Calculation of wood volume and stem taper using terrestrial single-image close-range photogrammetry and contemporary software tools

Abstract

The use of close-range photogrammetry in zooarchaeology : Creating accurate 3D models of wolf crania to study dog domestication

Acknowledgements We thank the Muséum National d'Histoire Naturelle, Paris, that provided access to the specimens, and access to the morphometric platform where the surface scans were performed. We also thank Raphael Cornette and Julien Claude for the fruitful discussions we had when writing the manuscript. This work was supported by NERC (grant number NE/K003259/1) and the European Research Council (ERC-2013-StG 337574-UNDEAD). This is publication ISEM 2016-127. We thank the two anonymous reviewers who greatly helped to improve the manuscript.

Accuracy assessment of a photogrammetric close-range reconstruction system

Geometric accuracy of a close-range photogrammetric system is assessed in this paper considering surface reconstruction with structured light as its main purpose. The system is based on an off-the-shelf digital camera and a pattern projector. The mathematical model for reconstruction is based on the parametric equation of the projected straight line combined with collinearity equations. A sequential approach for system calibration was developed and is presented. Results obtained from real data are also presented and discussed. Experiments with real data using a prototype have indicated 0.5mm of accuracy in height determination and 0.2mm in the XY plane considering an application where the object was 1630mm distant from the camera.

Fluvio-morphological processes of meander bends - Combining conventional field measurements, close-range remote sensing and computational modelling

Meandering rivers have been perceived to evolve rather similarly around the world independently of the location or size of the river. Despite the many consistent processes and characteristics they have also been noted to show complex and unique sets of fluviomorphological processes in which local factors play important role. These complex interactions of flow and morphology affect notably the development of the river. Comprehensive and fundamental field, flume and theoretically based studies of fluviomorphological processes in meandering rivers have been carried out especially during the latter part of the 20th century. However, as these studies have been carried out with traditional field measurements techniques their spatial and temporal resolution is not competitive to the level achievable today. The hypothesis of this study is that, by exploiting e increased spatial and temporal resolution of the data, achieved by combining conventional field measurements with a range of modern technologies, will provide new insights to the spatial patterns of the flow-sediment interaction in meandering streams, which have perceived to show notable variation in space and time. This thesis shows how the modern technologies can be combined to derive very high spatial and temporal resolution data on fluvio-morphological processes over meander bends. The flow structure over the bends is recorded in situ using acoustic Doppler current profiler (ADCP) and the spatial and temporal resolution of the flow data is enhanced using 2D and 3D CFD over various meander bends. The CFD are also exploited to simulate sediment transport. Multi-temporal terrestrial laser scanning (TLS), mobile laser scanning (MLS) and echo sounding data are used to measure the flow-based changes and formations over meander bends and to build the computational models. The spatial patterns of erosion and deposition over meander bends are analysed relative to the measured and modelled flow field and sediment transport. The results are compared with the classic theories of the processes in meander bends. Mainly, the results of this study follow well the existing theories and results of previous studies. However, some new insights regarding to the spatial and temporal patterns of the flow-sediment interaction in a natural sand-bed meander bend are provided. The results of this study show the advantages of the rapid and detailed measurements techniques and the achieved spatial and temporal resolution provided by CFD, unachievable with field measurements. The thesis also discusses the limitations which remain in the measurement and modelling methods and in understanding of fluvial geomorphology of meander bends. Further, the hydro- and morphodynamic models’ sensitivity to user-defined parameters is tested, and the modelling results are assessed against detailed field measurement. The study is implemented in the meandering sub-Arctic Pulmanki River in Finland. The river is unregulated and sand-bed and major morphological changes occur annually on the meander point bars, which are inundated only during the snow-melt-induced spring floods. The outcome of this study applies to sandbed meandering rivers in regions where normally one significant flood event occurs annually, such as Arctic areas with snow-melt induced spring floods, and where the point bars of the meander bends are inundated only during the flood events.

A simple and effective air shotgun for collecting small birds and other vertebrates at close range

Scientific collections are important sources of material for many areas of ornithological research. Although firearms (particularly shotguns) have been the standard for avian scientific collecting for more than 100 years, their use is restricted in many areas of the world. We describe a cheap, relatively silent, and effective air shotgun for collecting birds weighing up to 50 g at distances up to 4 m. This air shotgun is capable of shooting birdshot, uses hollow metal rivets connected to plastic straws as shot shells, and represents a simple adaptation of any 0.177 or 0.22 cal single-shot, break-barrel air rifle with at least 25 joules of muzzle energy. This air shotgun will be especially useful for focused sampling of birds (and other small vertebrates) in situations where firearm use or transport is restricted.

Zone policeman 88; a close range study of the Panama canal and its workers,

London edition (T. F. Unwin) has title: Things as they are in Panama.

At close range,

Mode of access: Internet.

Whittier at close range,

Mode of access: Internet.

