks were deposited unconformably. These rocks were subsequently subjected to folding during the Variscan orogeny (370-290 Ma). Three main types of structures were generated due to three deformational phases (D1, D2 and D3) during the Variscan orogeny. D1 resulted in east-verging recumbent folding and formation of a related axial-planar parallel cleavage (S1), D2 resulted in displacement along large thrust sheets and D3 produced upright folding and refolding of F1 folds. Geological mapping with a focus on structural geology was carried out in March 2019, covering an area of approximately 0.25 km2. Structural measurements and oriented rock samples for microstructural study in thin sections were collected in the field. Additionally, photogrammetric mapping of structures was performed on a 3D photogrammetry model derived from a UAS survey. The geometry of the Peña del Seo tungsten-greisen vein deposit is interpreted to result from two major deformation events. The axial planar foliation (S1) at Peña del Seo is correlated to the regional fabric that developed during D1 of the Variscan orogeny. The related F1 folds are caused by buckling accompanied by flexural slip folding mechanism during D1. Forceful intrusion of the granite underlying the Peña del Seo deposit caused bending of the overlying rocks layers during D2. Layer-parallel stretching is likely to have caused tension fractures perpendicular to bedding in the outer arc of the F2 fold hinge. The formation of local crenulation and related spaced cleavage can be explained by layer-parallel shortening in the inner arc of the F2-fold. Local transposition of S1-foliation occurred during emplacement of quartz veins and explains the different orientation of strike of foliation between the northern and southern parts of the area. Fractures forming during formation of F2-fold are likely to have worked as conduits for ascending hydrothermal, ore-bearing fluids forming the Peña del Seo tungsten-greisen vein deposit.
|
69 |
How were high-pressure rocks exhumed in Naxos, Greece? / An Eocene/Oligocene blueschist-/greenschist-facies PT loop from Naxos Island, (Cyclades, Greece): Deformation-related re-equilibration vs thermal relaxationPeillod, Alexandre January 2016 (has links)
Combining petrological and geochronological data we were able to show that rocks in south Naxos completed a full blueschist-/greenschist-facies metamorphic loop in about 10 Myr, distinctly faster than hitherto believed. We show that the high-pressure rocks reached peak pressure (16.3±0.9 kbar - 619 ±32°C) between 40.5±1.0 and 38.3±0.5 Ma and were re-equilibrated in the middle crust (3.8±1.1 kbar - 384±30 °C) under greenschist-facies metamorphism during in the Oligocene ~32 Ma. Our data indicate that this exhumation occurred at rates of 7.4±4.6 km Ma-1. Therefore, the Oligocene greenschist-facies overprint of the blueschist-facies rocks from south Naxos is unrelated to the Miocene amphibolite-/greenschist-facies metamorphism observed in Naxos. / Genom att kombinera petrologiska och geokronologiska data kan vi visa att bergarter på södra Naxos fullföljt en fullständig blåskiffer-/grönskiffer-facies metamorfisk loop på 10 Ma. Detta är mycket snabbare änn vad man tidigare trott. Vi visar att högtrycks bergarter nådde maximalt tryck (16.3±0.9 kbar - 619 ±32°C) mellan 40.5±1.0 och 38.3±0.5 Ma och var åter i jämnvikt i mitten av jordskorpan (3.8±1.1 kbar - 384±30 °C) under grönskiffer-facies metamorfism under Oligocen vid ~32 Ma.Våra data visar att exhumeringen skedde med hastigheter av 7.4±4.6 km Ma-1. Därför är den Oligocena grönskiffer-facies ersättningen av blåskiffer-facies på södra Naxos ej relaterad till den Miocena amfibolit-/grönskiffer-facies som observerats på Naxos. / En combinant les données pétrologiques et géochronologiques, nous avons été en mesure de montrer que les roches du Sud Naxos ont effectué un trajet complet en métamorphisme schiste bleue/schiste vert en 10 Ma, distinctement plus rapide que ce qui était admis jusqu’alors. Nous montrons que les roches de haute pression ont atteint un pic de pression (16.3±0.9 kbar - 619 ±32°C) entre 40.5±1.0 et 38.3±0.5 Ma et ont été rééquilibrées en croûte moyenne (3.8±1.1 kbar - 384±30 °C) en métamorphisme de facies schiste vert pendant l’Oligocène ~32 Ma. Nos données indiquent que cette exhumation a une vitesse de 7.4±4.6 km Ma-1. Par conséquent, la surimpression des roches de haute pression en métamorphisme de facies schiste vert dans le sud de Naxos n’est pas à relier au métamorphisme de facies amphibolite/schiste vert du Miocène observé à Naxos.
