Calculating the Uncertainty of a Structure from Motion (SfM) Model, Cadman Quarry, Monroe, Washington

Structure from Motion (SfM) is a new form of photogrammetry that automates the rendering of georeferenced 3D models of objects using digital photographs and independently surveyed Ground Control Points (GCPs). This project seeks to quantify the error found in Digital Elevation Models (DEMs) produced using SfM. I modeled a rockslide found at the Cadman Quarry (Monroe, Washington) because the surface is vegetation-free, which is ideal for SfM and Terrestrial LiDAR Scanner (TLS) surveys. By using SfM, TLS, and GPS positioning at the same time, I attempted to find the deviation in the SfM model from the TLS model and GPS points. Using the deviation, I found the Root-Mean-Square Error (RMSE) between the SfM DEM and GPS positions. The RMSE of the SfM model when compared to surveyed GPS points is 17cm. I propagated the uncertainty of the GPS points with the RMSE of the SfM model to find the uncertainty of the SfM model compared to the NAD 1984 datum. The uncertainty of the SfM model compared to the NAD 1984 is 27cm. This study did not produce a model from the TLS that had sufficient resolution on horizontal surfaces to compare to surveyed GPS points.

A low-cost remote sensing system for agricultural applications

This research develops a low cost remote sensing system for use in agricultural applications. The important features of the system are that it monitors the near infrared and it incorporates position and attitude measuring equipment allowing for geo-rectified images to be produced without the use of ground control points. The equipment is designed to be hand held and hence requires no structural modification to the aircraft. The portable remote sensing system consists of an inertia measurement unit (IMU), which is accelerometer based, a low-cost GPS device and a small format false colour composite digital camera. The total cost of producing such a system is below GBP 3000, which is far cheaper than equivalent existing systems. The design of the portable remote sensing device has eliminated bore sight misalignment errors from the direct geo-referencing process. A new processing technique has been introduced for the data obtained from these low-cost devices, and it is found that using this technique the image can be matched (overlaid) onto Ordnance Survey Master Maps at an accuracy compatible with precision agriculture requirements. The direct geo-referencing has also been improved by introducing an algorithm capable of correcting oblique images directly. This algorithm alters the pixels value, hence it is advised that image analysis is performed before image georectification. The drawback of this research is that the low-cost GPS device experienced bad checksum errors, which resulted in missing data. The Wide Area Augmented System (WAAS) correction could not be employed because the satellites could not be locked onto whilst flying. The best GPS data were obtained from the Garmin eTrex (15 m kinematic and 2 m static) instruments which have a highsensitivity receiver with good lock on capability. The limitation of this GPS device is the inability to effectively receive the P-Code wavelength, which is needed to gain the best accuracy when undertaking differential GPS processing. Pairing the carrier phase L1 with the pseudorange C/A-Code received, in order to determine the image coordinates by the differential technique, is still under investigation. To improve the position accuracy, it is recommended that a GPS base station should be established near the survey area, instead of using a permanent GPS base station established by the Ordnance Survey.

HDPR: A Mobile Testbed for Current and Future Rover Technologies

The paper in hand presents a mobile testbed –namely the Heavy Duty Planetary Rover (HDPR)– that was designed and constructed at the Automation and Robotics Laboratories (ARL) of the European Space Agency to fulfill the lab’s internal needs in the context of long range rover exploration as well as in order to provide the means to perform in situ testing of novel algorithms. We designed a rover that: a) is able to reliably perform long range routes, and b) carries an abundant of sensors (both current rover technology and futuristic ones). The testbed includes all the additional hardware and software (i.e. ground control station, UAV, networking, mobile power) to allow the prompt deployment on the field. The reader can find in the paper the description of the system as well as a report on our experiences during our first experiments with the testbed.