Optimization of Snow Drifting Mitigation and Control Methods for Iowa Conditions Part II, TR-626, 2015

Blowing and drifting of snow is a major concern for transportation efficiency and road safety in regions where their development is common. One common way to mitigate snow drift on roadways is to install plastic snow fences. Correct design of snow fences is critical for road safety and maintaining the roads open during winter in the US Midwest and other states affected by large snow events during the winter season and to maintain costs related to accumulation of snow on the roads and repair of roads to minimum levels. Of critical importance for road safety is the protection against snow drifting in regions with narrow rights of way, where standard fences cannot be deployed at the recommended distance from the road. Designing snow fences requires sound engineering judgment and a thorough evaluation of the potential for snow blowing and drifting at the construction site. The evaluation includes site-specific design parameters typically obtained with semi-empirical relations characterizing the local transport conditions. Among the critical parameters involved in fence design and assessment of their post-construction efficiency is the quantification of the snow accumulation at fence sites. The present study proposes a joint experimental and numerical approach to monitor snow deposits around snow fences, quantitatively estimate snow deposits in the field, asses the efficiency and improve the design of snow fences. Snow deposit profiles were mapped using GPS based real-time kinematic surveys (RTK) conducted at the monitored field site during and after snow storms. The monitored site allowed testing different snow fence designs under close to identical conditions over four winter seasons. The study also discusses the detailed monitoring system and analysis of weather forecast and meteorological conditions at the monitored sites. A main goal of the present study was to assess the performance of lightweight plastic snow fences with a lower porosity than the typical 50% porosity used in standard designs of such fences. The field data collected during the first winter was used to identify the best design for snow fences with a porosity of 50%. Flow fields obtained from numerical simulations showed that the fence design that worked the best during the first winter induced the formation of an elongated area of small velocity magnitude close to the ground. This information was used to identify other candidates for optimum design of fences with a lower porosity. Two of the designs with a fence porosity of 30% that were found to perform well based on results of numerical simulations were tested in the field during the second winter along with the best performing design for fences with a porosity of 50%. Field data showed that the length of the snow deposit away from the fence was reduced by about 30% for the two proposed lower-porosity (30%) fence designs compared to the best design identified for fences with a porosity of 50%. Moreover, one of the lower-porosity designs tested in the field showed no significant snow deposition within the bottom gap region beneath the fence. Thus, a major outcome of this study is to recommend using plastic snow fences with a porosity of 30%. It is expected that this lower-porosity design will continue to work well for even more severe snow events or for successive snow events occurring during the same winter. The approach advocated in the present study allowed making general recommendations for optimizing the design of lower-porosity plastic snow fences. This approach can be extended to improve the design of other types of snow fences. Some preliminary work for living snow fences is also discussed. Another major contribution of this study is to propose, develop protocols and test a novel technique based on close range photogrammetry (CRP) to quantify the snow deposits trapped snow fences. As image data can be acquired continuously, the time evolution of the volume of snow retained by a snow fence during a storm or during a whole winter season can, in principle, be obtained. Moreover, CRP is a non-intrusive method that eliminates the need to perform man-made measurements during the storms, which are difficult and sometimes dangerous to perform. Presently, there is lots of empiricism in the design of snow fences due to lack of data on fence storage capacity on how snow deposits change with the fence design and snow storm characteristics and in the estimation of the main parameters used by the state DOTs to design snow fences at a given site. The availability of such information from CRP measurements should provide critical data for the evaluation of the performance of a certain snow fence design that is tested by the IDOT. As part of the present study, the novel CRP method is tested at several sites. The present study also discusses some attempts and preliminary work to determine the snow relocation coefficient which is one of the main variables that has to be estimated by IDOT engineers when using the standard snow fence design software (Snow Drift Profiler, Tabler, 2006). Our analysis showed that standard empirical formulas did not produce reasonable values when applied at the Iowa test sites monitored as part of the present study and that simple methods to estimate this variable are not reliable. The present study makes recommendations for the development of a new methodology based on Large Scale Particle Image Velocimetry that can directly measure the snow drift fluxes and the amount of snow relocated by the fence.

A low-cost 3D reconstruction system using a single-shot projection of a pattern matrix

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo de métodos para classificação e localização precisa de padrões usando um sistema de luz estruturada

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelagem fotogramétrica e calibração de um sistema de visão omnidirecional

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lateral spreading and associated slope processes in fractured rock slabs

Landslides of the lateral spreading type, involving brittle geological units overlying ductile terrains, are a common occurrence in the sandstone and limestone plateaux of the northern Apennines of Italy. These instability phenomena can become particularly risky, when historical towns and cultural heritage sites built on the top of them are endangered. Neverthless, the mechanisms controlling the developing of related instabilities, i.e. toppling and rock falls, at the edges of rock plateaux are not fully understood yet. In addition, the groundwater flow path developing at the contact between the more permeable units, i.e. the jointed rock slab, and the relatively impermeable clay-rich units have not been already studied in details, even if they may play a role in this kind of instability processes, acting as eventual predisposing and/or triggering factors. Field survey, Terrestrial Laser Scanner and Close Range Photogrammetry techniques, laboratory tests on the involved materials, hydrogeological monitoring and modelling, displacements evaluation and stability analysis through continuum and discontinuum numerical codes have been performed on the San Leo case study, with the aim to bring further insights for the understanding and the assessment of the slope processes taking place in this geological context. The current research permitted to relate the aquifer behaviour of the rocky slab to slope instability processes. The aquifer hosted in the fractured slab leads to the development of perennial and ephemeral springs at the contact between the two units. The related piping erosion phenomena, together with slope processes in the clay-shales led to the progressive undermining of the slab. The cliff becomes progressively unstable due to undermining and undergoes large-scale landslides due to fall or topple.

