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Literatura académica sobre el tema "Clovis points"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 31 de enero de 2023

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Artículos de revistas sobre el tema "Clovis points"

Buchanan, Briggs, Brian Andrews, Michael J. O'Brien y Metin I. Eren. "AN ASSESSMENT OF STONE WEAPON TIP STANDARDIZATION DURING THE CLOVIS–FOLSOM TRANSITION IN THE WESTERN UNITED STATES". American Antiquity 83, n.º 4 (octubre de 2018): 721–34. http://dx.doi.org/10.1017/aaq.2018.53.

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It has long been assumed that Folsom points are more standardized than Clovis points, although an adequate test of this proposition has yet to be undertaken. Here, we address that deficiency by using data from a sample of Folsom and Clovis points recovered from sites across the western United States. We used geometric morphometric techniques to capture point shape and then conducted statistical analyses of variability associated with Clovis and Folsom point bases and blades. Our results demonstrate that Folsom bases and blades are less variable than those on earlier Clovis points, indicating an increase in point standardization during the Early Paleoindian period. In addition, despite published claims to the contrary, Clovis and Folsom point bases are no more variable than blades. Based on these results, we conducted additional analyses to examine the modularity and size of Clovis and Folsom points. The results suggest Clovis points have more integrated base and blade segments than Folsom points. We suggest that several classes of Clovis points—intended for different functions—might have been in use during the Clovis period and that the later Folsom points might have served only as weapon tips, the shape of which were constrained by the fluting process.

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Prasciunas, Mary M. "Mapping Clovis: Projectile Points, Behavior, and Bias". American Antiquity 76, n.º 1 (enero de 2011): 107–26. http://dx.doi.org/10.7183/0002-7316.76.1.107.

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The distribution of Clovis projectile points across North America demonstrates distinct spatial patterning that has the potential to inform on many aspects of the colonization process. However, before accurate inferences regarding prehistoric behavior can be drawn from projectile point distributional databases, it is necessary to account for biases potentially affecting point visibility. Using county-level data for a sample of states from the western and southeastern U.S., this paper demonstrates that Clovis projectile point distribution is significantly related to modern population density, cultivated acreage, intensity of archaeological research, and measures of environmental productivity. Interpreting Clovis projectile point distribution is therefore more complex than frequently assumed.

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Aldenderfer, Mark. "Pre-Clovis projectile points in North America". Science 362, n.º 6413 (25 de octubre de 2018): 415.6–416. http://dx.doi.org/10.1126/science.362.6413.415-f.

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Slade, Alan Michael. "To haft and to hold: Evidence for the hafting of Clovis fluted points". Journal of Lithic Studies 8, n.º 3 (21 de diciembre de 2021): 133–51. http://dx.doi.org/10.2218/jls.3033.

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Clovis fluted points vary considerably in technology and morphology, but also share a set of attributes, the most diagnostic of which are the flute scars, the remnants of the flake removals from the basal region that travelled up towards the tip. Fluting on Clovis and Clovis-like points generally extends no further than a third of the way up the face of the point. Finished points are usually ground smooth along the base and lower edges, suggesting facilitation of the hafting (attachment) to a wooden shaft or handle by way of an ivory or bone socket. The points may have been hafted directly to a main-shaft and used as a thrusting spear during close encounter attacks, or in the hand as knife or butchery tool. Alternatively, an intermediary shaft, or foreshaft may have been used to secure the point. The suggestion of foreshafts being used by Clovis hunters received support after the discovery of bone rods in association with mammoth remains and Clovis points at the type site at Blackwater Draw, New Mexico in 1936. Several other Clovis-aged sites across North America have yielded ivory and beveled rods that have also been associated with foreshafts and the hafting of Clovis points. Scratches that are present on a couple of Clovis points made on varieties of obsidian, have been identified as being “hafting abrasion” evidence, this roughening of the surface would have helped in securing the point into the shaft or socket. In one example from the Hoyt site in Oregon, remains of a “pitch” or hafting adhesive was discovered in the abrasions in the fluted area of the point.

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HAYNES, C. VANCE. "DISTRIBUTION OF CLOVIS POINTS IN ARIZONA AND THE CLOVIS EXPLORATION OF THE STATE, 11,000 B.C." KIVA 76, n.º 3 (marzo de 2011): 343–67. http://dx.doi.org/10.1179/kiv.2011.76.3.004.

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Ragan, Kathryn y Briggs Buchanan. "Assessing Collector Bias". Midcontinental Journal of Archaeology 43, n.º 2 (1 de julio de 2018): 91–111. http://dx.doi.org/10.2307/26599973.

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Abstract Clovis points are found across the contiguous United States as isolated surface finds and as elements of assemblages in surface and subsurface deposits. Despite being scattered over the continent, Clovis points exhibit a remarkable degree of standardization, yet there is still a demonstrable level of variation in their shapes across regions. Including isolated points in regional comparative analyses would significantly increase sample sizes and spatial coverage of these analyses; however, the effects of collector bias—the tendency to collect the most typical and aesthetically pleasing points—are unknown. Here, we examine the shape of a sample of isolated Clovis points from the midcontinent using geometric morphometric techniques. We show that resharpening had little effect on the shape of points and that our sample of isolated points are similar in shape to points from assemblages in the midcontinent. Our findings suggest that isolated points have research potential when collector bias is limited.

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Frison, George C., George M. Zeimens, Spencer R. Pelton, Danny N. Walker, Dennis J. Stanford y Marcel Kornfeld. "FURTHER INSIGHTS INTO PALEOINDIAN USE OF THE POWARS II RED OCHER QUARRY (48PL330), WYOMING". American Antiquity 83, n.º 3 (19 de abril de 2018): 485–504. http://dx.doi.org/10.1017/aaq.2018.11.