On precise three-dimensional environment modeling via UAV-based photogrammetric systems

Abstract : Images acquired from unmanned aerial vehicles (UAVs) can provide data with unprecedented spatial and temporal resolution for three-dimensional (3D) modeling. Solutions developed for this purpose are mainly operating based on photogrammetry concepts, namely UAV-Photogrammetry Systems (UAV-PS). Such systems are used in applications where both geospatial and visual information of the environment is required. These applications include, but are not limited to, natural resource management such as precision agriculture, military and police-related services such as traffic-law enforcement, precision engineering such as infrastructure inspection, and health services such as epidemic emergency management. UAV-photogrammetry systems can be differentiated based on their spatial characteristics in terms of accuracy and resolution. That is some applications, such as precision engineering, require high-resolution and high-accuracy information of the environment (e.g. 3D modeling with less than one centimeter accuracy and resolution). In other applications, lower levels of accuracy might be sufficient, (e.g. wildlife management needing few decimeters of resolution). However, even in those applications, the specific characteristics of UAV-PSs should be well considered in the steps of both system development and application in order to yield satisfying results. In this regard, this thesis presents a comprehensive review of the applications of unmanned aerial imagery, where the objective was to determine the challenges that remote-sensing applications of UAV systems currently face. This review also allowed recognizing the specific characteristics and requirements of UAV-PSs, which are mostly ignored or not thoroughly assessed in recent studies. Accordingly, the focus of the first part of this thesis is on exploring the methodological and experimental aspects of implementing a UAV-PS. The developed system was extensively evaluated for precise modeling of an open-pit gravel mine and performing volumetric-change measurements. This application was selected for two main reasons. Firstly, this case study provided a challenging environment for 3D modeling, in terms of scale changes, terrain relief variations as well as structure and texture diversities. Secondly, open-pit-mine monitoring demands high levels of accuracy, which justifies our efforts to improve the developed UAV-PS to its maximum capacities. The hardware of the system consisted of an electric-powered helicopter, a high-resolution digital camera, and an inertial navigation system. The software of the system included the in-house programs specifically designed for camera calibration, platform calibration, system integration, onboard data acquisition, flight planning and ground control point (GCP) detection. The detailed features of the system are discussed in the thesis, and solutions are proposed in order to enhance the system and its photogrammetric outputs. The accuracy of the results was evaluated under various mapping conditions, including direct georeferencing and indirect georeferencing with different numbers, distributions and types of ground control points. Additionally, the effects of imaging configuration and network stability on modeling accuracy were assessed. The second part of this thesis concentrates on improving the techniques of sparse and dense reconstruction. The proposed solutions are alternatives to traditional aerial photogrammetry techniques, properly adapted to specific characteristics of unmanned, low-altitude imagery. Firstly, a method was developed for robust sparse matching and epipolar-geometry estimation. The main achievement of this method was its capacity to handle a very high percentage of outliers (errors among corresponding points) with remarkable computational efficiency (compared to the state-of-the-art techniques). Secondly, a block bundle adjustment (BBA) strategy was proposed based on the integration of intrinsic camera calibration parameters as pseudo-observations to Gauss-Helmert model. The principal advantage of this strategy was controlling the adverse effect of unstable imaging networks and noisy image observations on the accuracy of self-calibration. The sparse implementation of this strategy was also performed, which allowed its application to data sets containing a lot of tie points. Finally, the concepts of intrinsic curves were revisited for dense stereo matching. The proposed technique could achieve a high level of accuracy and efficiency by searching only through a small fraction of the whole disparity search space as well as internally handling occlusions and matching ambiguities. These photogrammetric solutions were extensively tested using synthetic data, close-range images and the images acquired from the gravel-pit mine. Achieving absolute 3D mapping accuracy of 11±7 mm illustrated the success of this system for high-precision modeling of the environment.