Assessment of Underground Wine Cellars Using Geographic Information Technologies

Geographic information technologies (GIT) are essential to many fields of research, such as the preservation and dissemination of cultural heritage buildings, a category which includes traditional underground wine cellars. This article presents a methodology based on research carried out on this type of rural heritage building. The data were acquired using the following sensors: EDM, total station, close-range photogrammetry and laser scanning, and subsequently processed with a specific software which was verified for each case, in order to obtain a satisfactory graphic representation of these underground wine cellars. Two key aspects of this work are the accuracy of the data processing and the visualization of these traditional constructions. The methodology includes an application for geovisualizing these traditional constructions on mobile devices in order to contribute to raising awareness of this unique heritage.

Calibración geométrica de cámaras no métricas. Estudio de metodologías y modelos matemáticos de distorsión

La Fotogrametría, como ciencia y técnica de obtención de información tridimensional del espacio objeto a partir de imágenes bidimensionales, requiere de medidas de precisión y en ese contexto, la calibración geométrica de cámaras ocupa un lugar importante. El conocimiento de la geometría interna de la cámara es fundamental para lograr mayor precisión en las medidas realizadas. En Fotogrametría Aérea se utilizan cámaras métricas (fabricadas exclusivamente para aplicaciones cartográficas), que incluyen objetivos fotográficos con sistemas de lentes complejos y de alta calidad. Pero en Fotogrametría de Objeto Cercano se está trabajando cada vez con más asiduidad con cámaras no métricas, con ópticas de peor calidad que exigen una calibración geométrica antes o después de cada trabajo. El proceso de calibración encierra tres conceptos fundamentales: modelo de cámara, modelo de distorsión y método de calibración. El modelo de cámara es un modelo matemático que aproxima la transformación proyectiva original a la realidad física de las lentes. Ese modelo matemático incluye una serie de parámetros entre los que se encuentran los correspondientes al modelo de distorsión, que se encarga de corregir los errores sistemáticos de la imagen. Finalmente, el método de calibración propone el método de estimación de los parámetros del modelo matemático y la técnica de optimización a emplear. En esta Tesis se propone la utilización de un patrón de calibración bidimensional que se desplaza en la dirección del eje óptico de la cámara, ofreciendo así tridimensionalidad a la escena fotografiada. El patrón incluye un número elevado de marcas, lo que permite realizar ensayos con distintas configuraciones geométricas. Tomando el modelo de proyección perspectiva (o pinhole) como modelo de cámara, se realizan ensayos con tres modelos de distorsión diferentes, el clásico de distorsión radial y tangencial propuesto por D.C. Brown, una aproximación por polinomios de Legendre y una interpolación bicúbica. De la combinación de diferentes configuraciones geométricas y del modelo de distorsión más adecuado, se llega al establecimiento de una metodología de calibración óptima. Para ayudar a la elección se realiza un estudio de las precisiones obtenidas en los distintos ensayos y un control estereoscópico de un panel test construido al efecto. ABSTRACT Photogrammetry, as science and technique for obtaining three-dimensional information of the space object from two-dimensional images, requires measurements of precision and in that context, the geometric camera calibration occupies an important place. The knowledge of the internal geometry of the camera is fundamental to achieve greater precision in measurements made. Metric cameras (manufactured exclusively for cartographic applications), including photographic lenses with complex lenses and high quality systems are used in Aerial Photogrammetry. But in Close Range Photogrammetry is working increasingly more frequently with non-metric cameras, worst quality optical components which require a geometric calibration before or after each job. The calibration process contains three fundamental concepts: camera model, distortion model and method of calibration. The camera model is a mathematical model that approximates the original projective transformation to the physical reality of the lenses. The mathematical model includes a series of parameters which include the correspondents to the model of distortion, which is in charge of correcting the systematic errors of the image. Finally, the calibration method proposes the method of estimation of the parameters of the mathematical modeling and optimization technique to employ. This Thesis is proposing the use of a pattern of two dimensional calibration that moves in the direction of the optical axis of the camera, thus offering three-dimensionality to the photographed scene. The pattern includes a large number of marks, which allows testing with different geometric configurations. Taking the projection model perspective (or pinhole) as a model of camera, tests are performed with three different models of distortion, the classical of distortion radial and tangential proposed by D.C. Brown, an approximation by Legendre polynomials and bicubic interpolation. From the combination of different geometric configurations and the most suitable distortion model, brings the establishment of a methodology for optimal calibration. To help the election, a study of the information obtained in the various tests and a purpose built test panel stereoscopic control is performed.