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We report major new insights from recent research at the Powars II Paleoindian red ocher quarry (48PL330). We salvaged more than 7,000 artifacts from Powars II between 2014 and 2016 by screening redeposited sediment from the talus slope below the intact portion of the site. Clovis artifacts dominate the diagnostic artifact assemblage, including 53 Clovis points, 33 preforms, and artifacts associated with a previously unrecognized blade core industry. We report the first radiocarbon dates from the site, determined from dating bone tools, which indicate Cody-aged use (ca. >10,000 cal BP). Further, salvage efforts discovered a previously unknown toolstone source from which many of the Clovis artifacts were produced. The Powars II Clovis points most resemble early Paleoindian points from the far Northern Plains and were likely both produced and discarded in the red ocher quarry after hunting, as evidenced by preform production and the presence of impact fractures on many used points. Given these production and discard patterns, Powars II holds some of the best evidence archaeologists currently have for Paleoindian ritualism related to hunting.

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Frison, George C. "Experimental Use of Clovis Weaponry and Tools on African Elephants". American Antiquity 54, n.º 4 (octubre de 1989): 766–84. http://dx.doi.org/10.2307/280681.

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Clovis projectile points and chipped-stone tools have been recovered in a number of archaeological sites in the New World, but these cannot be tested on mammoths, which we know from the archaeological evidence Clovis hunters were able to procure. Extensive culling of elephants in Hwange National Park in Zimbabwe provided the necessary animals to test replicas of Clovis tools and weaponry. The experiments leave little doubt that Clovis projectile points can inflict lethal wounds on African elephants and that simple stone tools will perform the necessary butchering tasks. The physiology of mammoths and elephants is similar enough to make positive statements on the potential of this kind of stone-tool and weaponry assemblage, but we will never be able to compare elephant and mammoth behavior directly.

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Fiedel, Stuart J. y Juliet E. Morrow. "Comment on “Clovis and Western Stemmed: Population Migration and the Meeting of Two Technologies in the Intermountain West” by Charlotte Beck and George T. Jones". American Antiquity 77, n.º 2 (abril de 2012): 376–85. http://dx.doi.org/10.7183/0002-7316.77.2.376.

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AbstractBeck and Jones (2010) assert that Clovis “was not first in the Intermountain West”; Western Stemmed points are older than fluted points; and the stemmed point makers derived from a hypothetical pre-13,000 cal B.P. Pacific Coast migration. A less tendentious review of the data suggests instead that Western Stemmed follows Clovis in this region, as previously inferred by Willig and Aikens.

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Waters, Michael R., Joshua L. Keene, Steven L. Forman, Elton R. Prewitt, David L. Carlson y James E. Wiederhold. "Pre-Clovis projectile points at the Debra L. Friedkin site, Texas—Implications for the Late Pleistocene peopling of the Americas". Science Advances 4, n.º 10 (octubre de 2018): eaat4505. http://dx.doi.org/10.1126/sciadv.aat4505.

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Lanceolate projectile points of the Clovis complex and stemmed projectile points of the Western Stemmed Tradition first appeared in North America by ~13 thousand years (ka) ago. The origin, age, and chronological superposition of these stemmed and lanceolate traditions are unclear. At the Debra L. Friedkin site, Texas, below Folsom and Clovis horizons, we find stemmed projectile points dating from ~13.5 to ~15.5 ka ago, with a triangular lanceolate point form appearing ~14 ka ago. The sequential relationship of stemmed projectile points followed by lanceolate forms suggests that lanceolate points are derived from stemmed forms or that they originated from two separate migrations into the Americas.

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Tesis sobre el tema "Clovis points"

Richard, Andrew Justin. "Clovis and Folsom Functionality Comparison". Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/556853.

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This thesis uses experimental archaeology as a method to discover the functional differences between Clovis and Folsom projectile points filtered through a behavioral ecology paradigm. Porcelain is used as a substitute for tool stone for its consistency and control value. The experiment was devised to find out which technology, Clovis or Folsom, was more functional, had a higher curation rate and contributed to increased group subsistence. Paleoindian tool technology transitions can be seen as indicators for adaptation triggered by environmental conditions and changes in subsistence. Folsom technology, when compared to Clovis technology, was functionally superior in performance, refurbishment and curation. Technological design choices made by Folsom people were engineered toward producing a more functional tool system as a sustainable form of risk management. The Clovis Folsom Breakage Experiment indicates that Folsom tool technology was specifically adapted to bison subsistence based on increased functionality and curation.

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Prasciunas, Mary M. "Clovis first? an analysis of space, time, and technology /". Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594497451&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Werner, Angelia N. "Experimental assessment of proximal-lateral edge grinding on haft damage using replicated Clovis points". Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1492848811526633.

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Giraudot, Simon. "Reconstruction robuste de formes à partir de données imparfaites". Thesis, Nice, 2015. http://www.theses.fr/2015NICE4024/document.

