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3D laser scanning as a tool for Viking Age studiesNeiß (Neiss), Michael, Sabrina B., Sholts, Wärmländer, Sebastian K.T.S. January 2013 (has links)
Three-dimensional (3D) laser scanners are becoming increasingly more affordable and user-friendly, making 3D-modeling tools more widely available to researchers in various countries and disciplines. In archaeology, 3D-modeling has the particular advantages of facilitating the documentation and analysis of objects that are fragile, rare, and often difficult to access. We have previously shown that 3D-modeling is a highly useful tool for shape analysis of archaeological bone material, due to the high measurement accuracy inherent in the latest generation of 3D laser scanners (Sholts et al. 2010; 2011). In this work, we explore the utility of 3D-modeling as a tool for Viking Age artefact analysis. To test the usefulness of 3D-modeling when analyzing artefacts with a very complex morphology, we chose highly ornate Viking Age baroque shaped brooches as study objects. These baroque shaped brooches constitute a group of dress ornaments mainly encountered in eastern Viking Age Scandinavia. Due to their large cast and/or attached bosses they obtain an almost baroque appearance, hence their name (cf. Jansson 1984: p. 81). They appear in two major versions, i.e. circular or equal armed, and in two kinds of material, i.e. silver- and copper-based alloys. Because of the position of bronze brooches in burial contexts, it appears they were used to fasten the cape or shawl in the female dress (cf. Jansson 1984: p. 75ff., Aagård 1984: p. 96ff.; Neiß 2006, figs. 3, 4; Capelle 1962: p. 106). For the present work a recently excavated brooch from Denmark was analyzed, together with three Russian brooches with nearly iconic status in the field of Viking Age studies. In the three case studies, we investigated possible uses of 3D-modeling for artefact analysis, artefact reconstruction, and tool mark and motif analysis. Exploring the usefulness of 3D-modeling for these purposes allowed us to draw conclusions regarding how 3D-analysis can be best incorporated into future artefact analysis. In addition, the case studies allowed us to gain new insights about the baroque shaped brooches and their uses. / <p>Forskningsfinansiärer: Helge Ax:son Johnsons stiftelse, Svenska institutet (Visby-programmet), Kungliga vitterhets historie och antikvitets akademin (Montelius minnesfond); Svenska fornminnesforeningen</p> / 3D-laserskanning som verktyg vid vikingatidsstudier
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Towards deep unsupervised inverse graphicsParent-Lévesque, Jérôme 12 1900 (has links)
Un objectif de longue date dans le domaine de la vision par ordinateur est de déduire le
contenu 3D d’une scène à partir d’une seule photo, une tâche connue sous le nom d’inverse
graphics. L’apprentissage automatique a, dans les dernières années, permis à de nombreuses
approches de faire de grands progrès vers la résolution de ce problème. Cependant, la plupart
de ces approches requièrent des données de supervision 3D qui sont coûteuses et parfois
impossible à obtenir, ce qui limite les capacités d’apprentissage de telles œuvres. Dans
ce travail, nous explorons l’architecture des méthodes d’inverse graphics non-supervisées
et proposons deux méthodes basées sur des représentations 3D et algorithmes de rendus
différentiables distincts: les surfels ainsi qu’une nouvelle représentation basée sur Voronoï.