|
70 |
Undersökning av markstödens betydelse för lägesnoggrannhet hos ortomosaik fotogrammetriskt genererade med UAV-bilder / Investigation of the importance of ground control points for positional accuracy in orthomosaic photogrammetrically generated with UAV-imagesBillenberg, Mathias, Persson, Jacob January 2022 (has links)
Syftet med examensarbetet är att undersöka markstödens placeringar och fördelningar i plan och om höjden har en inverkan på noggrannheten i ortomosaik. En jämförelse genomförs mellan totalstation och UAV-koordinater. Först utfördes rekognosering i fält för att sedan placera ut åtta stycken markstödsplattor varpå ett av markstöden blev placerad på en högre höjd. En ytterligare variant av markstödstyp placerades ut i form av ett grönt kryss med sprayflaska. Markstöden och kontrollpunkterna mättes in med totalstation efter fristationsuppställning där tre bakåtobjekt används för att erhålla noggranna plana koordinater. En fixpunkt används för att erhålla stabila höjder. I denna studie användes en UAV i form av DJI Phantom 4 Pro vid flygfotograferingen och en totalstation (Trimble S7) för inmätningarna. Inmätningen utfördes med totalstation mot kontrollpunkterna med samtliga markstöd som tillämpades sedan som facit. Slutligen utfördes UAV-flygning med en flygrutt på 60 m höjd och 90 graders vinkel för UAVkameran. Bildbearbetningen utfördes i programvaran Agisoft Metashape där fem stycken modeller genererades i form av ortomosaik och DEM. Sedan med hjälp av ortomosaiken exporterades koordinaterna till programvaran Microsoft Excel för vidare bearbetning och kontroll av avvikelser mellan UAV- och totalstationens koordinater. Resultaten från ortomosaikmodellerna visar att RMS i plan och höjd påverkas beroende på antalet markstöd. Modellen utan markstöd resulterar i en stor koordinatdifferens med RMS i plan på cirka 2 m. Vid användning av fyra markstöd ses en markant förbättring i noggrannhet för RMS i plan på cirka 0,008 m och i höjd på 0,045 m. För modellen med fem markstöd påvisas inga märkbara skillnader för RMS i plan, men för RMS i höjd erhålls betydligt lägre mätosäkerhet. Sista modellen med åtta markstöd resulterar i lägst mätosäkerhet i plan och höjd jämfört mot de andra modellerna, men skillnaden var oansenlig mellan fem och åtta markstöd. Utifrån frågeställningen och framtaget resultat kan det fastslås att ortomosaiksmodellen med fem markstöd är lämpligast för vidare användning vid flygfotografering. Markstödsplatta rekommenderas för noggrannare höjdkoordinater jämfört med märkspray. Om endast plana koordinater ska bearbetas kan antingen märkspray eller markstödsplatta utnyttjas för att erhålla likvärdigt resultat. / The objective of the bachelor thesis is to examine if ground control point (GCP) placing and allocation would impact the accuracy of an orthomosaic. A comparison between total station and UAV-coordinates is carried out. Reconnaissance was carried out in the field to deploy the GCP around the study area with one of them deployed on top of a pile. A different variant of GCP is deployed in the form of green-coloured cross that was applied with the help of a spray bottle. Both GCP and control points were measured with total station after the free station set-up where the three backsights and a fixed point were used to obtain a stable height. During the studies, a DJI Phantom 4 Pro UAV was used for aerial photography and a total station (Trimble S7) for the measurements. Before the flight, measurements were calculated with the total station to the control points and all GCP, which were then used as a record. GNSS-drone flying was performed with a flight route at a height of 60 meters and a 90 degrees angle for the UAV camera. Image processing was performed in software Agisoft Metashape where a total five orthomosaic models were generated. Then with the help of orthomosaic, the coordinates were transferred to the software Microsoft Excel for further processing and control of deviation between the coordinates of the UAV and the total station. Results from the orthomosaic models show that RMS in both plane and height do impact accuracy depending on the numbers of GCP used. A model without the use of GCP shows a huge coordinate difference for RMS in plane at approximately two meters. The use of four GCP models show a significant improvement in both RMS in plane at approximately 0,008 meters and the height at 0,046 meters. Five GCP models show a slight difference for RMS in plane but is considerable when the height was at 0,008 meters. Lastly, eight GCP models show some small significant improvements in both RMS plane and height. Based on the questions and results, it can be stated that the orthomosaic models with five GCP are recommended for further use of drone surveying. The GCP wooden plate is to be preferred for a more accurate height compared to the green cross spray method. But if only planar coordinates are considered, both GCP wooden plate and green cross spray bottle can be used with equal accuracy.
|
Page generated in 0.0608 seconds