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Au cours des vingt dernières années, de nombreux algorithmes de reconstruction de surface ont été développés. Néanmoins, des données additionnelles telles que les normales orientées sont souvent requises et la robustesse aux données imparfaites est encore un vrai défi. Dans cette thèse, nous traitons de nuages de points non-orientés et imparfaits, et proposons deux nouvelles méthodes gérant deux différents types de surfaces. La première méthode, adaptée au bruit, s'applique aux surfaces lisses et fermées. Elle prend en entrée un nuage de points avec du bruit variable et des données aberrantes, et comporte trois grandes étapes. Premièrement, en supposant que la surface est lisse et de dimension connue, nous calculons une fonction distance adaptée au bruit. Puis nous estimons le signe et l'incertitude de la fonction sur un ensemble de points-sources, en minimisant une énergie quadratique exprimée sur les arêtes d'un graphe uniforme aléatoire. Enfin, nous calculons une fonction implicite signée par une approche dite « random walker » avec des contraintes molles choisies aux points-sources de faible incertitude. La seconde méthode génère des surfaces planaires par morceaux, potentiellement non-variétés, représentées par des maillages triangulaires simples. En faisant croitre des primitives planaires convexes sous une erreur de Hausdorff bornée, nous déduisons à la fois la surface et sa connectivité et générons un complexe simplicial qui représente efficacement les grandes régions planaires, les petits éléments et les bords. La convexité des primitives est essentielle pour la robustesse et l'efficacité de notre approche
Over the last two decades, a high number of reliable algorithms for surface reconstruction from point clouds has been developed. However, they often require additional attributes such as normals or visibility, and robustness to defect-laden data is often achieved through strong assumptions and remains a scientific challenge. In this thesis we focus on defect-laden, unoriented point clouds and contribute two new reconstruction methods designed for two specific classes of output surfaces. The first method is noise-adaptive and specialized to smooth, closed shapes. It takes as input a point cloud with variable noise and outliers, and comprises three main steps. First, we compute a novel noise-adaptive distance function to the inferred shape, which relies on the assumption that this shape is a smooth submanifold of known dimension. Second, we estimate the sign and confidence of the function at a set of seed points, through minimizing a quadratic energy expressed on the edges of a uniform random graph. Third, we compute a signed implicit function through a random walker approach with soft constraints chosen as the most confident seed points. The second method generates piecewise-planar surfaces, possibly non-manifold, represented by low complexity triangle surface meshes. Through multiscale region growing of Hausdorff-error-bounded convex planar primitives, we infer both shape and connectivity of the input and generate a simplicial complex that efficiently captures large flat regions as well as small features and boundaries. Imposing convexity of primitives is shown to be crucial to both the robustness and efficacy of our approach

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Truong, Quoc Hung. "Knowledge-based 3D point clouds processing". Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00977434.

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The modeling of real-world scenes through capturing 3D digital data has proven to be both useful andapplicable in a variety of industrial and surveying applications. Entire scenes are generally capturedby laser scanners and represented by large unorganized point clouds possibly along with additionalphotogrammetric data. A typical challenge in processing such point clouds and data lies in detectingand classifying objects that are present in the scene. In addition to the presence of noise, occlusionsand missing data, such tasks are often hindered by the irregularity of the capturing conditions bothwithin the same dataset and from one data set to another. Given the complexity of the underlyingproblems, recent processing approaches attempt to exploit semantic knowledge for identifying andclassifying objects. In the present thesis, we propose a novel approach that makes use of intelligentknowledge management strategies for processing of 3D point clouds as well as identifying andclassifying objects in digitized scenes. Our approach extends the use of semantic knowledge to allstages of the processing, including the guidance of the individual data-driven processing algorithms.The complete solution consists in a multi-stage iterative concept based on three factors: the modeledknowledge, the package of algorithms, and a classification engine. The goal of the present work isto select and guide algorithms following an adaptive and intelligent strategy for detecting objects inpoint clouds. Experiments with two case studies demonstrate the applicability of our approach. Thestudies were carried out on scans of the waiting area of an airport and along the tracks of a railway.In both cases the goal was to detect and identify objects within a defined area. Results show that ourapproach succeeded in identifying the objects of interest while using various data types

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König, Sören y Stefan Gumhold. "Robust Surface Reconstruction from Point Clouds". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-131561.

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The problem of generating a surface triangulation from a set of points with normal information arises in several mesh processing tasks like surface reconstruction or surface resampling. In this paper we present a surface triangulation approach which is based on local 2d delaunay triangulations in tangent space. Our contribution is the extension of this method to surfaces with sharp corners and creases. We demonstrate the robustness of the method on difficult meshing problems that include nearby sheets, self intersecting non manifold surfaces and noisy point samples.

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Filho, Carlos André Braile Przewodowski. "Feature extraction from 3D point clouds". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-30072018-111718/.

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Computer vision is a research field in which images are the main object of study. One of its category of problems is shape description. Object classification is one important example of applications using shape descriptors. Usually, these processes were performed on 2D images. With the large-scale development of new technologies and the affordable price of equipment that generates 3D images, computer vision has adapted to this new scenario, expanding the classic 2D methods to 3D. However, it is important to highlight that 2D methods are mostly dependent on the variation of illumination and color, while 3D sensors provide depth, structure/3D shape and topological information beyond color. Thus, different methods of shape descriptors and robust attributes extraction were studied, from which new attribute extraction methods have been proposed and described based on 3D data. The results obtained from well known public datasets have demonstrated their efficiency and that they compete with other state-of-the-art methods in this area: the RPHSD (a method proposed in this dissertation), achieved 85:4% of accuracy on the University of Washington RGB-D dataset, being the second best accuracy on this dataset; the COMSD (another proposed method) has achieved 82:3% of accuracy, standing at the seventh position in the rank; and the CNSD (another proposed method) at the ninth position. Also, the RPHSD and COMSD methods have relatively small processing complexity, so they achieve high accuracy with low computing time.
Visão computacional é uma área de pesquisa em que as imagens são o principal objeto de estudo. Um dos problemas abordados é o da descrição de formatos (em inglês, shapes). Classificação de objetos é um importante exemplo de aplicação que usa descritores de shapes. Classicamente, esses processos eram realizados em imagens 2D. Com o desenvolvimento em larga escala de novas tecnologias e o barateamento dos equipamentos que geram imagens 3D, a visão computacional se adaptou para este novo cenário, expandindo os métodos 2D clássicos para 3D. Entretanto, estes métodos são, majoritariamente, dependentes da variação de iluminação e de cor, enquanto os sensores 3D fornecem informações de profundidade, shape 3D e topologia, além da cor. Assim, foram estudados diferentes métodos de classificação de objetos e extração de atributos robustos, onde a partir destes são propostos e descritos novos métodos de extração de atributos a partir de dados 3D. Os resultados obtidos utilizando bases de dados 3D públicas conhecidas demonstraram a eficiência dos métodos propóstos e que os mesmos competem com outros métodos no estado-da-arte: o RPHSD (um dos métodos propostos) atingiu 85:4% de acurácia, sendo a segunda maior acurácia neste banco de dados; o COMSD (outro método proposto) atingiu 82:3% de acurácia, se posicionando na sétima posição do ranking; e o CNSD (outro método proposto) em nono lugar. Além disso, os métodos RPHSD têm uma complexidade de processamento relativamente baixa. Assim, eles atingem uma alta acurácia com um pequeno tempo de processamento.