Dans la première méthode basée sur les surfels, nous montrons que, bien qu’efficace pour
maintenir la cohérence visuelle, la production de surfels à l’aide d’une carte de profondeur
apprise entraîne des ambiguïtés car la relation entre la carte de profondeur et le rendu n’est
pas bijective. Dans notre deuxième méthode, nous introduisons une nouvelle représentation
3D basée sur les diagrammes de Voronoï qui modélise des objets/scènes à la fois explicitement
et implicitement, combinant ainsi les avantages des deux approches. Nous montrons comment
cette représentation peut être utilisée à la fois dans un contexte supervisé et non-supervisé
et discutons de ses avantages par rapport aux représentations 3D traditionnelles / A long standing goal of computer vision is to infer the underlying 3D content in a scene from
a single photograph, a task known as inverse graphics. Machine learning has, in recent years,
enabled many approaches to make great progress towards solving this problem. However,
most approaches rely on 3D supervision data which is expensive and sometimes impossible
to obtain and therefore limits the learning capabilities of such work. In this work, we explore
the deep unsupervised inverse graphics training pipeline and propose two methods based on
distinct 3D representations and associated differentiable rendering algorithms: namely surfels
and a novel Voronoi-based representation. In the first method based on surfels, we show that,
while effective at maintaining view-consistency, producing view-dependent surfels using a
learned depth map results in ambiguities as the mapping between depth map and rendering
is non-bijective. In our second method, we introduce a novel 3D representation based on
Voronoi diagrams which models objects/scenes both explicitly and implicitly simultaneously,
thereby combining the benefits of both. We show how this representation can be used in both
a supervised and unsupervised context and discuss its advantages compared to traditional
3D representations.
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Jämförelse av punktmoln genererade med terrester laserskanner och drönar-baserad Structure-from-Motion fotogrammetri : En studie om osäkerhet och kvalitet vid detaljmätning och 3D-modellering / Comparison of Point Clouds Generated by Terrestrial Laser Scanning and Structure-from-Motion Photogrammetry with UAVs : A study on uncertainty and quality in detailed measurement and 3D modelingNyberg, Emil, Wolski, Alexander January 2024 (has links)
Fotogrammetri är en viktig metod för att skapa 3D-representationer av terräng och strukturer, men utmaningar kvarstår när det gäller noggrannheten på grund av faktorer som bildkvalitet, kamerakalibrering och positionsdata. Användningen av drönare för byggnadsdetaljmätning möjliggör snabb och kostnadseffektiv datainsamling, men noggrannheten kan påverkas av bildkvalitet och skuggning. Avhandlingen syftar till att jämföra noggrannheten och kvaliteten hos punktmoln genererade med två olika tekniker: terrester laserskanning (TLS) och struktur-från-rörelse (SfM) fotogrammetri med drönare. För att testa båda metodernas osäkerhet och noggrannhet vid detaljmätning av bostäder. Genom att utföra mätningar på en villa har data samlats in med både TLS och drönare utrustade med 48 MP kamera, samt georeferering med markstöd (GCP). SfM-punktmoln bearbetades med Agisoft Metashape. Jämförelser gjordes mellan SfM- och TLS-punktmoln avseende täckning, lägesskillnad och lägesosäkerhet. Genom att följa riktlinjer från HMK - Terrester Laserskanning och tillämpa HMK Standardnivå 3 säkerställs hög noggrannhet i mätningarna. Kontroll av lägesosäkerhet av båda punktmolnen resulterade i en lägesosäkerhet som understeg toleranser satta enligt HMK - Terrester laserskanner Standardnivå 3. Kontrollen av lägesosäkerheten visade att kvadratiska medelfelet(RMSE) i plan och höjd var 0.011m respektive 0.007m för TLS-punktmolnet, och 0.02m respektive 0.015m för drönar-SfM-punktmolnet, vilket låg under toleransen enligt HMK- Terrester Detaljmätning 2021. Resultaten tyder på att Structure-from-Motion fotogrammetri med drönare kan generera punktmoln med god detaljrikedom, inte lika noggrann som med terrester laserskanner på sin lägsta inställning. TLS uppvisade mindre osäkerhet enligt kontrollen av lägesosäkerhet, ungefär