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König, Sören y Stefan Gumhold. "Robust Surface Reconstruction from Point Clouds". Technische Universität Dresden, 2013. https://tud.qucosa.de/id/qucosa%3A27391.

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Aronsson, Oskar y Julia Nyman. "Boundary Representation Modeling from Point Clouds". Thesis, KTH, Bro- och stålbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278543.

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Inspections of bridges are today performed ocularly by an inspector at arm’s lengths distance to evaluate damages and to assess its current condition. Ocular inspections often require specialized equipment to aid the inspector to reach all parts of the bridge. The current state of practice for bridge inspection is therefore considered to be time-consuming, costly, and a safety hazard for the inspector. The purpose of this thesis has been to develop a method for automated modeling of bridges from point cloud data. Point clouds that have been created through photogrammetry from a collection of images acquired with an Unmanned Aerial Vehicle (UAV). This thesis has been an attempt to contribute to the long-term goal of making bridge inspections more efficient by using UAV technology. Several methods for the identification of structural components in point clouds have been evaluated. Based on this, a method has been developed to identify planar surfaces using the model-fitting method Random Sample Consensus (RANSAC). The developed method consists of a set of algorithms written in the programming language Python. The method utilizes intersection points between planes as well as the k-Nearest-Neighbor (k-NN) concept to identify the vertices of the structural elements. The method has been tested both for simulated point cloud data as well as for real bridges, where the images were acquired with a UAV. The results from the simulated point clouds showed that the vertices were modeled with a mean deviation of 0.13− 0.34 mm compared to the true vertex coordinates. For a point cloud of a rectangular column, the algorithms identified all relevant surfaces and were able to reconstruct it with a deviation of less than 2 % for the width and length. The method was also tested on two point clouds of real bridges. The algorithms were able to identify many of the relevant surfaces, but the complexity of the geometries resulted in inadequately reconstructed models.
Besiktning av broar utförs i dagsläget okulärt av en inspektör som på en armlängds avstånd bedömer skadetillståndet. Okulär besiktning kräver därmed ofta speciell utrustning för att inspektören ska kunna nå samtliga delar av bron. Detta resulterar i att det nuvarande tillvägagångssättet för brobesiktning beaktas som tidkrävande, kostsamt samt riskfyllt för inspektören. Syftet med denna uppsats var att utveckla en metod för att modellera broar på ett automatiserat sätt utifrån punktmolnsdata. Punktmolnen skapades genom fotogrammetri, utifrån en samling bilder tagna med en drönare. Uppsatsen har varit en insats för att bidra till det långsiktiga målet att effektivisera brobesiktning genom drönarteknik. Flera metoder för att identifiera konstruktionselement i punktmoln har undersökts. Baserat på detta har en metod utvecklats som identifierar plana ytor med regressionsmetoden Random Sample Consensus (RANSAC). Den utvecklade metoden består av en samling algoritmer skrivna i programmeringsspråket Python. Metoden grundar sig i att beräkna skärningspunkter mellan plan samt använder konceptet k-Nearest-Neighbor (k-NN) för att identifiera konstruktionselementens hörnpunkter. Metoden har testats på både simulerade punktmolnsdata och på punktmoln av fysiska broar, där bildinsamling har skett med hjälp av en drönare. Resultatet från de simulerade punktmolnen visade att hörnpunkterna kunde identifieras med en medelavvikelse på 0,13 − 0,34 mm jämfört med de faktiska hörnpunkterna. För ett punktmoln av en rektangulär pelare lyckades algoritmerna identifiera alla relevanta ytor och skapa en rekonstruerad modell med en avvikelse på mindre än 2 % med avseende på dess bredd och längd. Metoden testades även på två punktmoln av riktiga broar. Algoritmerna lyckades identifiera många av de relevanta ytorna, men geometriernas komplexitet resulterade i bristfälligt rekonstruerade modeller.

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Otepka, Johannes, Sajid Ghuffar, Christoph Waldhauser, Ronald Hochreiter y Norbert Pfeifer. "Georeferenced Point Clouds: A Survey of Features and Point Cloud Management". MDPI AG, 2013. http://dx.doi.org/10.3390/ijgi2041038.

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This paper presents a survey of georeferenced point clouds. Concentration is, on the one hand, put on features, which originate in the measurement process themselves, and features derived by processing the point cloud. On the other hand, approaches for the processing of georeferenced point clouds are reviewed. This includes the data structures, but also spatial processing concepts. We suggest a categorization of features into levels that reflect the amount of processing. Point clouds are found across many disciplines, which is reflected in the versatility of the literature suggesting specific features. (authors' abstract)

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Libros sobre el tema "Clovis points"

Callahan, Errett. The basics of biface knapping in the eastern fluted point tradition: A manual for flintknapers and lithic analysts. [United States]: Eastern States Archeological Federation, 1990.

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Sanders, Thomas N. Adams: The manufacturing of flaked stone tools at a paleoindian site in western Kentucky. Buffalo, N.Y: Persimmon Press, 1990.

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Jennings, Thomas A. (Thomas Andrew), 1979- author, ed. The Hogeye Clovis cache. College Station: Texas A&M University Press, 2015.

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Ferring, C. Reid. The archaeology and paleoecology of the Aubrey Clovis site (41DN479) Denton County, Texas. [Fort Worth, Tex.]: U.S. Army Corps of Engineers, Fort Worth District, 2001.

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Jennings, Thomas A. y Ashley M. Smallwood. Clovis: On the edge of a new understanding. College Station: Texas A&M University Press, 2014.

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McAvoy, Joseph M. Nottoway River survey: The 30 year study of a late ice age hunting culture on the southern interior coastal plain of Virginia. Courtland, Va: Archeological Society of Virginia, 1992.

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Haynes, Gary. The early settlement of North America: The Clovis era. New York: Cambridge University Press, 2002.

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Collins, Michael B. Clovis blade technology: A comparative study of the Keven Davis Cache, Texas. Austin: University of Texas Press, 1999.

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Jack, Hranicky Wm. Bipoints before Clovis: Trans-oceanic migrations and settlement of prehistoric Americas. Boca Raton: Universal Publishers, 2012.

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D, Pevny Charlotte y Carlson David Lee 1952-, eds. Clovis technology at the Gault Site in Texas: Investigation of a stratified lithic workshop. College Station: Texas A&M University Press, 2011.

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Capítulos de libros sobre el tema "Clovis points"

Dincauze, Dena F. "Fluted Points in the Eastern Forests". En From Kostenki to Clovis, 279–92. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4899-1112-4_20.

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Morrow, Juliet E. y Toby A. Morrow. "Exploring the Clovis-Gainey-Folsom Continuum: Technological and Morphological Variation in Midwestern Fluted Points". En Folsom Technology and Lifeways, 141–57. New York: Routledge, 2021. http://dx.doi.org/10.4324/9781315428338-9.

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Phan, Anh Thu Thi, Quoc Thai Phan y Anh Khoa Viet Nguyen. "Extracting Ground Points and Generating Digital Elevation Model (DEM) from Point Clouds from Point Clouds". En Lecture Notes in Civil Engineering, 589–96. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-3303-5_52.

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Niwiński, Damian. "On fixed-point clones". En Automata, Languages and Programming, 464–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/3-540-16761-7_96.

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Kramer, Jeff, Nicolas Burrus, Florian Echtler, Herrera C. Daniel y Matt Parker. "Point Clouds, Part 1". En Hacking the Kinect, 127–50. Berkeley, CA: Apress, 2012. http://dx.doi.org/10.1007/978-1-4302-3868-3_7.

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Kramer, Jeff, Nicolas Burrus, Florian Echtler, Herrera C. Daniel y Matt Parker. "Point Clouds, Part 2". En Hacking the Kinect, 151–72. Berkeley, CA: Apress, 2012. http://dx.doi.org/10.1007/978-1-4302-3868-3_8.

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Silván-Cárdenas, José Luis. "A Multiscale Erosion Operator for Discriminating Ground Points in LiDAR Point Clouds". En Lecture Notes in Computer Science, 213–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-38989-4_22.

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Kermarrec, Gaël, Vibeke Skytt y Tor Dokken. "LR B-Splines for Representation of Terrain and Seabed: Data Fusion, Outliers, and Voids". En Optimal Surface Fitting of Point Clouds Using Local Refinement, 57–80. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-16954-0_5.

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AbstractPerforming surface approximation of geospatial point clouds with locally refined (LR) B-splines comes with several challenges: (i) Point clouds have varying data density, (ii) outliers should be eliminated without deleting features, (iii) voids, also called holes, or data gaps should be treated specifically to avoid the drop of the approximated surface in domains without points. These factors tend to be even more challenging when point clouds acquired from different sensors having different noise characteristics are fused together. The data set becomes non-uniform and the fusing process itself involves a risk of an increased noise level. In this chapter, we provide some tools to answer those specific challenges. We will use terrain and seabed data and show didactically how to perform adaptive surface approximation with local refinement and to select customized parameters. We will further address the problem of choosing an appropriate tolerance for performing an adaptive fitting, and discuss the refinement strategies within the context of LR B-splines. The latter is shown to provide a promising framework for surface fitting of heterogeneous point clouds from various sources.

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Chen, Yunlu, Vincent Tao Hu, Efstratios Gavves, Thomas Mensink, Pascal Mettes, Pengwan Yang y Cees G. M. Snoek. "PointMixup: Augmentation for Point Clouds". En Computer Vision – ECCV 2020, 330–45. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58580-8_20.

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Toll, Bill y Fuhua Cheng. "Surface Reconstruction from Point Clouds". En Machining Impossible Shapes, 173–78. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-0-387-35392-0_18.

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Actas de conferencias sobre el tema "Clovis points"

Men, Hao y Kishore Pochiraju. "Hue Assisted Registration of 3D Point Clouds". En ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-29192.

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This paper presents a variant of the Iterative Closest Point (ICP) algorithm for merging multiple color point clouds generated from a mobile 3D Light Detection and Ranging (LIDAR) System. This algorithm uses hue information generated from a camera along with the coordinates of the scan points and enables high accuracy registration of point clouds. A k-d tree based nearest neighbor search associates corresponding colored points in 4-D space between data and model point clouds. Singular Value Decomposition (SVD) method solves for the rigid rotation and translation. Experimental results illustrate that 3D color point clouds accelerate the 3D map registration if the hue data and model point clouds have sufficient hue distribution and the imaging sensor robustly captures the hue.

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Ahmed, Mirza Tahir, Mustafa Mohamad, Joshua A. Marshall y Michael Greenspan. "Registration of Noisy Point Clouds Using Virtual Interest Points". En 2015 12th Conference on Computer and Robot Vision (CRV). IEEE, 2015. http://dx.doi.org/10.1109/crv.2015.12.