en halvering av RMSE i både plan och höjd. I studien framgick det att TLS presterar sämre vid svåråtkomliga ytor med skymd sikt och ogynnsamma infallsvinklar, där effekten blir en lägre punkttäthet för punktmolnet. Vid gynnsamma förhållanden erbjuder TLS en högre noggrannhet och detaljnivå jämfört med SfM punktmoln. Enligt M3C2 punktmoln analys, med TLS punktmolnet som referens, antydde det att SfM punktmolnet genererade största felen vid takfot samt vid buskage. De större felen vid takfot tyder på att SfM presterar sämre gällande detaljnivå och fel vid buskageområdet varierar inte från det som dokumenterats om fotogrammetriska fel vid mappning av vegetation. SfM kan utföra en effektiv datainsamling för större samt svåråtkomliga ytor men kräver lång bearbetningstid med diverse hjälpmedel för att uppnå hög noggrannhet. TLS kräver istället en lång datainsamlingsprocess men kan generera ett detaljerat och noggrant punktmoln direkt utan långa bearbetningsprocesser. Val av metod styrs därmed baserat på specifika projektkrav. Långsiktiga implikationer inkluderar förbättrad effektivitet och säkerhet inom bygg- och anläggningsprojekt, samt potentialen för kostnadsbesparingar och mer detaljerade inspektioner. / Photogrammetry is a crucial method for creating 3D representations of terrain and structures, yet challenges remain regarding accuracy due to factors such as image quality, camera calibration, and positional data. The use of drones for building detail measurements enables rapid and cost-effective data collection, but accuracy can be affected by image quality and shading. This thesis aims to compare the accuracy and quality of point clouds generated using two different techniques: terrestrial laser scanning (TLS) and Structure-from-Motion (SfM) photogrammetry with drones. The objective is to test the uncertainty and accuracy of both methods in residential surveying. Data collection was performed on a villa using both TLS and a drone equipped with a 48 MP camera, along with georeferencing with ground control points (GCP). SfM point clouds were processed with Agisoft Metashape. Comparisons were made between SfM and TLS point clouds in terms of coverage, positional difference, and positional uncertainty. By following guidelines from HMK - Terrester laserskanning 2021 and applying HMK Standard Level 3, high measurement accuracy was ensured. Positional uncertainty checks of both point clouds resulted in positional uncertainty within tolerances set by HMK - Terrestrial Laser Scanning Standard Level 3. The positional uncertainty, with a sample of 41 points showed that the root mean square error (RMSE) in plane and height was 0.011m and 0.007m respectively for the TLS point cloud, and 0.02m and 0.015m for the drone-SfM point cloud, both within the tolerance according to HMK - Terrestrial Detail Measurement 2021. The results suggest that Structure-from-Motion photogrammetry with drones can generate point clouds with good detail, although not as accurate as terrestrial laser scanning at its lowest setting. TLS showed less uncertainty according to the positional uncertainty check, with approximately half the RMSE in both plan and height. The study found that TLS performs worse on difficult-to-access surfaces with obstructed views and unfavorable angles, resulting in lower point cloud density. Under favorable conditions, TLS offers higher accuracy and detail compared to SfM point clouds. According to M3C2 point cloud analysis, using the TLS point cloud as a reference, SfM point clouds showed the largest errors at eaves and shrubbery. The larger errors at eaves indicate that SfM performs worse in terms of detail level, and errors in the shrubbery area are consistent with documented photogrammetric errors in vegetation mapping. SfM can effectively collect data for larger and difficult-to-access areas but requires extensive processing time with various aids to achieve high accuracy. Conversely, TLS requires a long data collection process but can generate a detailed and accurate point cloud directly without lengthy processing. The choice of method thus depends on specific project requirements. Long-term implications include improved efficiency and safety in construction and infrastructure projects, as well as potential cost savings and more detailed inspections.