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Kim, Sunghan, Mingyu Kim, Jeongtae Lee, Jinhwi Pyo, Heeyoung Heo, Dongho Yun y Kwanghee Ko. "Registration of 3D Point Clouds for Ship Block Measurement". En SNAME 5th World Maritime Technology Conference. SNAME, 2015. http://dx.doi.org/10.5957/wmtc-2015-252.

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In this paper, a software system for registration of point clouds is developed. The system consists of two modules for registration and user interaction. The registration module contains functions for manual and automatic registration. The manual method allows a user to select feature points or planes from the point clouds manually. The selected planes or features are then processed to establish the correspondence between the point clouds, and registration is performed to obtain one large point cloud. The automatic registration uses sphere targets. Sphere targets are attached to an object of interest. A scanner measures the object as well as the targets to produce point clouds, from which the targets are extracted using shape intrinsic properties. Then correspondence between the point clouds is obtained using the targets, and the registration is performed. The user interaction module provides a GUI environment which allows a user to navigate point clouds, to compute various features, to visualize point clouds and to select/unselect points interactively and the point-processing unit containing functions for filtering, estimation of geometric features, and various data structures for managing point clouds of large size. The developed system is tested with actual measurement data of various blocks in a shipyard.

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Okamoto, Hiroki y Hiroshi Masuda. "A Point-Based Virtual Reality System for Supporting Product Development". En ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59756.

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In this paper, we discuss methods to efficiently render stereoscopic scenes of large-scale point-clouds on inexpensive VR systems. Recently, terrestrial laser scanners are significantly improved, and they can easily capture tens of millions points in a short time from large fields, such as engineering plants. If 3D stereoscopic scenes of large-scale point-clouds could be easily rendered using inexpensive devices, they might be involved in casual product development phases. However, it is difficult to render a huge number of points using common PCs, because VR systems require high frame rates to avoid VR sickness. To solve this problem, we introduce an efficient culling method for large-scale point-clouds. In our method, we project all points onto angle-space panoramic images, whose axes are the azimuth and elevation angles of head directions. Then we eliminate occluded and redundant points according to the resolutions of devices. Once visible points are selected, they can be rendered in high frame rates. Visible points are updated when the user stays at a certain position to observe target objects. Since points are processed on image space in our method, preprocessing is very fast. In our experiments, our method could render stereoscopic views of large-scale point-clouds in high frame rates.

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Qingda, Guo y Quan Yanming. "Coarse registration of dense point clouds based on image feature points". En 2020 4th Annual International Conference on Data Science and Business Analytics (ICDSBA). IEEE, 2020. http://dx.doi.org/10.1109/icdsba51020.2020.00078.

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Midorikawa, Yoshitaka y Hiroshi Masuda. "Extraction of Surfaces Using Section Curves for Engineering Plants". En ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85359.

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For simulating renovation of industrial facilities, 3D models are very useful. However, it is time-consuming to create 3D models. The terrestrial laser scanner is effective for easily capturing 3D data of large-scale facilities. So far, many researchers have proposed methods for reconstructing pipe structures in industrial plants using point-clouds. In those methods, planes and cylinders are extracted from point-clouds, but they are not enough for creating various types of equipment. Especially, in manufacturing plants for liquids and gases, rotating surfaces and generalized cylinders are typically used as well as planes and cylinders. In this paper, this paper proposes methods for extracting rotating surfaces and generalized cylinders from noisy and incomplete point-clouds. Since the section shapes of rotating surfaces and generalized cylinders are approximately ellipses, this method detects elliptic section shapes from point-clouds. Then rotating surfaces and generalized cylinders are reconstructed by extracting the center curves and section circles. Then the authors combine this method with general-purpose voxel-based shape reconstruction methods. Since this method is robust to missing points caused by occlusion, the quality of shape reconstruction can be improved even if points are partly missing due to occlusion.

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Yazdi, Seyed Kamaleddin Mostafavi, Farzam Farahmand y Ali Jafari. "Tracking the 3D Configuration of Human Joint Using an MR Image Registration Technique". En ASME 2010 5th Frontiers in Biomedical Devices Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/biomed2010-32057.

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Surface registration is a necessary step and widely used in medical image-aided surgery. It’s relevance to medical imaging is that there is much useful anatomical information in the form of collected surface points which originate from complimentary modalities. In this study, the kinematic relations between two point clouds with different coordinate definitions have been generated. Using Influence Method of surface modeling for extracting point clouds functions, the transformation matrix would be resulted. The proposed method was applied for an experimental femur data points (651 points) using the MRI images. These data points were transformed in a 30 degrees flexion of knee. This transformation contains [0,−9.5, 1] degrees for yaw, pitch and roll rotation and [−3, 14,−13] translation. The related results shows [0, 9.3, 0.95] degrees for rotation and [−2.85, 14.11,−13.07] translation.

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Zhang, Yifan, Qingyong Hu, Guoquan Xu, Yanxin Ma, Jianwei Wan y Yulan Guo. "Not All Points Are Equal: Learning Highly Efficient Point-based Detectors for 3D LiDAR Point Clouds". En 2022 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR). IEEE, 2022. http://dx.doi.org/10.1109/cvpr52688.2022.01838.

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Dey, T. K., G. Li y J. Sun. "Normal estimation for point clouds: a comparison study for a Voronoi based method". En Point-Based Graphics 2005. IEEE, 2005. http://dx.doi.org/10.1109/pbg.2005.194062.

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Limberger, Frederico y Manuel Oliveira. "Real-Time Detection of Planar Regions in Unorganized Point Clouds". En XXVIII Concurso de Teses e Dissertações da SBC. Sociedade Brasileira de Computação - SBC, 2020. http://dx.doi.org/10.5753/ctd.2015.10000.