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Does The Third-Dimension Play A Role in Shaping Urban Thermal Conditions?Alavi Panah, Seyed Sadroddin 21 February 2019 (has links)
Zahlreiche Studien den Stand der Forschung in Bezug auf die Ökosystemdienstleistungen untersucht. Dennoch wurde die Dimension „Volumen und Höhe“, d.h. die dritte Dimension städtischer Systeme, in den Studien zu Ökosystemdienstleistungen in städtischen Gebieten ignoriert. Die Forschungsziele und Fragestellungen dieser Dissertation lauten: i) Stand der aktuellen Forschung zur dritten Dimension von Ökosystemdienstleistungen im städtischen Raum, ii) Beurteilung des Zusammenhangs von urbanen mehrdimensionalen Indikatoren (zwei- und dreidimensionalen Indikatoren) für die Oberflächentemperatur in der Stadt und iii) Unterschiede zwischen Innen- und Außentemperaturen in urbanen Räumen. Diese Dissertation ist in vier Kapitel gegliedert. Im ersten und zweiten Kapitel werden die Forschungslücken und das Ziel der vorliegenden Untersuchung erläutert. Kapitel 3 enthält die veröffentlichten Artikel. Das letzte Kapitel behandelt die Ergebnisse der veröffentlichten Artikel. Diese Dissertation betont die Bedeutung von dreidimensionalen Studien in urbanen Ökosystemen, um das Konzept der Nachhaltigkeit in Städten voranzutreiben. Deshalb werden kontinentübergreifende Forschungen für weitere Studien empfohlen, die die dreidimensionale Struktur aller städtischen Komponenten und ihre Auswirkungen auf die Außen- und Innentemperatur berücksichtigen. / به جرات می توان گفت که در مطالعات خدمات اکوسیستم، بخصوص خدمات اکوسیستم شهری ، بعد سوم که شامل "ارتفاع و حجم" می باشد اصلا مورد توجه قرار نگرفته است. هدف از این پایان نامه، تلفیق مفهوم بعد سوم در خدمات اکوسیستم شهری و استفاده از فواید آن می باشد. مطالعه بعد سوم دانش ما را در نحوه شکل گیری اقلیم خُرد شهری افزایش می دهد. هدف این پروژه دکتری پاسخ به سوالات ذیل می باشد: 1) سطح آگاهی تحقیقات از بعد سوم خدمات اکوسیستم شهری، 2) ارزیابی ارتباط شاخص های چندبعدی (دو و سه بعدی) با دمای سطح و 3) ارزیابی الگوی دمای درونی و بیرونی در شهر. جهت پاسخ دادن به سوال های مطرح شده، این پژوهش به چهار فصل تقسیم شده است. فصل اول و دوم، که جایگاه خدمات اکوسیستم را در مطالعات شهری بررسی و جای خالی مفهوم بعد سوم در مطالعات خدمات اکوسیستم شهری را جستجو می کند. فصل سوم، شامل سه مقاله چاپ شده در راستای این پروژه دکتری می باشد. فصل چهارم، که نتایج بدست آمده را تجزیه و تحلیل می کند. نتایج بدست آمده نشان می دهد که مطالعات خدمات اکوسیستم شهری از معنی کلی و بنیادی به سمت سازش پذیری شهرها با پدیده تغییر اقلیم در حال تغییر است. همچنین نتایج نشان می دهد که ساختار متفاوت شهری بر شکل گیری الگوی دمای بیرون و داخل ساختمان ها موثر می باشد. استنتاج نتایج بدست آمده از این پایان نامه دو مورد را پیشنهاد می کند. اول، بررسی نقش ساختار های دو بعدی و سه بعدی بر روی دیگر شهر ها و تاثیر آن بر شکل گیری دمای بیرون و درونی ساختمان ها. / Among the studies on ecosystem services undertaken in urban areas, a dimension ‘volume and height’, i.e., the third-dimension of urban environment is largely ignored. More specific, three-dimensional spatial models will increase the knowledge of how complex environment shape the micro-climate in urban environment. The research objectives and questions of this dissertation is: i) the status of the current research addressing the third-dimension of ecosystem services in urban area, ii) assessing the association of urban multi-dimensional (two- and three- dimensional) indicators on urban surface temperature and iii) variation of indoor and outdoor urban temperature pattern. This dissertation is organized into four chapters. The first and second chapter explain the gaps in literature and the aim of this research. Chapter 3 holds the published articles. The last chapter discusses the results of the published articles. This dissertation emphasizes the importance of three-dimensional studies in urban ecosystems to advance the concept of sustainability in cities. Therefore, cross-continental studies that consider the three-dimensional structure of all the urban components and its impact on outdoor and indoor temperature is recommended for future research.
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