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Automatic detection of planar regions in point clouds is an important step for many graphics, image processing, and computer vision applications. While laser scanners and digital photography have allowed us to capture increasingly larger datasets, previous approaches for planar region detection are computationally expensive, precluding their use in real-time applications. We present an O(n log n) technique for plane detection in unorganized point clouds based on an efficient Hough-transform voting scheme. It works by clustering sets of approximately co-planar points and by casting votes for these clusters on a spherical accumulator using a trivariate Gaussian kernel. A comparison with competing techniques shows that our approach is considerably faster and scales significantly better than previous ones, being the first practical solution for deterministic plane detection in large unorganized point clouds.

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Informes sobre el tema "Clovis points"

Witzgall, Christoph y Geraldine S. Cheok. Registering 3D point clouds:. Gaithersburg, MD: National Institute of Standards and Technology, 2001. http://dx.doi.org/10.6028/nist.ir.6743.

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Memoli, Facundo y Guillermo Sapiro. Distance Functions and Geodesics on Points Clouds. Fort Belvoir, VA: Defense Technical Information Center, enero de 2005. http://dx.doi.org/10.21236/ada437158.

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Berney, Ernest, Naveen Ganesh, Andrew Ward, J. Newman y John Rushing. Methodology for remote assessment of pavement distresses from point cloud analysis. Engineer Research and Development Center (U.S.), abril de 2021. http://dx.doi.org/10.21079/11681/40401.

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The ability to remotely assess road and airfield pavement condition is critical to dynamic basing, contingency deployment, convoy entry and sustainment, and post-attack reconnaissance. Current Army processes to evaluate surface condition are time-consuming and require Soldier presence. Recent developments in the area of photogrammetry and light detection and ranging (LiDAR) enable rapid generation of three-dimensional point cloud models of the pavement surface. Point clouds were generated from data collected on a series of asphalt, concrete, and unsurfaced pavements using ground- and aerial-based sensors. ERDC-developed algorithms automatically discretize the pavement surface into cross- and grid-based sections to identify physical surface distresses such as depressions, ruts, and cracks. Depressions can be sized from the point-to-point distances bounding each depression, and surface roughness is determined based on the point heights along a given cross section. Noted distresses are exported to a distress map file containing only the distress points and their locations for later visualization and quality control along with classification and quantification. Further research and automation into point cloud analysis is ongoing with the goal of enabling Soldiers with limited training the capability to rapidly assess pavement surface condition from a remote platform.

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Berney, Ernest, Andrew Ward y Naveen Ganesh. First generation automated assessment of airfield damage using LiDAR point clouds. Engineer Research and Development Center (U.S.), marzo de 2021. http://dx.doi.org/10.21079/11681/40042.

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This research developed an automated software technique for identifying type, size, and location of man-made airfield damage including craters, spalls, and camouflets from a digitized three-dimensional point cloud of the airfield surface. Point clouds were initially generated from Light Detection and Ranging (LiDAR) sensors mounted on elevated lifts to simulate aerial data collection and, later, an actual unmanned aerial system. LiDAR data provided a high-resolution, globally positioned, and dimensionally scaled point cloud exported in a LAS file format that was automatically retrieved and processed using volumetric detection algorithms developed in the MATLAB software environment. Developed MATLAB algorithms used a three-stage filling technique to identify the boundaries of craters first, then spalls, then camouflets, and scaled their sizes based on the greatest pointwise extents. All pavement damages and their locations were saved as shapefiles and uploaded into the GeoExPT processing environment for visualization and quality control. This technique requires no user input between data collection and GeoExPT visualization, allowing for a completely automated software analysis with all filters and data processing hidden from the user.

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Sabo, N., A. Beaulieu, D. Bélanger, Y. Belzile y B. Piché. The GeoHashTree: a multi-resolution data structure for the management of point clouds. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2014. http://dx.doi.org/10.4095/293383.

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Haro, Gloria, Gregory Randall y Guillermo Sapiro. Stratification Learning: Detecting Mixed Density and Dimensionality in High Dimensional Point Clouds (PREPRINT). Fort Belvoir, VA: Defense Technical Information Center, septiembre de 2006. http://dx.doi.org/10.21236/ada478351.

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Boike, J., J. Hartmann, S. Lange, B. Hartig y V. Helm. Airborne laser scanning (ALS) point clouds of Trail Valley Creek and Inuvik-Tuktoyaktuk Highway (ITH). Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2019. http://dx.doi.org/10.4095/321051.

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Habib, Ayman, Darcy M. Bullock, Yi-Chun Lin y Raja Manish. Road Ditch Line Mapping with Mobile LiDAR. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317354.

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Maintenance of roadside ditches is important to avoid localized flooding and premature failure of pavements. Scheduling effective preventative maintenance requires mapping of the ditch profile to identify areas requiring excavation of long-term sediment accumulation. High-resolution, high-quality point clouds collected by mobile LiDAR mapping systems (MLMS) provide an opportunity for effective monitoring of roadside ditches and performing hydrological analyses. This study evaluated the applicability of mobile LiDAR for mapping roadside ditches for slope and drainage analyses. The performance of alternative MLMS units was performed. These MLMS included an unmanned ground vehicle, an unmanned aerial vehicle, a portable backpack system along with its vehicle-mounted version, a medium-grade wheel-based system, and a high-grade wheel-based system. Point cloud from all the MLMS units were in agreement in the vertical direction within the ±3 cm range for solid surfaces, such as paved roads, and ±7 cm range for surfaces with vegetation. The portable backpack system that could be carried by a surveyor or mounted on a vehicle and was the most flexible MLMS. The report concludes that due to flexibility and cost effectiveness of the portable backpack system, it is the preferred platform for mapping roadside ditches, followed by the medium-grade wheel-based system. Furthermore, a framework for ditch line characterization is proposed and tested using datasets acquired by the medium-grade wheel-based and vehicle-mounted portable systems over a state highway. An existing ground filtering approach is modified to handle variations in point density of mobile LiDAR data. Hydrological analyses, including flow direction and flow accumulation, are applied to extract the drainage network from the digital terrain model (DTM). Cross-sectional/longitudinal profiles of the ditch are automatically extracted from LiDAR data and visualized in 3D point clouds and 2D images. The slope derived from the LiDAR data was found to be very close to highway cross slope design standards of 2% on driving lanes, 4% on shoulders, as well as 6-by-1 slope for ditch lines. Potential flooded regions are identified by detecting areas with no LiDAR return and a recall score of 54% and 92% was achieved by the medium-grade wheel-based and vehicle-mounted portable systems, respectively. Furthermore, a framework for ditch line characterization is proposed and tested using datasets acquired by the medium-grade wheel-based and vehicle-mounted portable systems over a state highway. An existing ground filtering approach is modified to handle variations in point density of mobile LiDAR data. Hydrological analyses, including flow direction and flow accumulation, are applied to extract the drainage network from the digital terrain model (DTM). Cross-sectional/longitudinal profiles of the ditch are automatically extracted from LiDAR data, and visualized in 3D point clouds and 2D images. The slope derived from the LiDAR data was found to be very close to highway cross slope design standards of 2% on driving lanes, 4% on shoulder, as well as 6-by-1 slope for ditch lines. Potential flooded regions are identified by detecting areas with no LiDAR return and a recall score of 54% and 92% was achieved by the medium-grade wheel-based and vehicle-mounted portable systems, respectively.

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Caetano, Gerardo. Analysis and foresight of the European Union - Mercosur Association Agreement. Fundación Carolina, abril de 2022. http://dx.doi.org/10.33960/issn-e.1885-9119.dtff04en.

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After a negotiation that has been ongoing for more than two decades, the “agreement in principle” between the European Union and Mercosur regarding the trade pillar, announced in June 2019, has not been confirmed. Moreover, in the current context, the perspectives that are outlined in both blocks are not auspicious, for various reasons that are analyzed. In this context, the text will analyzes the following points: i) in the absence of a specific Treaty in progress of application, it informs about the negotiations of the trade pillar, its current status, the contents of the principle of agreement signed in 2019, the possibilities of closure and ratification by the two parties and the main expected impacts; ii) the potential implications of this agreement for both the European Union and Mercosur, in particular with regard to its foreseeable consequences for the strategic autonomy of both regions and for the strengthening of multilateralism at present; and iii) the expected impacts of the COVID-19 pandemic and the eventual contribution of this Association Agreement in the new scenarios. The text closes with a brief overview.

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Snyder, Victor A., Dani Or, Amos Hadas y S. Assouline. Characterization of Post-Tillage Soil Fragmentation and Rejoining Affecting Soil Pore Space Evolution and Transport Properties. United States Department of Agriculture, abril de 2002. http://dx.doi.org/10.32747/2002.7580670.bard.

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Tillage modifies soil structure, altering conditions for plant growth and transport processes through the soil. However, the resulting loose structure is unstable and susceptible to collapse due to aggregate fragmentation during wetting and drying cycles, and coalescense of moist aggregates by internal capillary forces and external compactive stresses. Presently, limited understanding of these complex processes often leads to consideration of the soil plow layer as a static porous medium. With the purpose of filling some of this knowledge gap, the objectives of this Project were to: 1) Identify and quantify the major factors causing breakdown of primary soil fragments produced by tillage into smaller secondary fragments; 2) Identify and quantify the. physical processes involved in the coalescence of primary and secondary fragments and surfaces of weakness; 3) Measure temporal changes in pore-size distributions and hydraulic properties of reconstructed aggregate beds as a function of specified initial conditions and wetting/drying events; and 4) Construct a process-based model of post-tillage changes in soil structural and hydraulic properties of the plow layer and validate it against field experiments. A dynamic theory of capillary-driven plastic deformation of adjoining aggregates was developed, where instantaneous rate of change in geometry of aggregates and inter-aggregate pores was related to current geometry of the solid-gas-liquid system and measured soil rheological functions. The theory and supporting data showed that consolidation of aggregate beds is largely an event-driven process, restricted to a fairly narrow range of soil water contents where capillary suction is great enough to generate coalescence but where soil mechanical strength is still low enough to allow plastic deforn1ation of aggregates. The theory was also used to explain effects of transient external loading on compaction of aggregate beds. A stochastic forInalism was developed for modeling soil pore space evolution, based on the Fokker Planck equation (FPE). Analytical solutions for the FPE were developed, with parameters which can be measured empirically or related to the mechanistic aggregate deformation model. Pre-existing results from field experiments were used to illustrate how the FPE formalism can be applied to field data. Fragmentation of soil clods after tillage was observed to be an event-driven (as opposed to continuous) process that occurred only during wetting, and only as clods approached the saturation point. The major mechanism of fragmentation of large aggregates seemed to be differential soil swelling behind the wetting front. Aggregate "explosion" due to air entrapment seemed limited to small aggregates wetted simultaneously over their entire surface. Breakdown of large aggregates from 11 clay soils during successive wetting and drying cycles produced fragment size distributions which differed primarily by a scale factor l (essentially equivalent to the Van Bavel mean weight diameter), so that evolution of fragment size distributions could be modeled in terms of changes in l. For a given number of wetting and drying cycles, l decreased systematically with increasing plasticity index. When air-dry soil clods were slightly weakened by a single wetting event, and then allowed to "age" for six weeks at constant high water content, drop-shatter resistance in aged relative to non-aged clods was found to increase in proportion to plasticity index. This seemed consistent with the rheological model, which predicts faster plastic coalescence around small voids and sharp cracks (with resulting soil strengthening) in soils with low resistance to plastic yield and flow. A new theory of crack growth in "idealized" elastoplastic materials was formulated, with potential application to soil fracture phenomena. The theory was preliminarily (and successfully) tested using carbon steel, a ductile material which closely approximates ideal elastoplastic behavior, and for which the necessary fracture data existed in the literature.

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