Validação Computacional tendo em vista a Interoperabilidade entre os Veículos Aéreos Não Tripulados

Nos dias de hoje, com o contínuo desenvolvimento e inovação no campo dos UAVs (Unmanned Aerial Vehciles), o mundo já tem como adquiridos os benefícios que estes sistemas podem fornecer. Os benefícios obtidos com a aplicação destes sistemas abrange tanto as forças armadas como industrias e organizações civis. Todas as nações e indústrias querem ter uma cota parte no futuro desta tecnologia. Diferentes UAVs foram desenvolvidos, mas estes, diferem em termos de arquitetura e protocolos de comunicação. Protocolos como o STANAG 4586, MAVLink, JAUS e ROS são só alguns exemplos. A proliferação de informação através destes sistemas e as suas consolas de comando e controlo é uma das principais preocupações, principalmente pelas forças armadas. Uma das principais prioridades é combinar forças de diferentes nações, principalmente pelos membros NATO. A necessidade de uma consola para cada tipo de sistema devido à falta de padronização apresenta assim um problema. É conhecida a necessidade de uma padronização em termos de arquitetura por camadas e de comunicação tendo em vista a interoperabilidade entre estes sistemas. Não existe nenhuma que esteja a ser implementada como documento padrão. Pretende-se que o STANAG 4586 seja o documento padrão para os membros NATO e, por conseguinte, todos os esforços estão direcionados em desenvolver sistemas que o consigam implementar. Os diferentes UAVs já existentes possuem o seu próprio protocolo de comunicação e a alteração de toda a sua estrutura não é fácil. A ideia de fazer uma conversão de linguagens como alternativa surge como uma solução teórica ótima. Utilizando um piloto automático que comunica com a sua consola através da linguagem MAVLink esta dissertação tem como objetivo desenvolver um programa computacional que converta as mensagens MAVLink em STANAG 4586 e estudar se o tempo de conversão é operacionalmente válido tendo em conta os requisitos operacionais dos sistemas.

Feasibility of Electronic Tap-Changing Stabilizers for Medium Voltage Lines-Precedents and New Configurations

Thyristor-based onload tap-changing ac voltage stabilizers are cheap and robust. They have replaced most mechanical tap-changers in low voltage applications from 300 VA to 300 M. Nevertheless, this replacement hardily applies to tap-changers associated to transformers feeding medium-voltage lines (typically 69 kV primary, 34.5 kV line, 10 MVA) which need periodical maintenance of contacts and oil. The Electric Power Research Institute (EPRI) has studied the feasibility of this replacement. It detected economical problems derived from the need for series association of thyristors to manage the high voltages involved, and from the current overload developed under line fault. The paper reviews the configurations used in that field and proposes new solutions, using a compensating transformer in the main circuit and multi-winding coils in the commutating circuit, with reduced overload effect and no series association of thyristors, drastically decreasing their number and rating. The stabilizer can be installed at any point of the line and the electronic circuit can be fixed to ground. Subsequent works study and synthesize several commutating circuits in detail.

Sistema visual para Ground Truth de sistemas autónomos

Este trabalho visa contribuir para o desenvolvimento de um sistema de visão multi-câmara para determinação da localização, atitude e seguimento de múltiplos objectos, para ser utilizado na unidade de robótica do INESCTEC, e resulta da necessidade de ter informação externa exacta que sirva de referência no estudo, caracterização e desenvolvimento de algoritmos de localização, navegação e controlo de vários sistemas autónomos. Com base na caracterização dos veículos autónomos existentes na unidade de robótica do INESCTEC e na análise dos seus cenários de operação, foi efectuado o levantamento de requisitos para o sistema a desenvolver. Foram estudados os fundamentos teóricos, necessários ao desenvolvimento do sistema, em temas relacionados com visão computacional, métodos de estimação e associação de dados para problemas de seguimento de múltiplos objectos . Foi proposta uma arquitectura para o sistema global que endereça os vários requisitos identi cados, permitindo a utilização de múltiplas câmaras e suportando o seguimento de múltiplos objectos, com ou sem marcadores. Foram implementados e validados componentes da arquitectura proposta e integrados num sistema para validação, focando na localização e seguimento de múltiplos objectos com marcadores luminosos à base de Light-Emitting Diodes (LEDs). Nomeadamente, os módulos para a identi cação dos pontos de interesse na imagem, técnicas para agrupar os vários pontos de interesse de cada objecto e efectuar a correspondência das medidas obtidas pelas várias câmaras, método para a determinação da posição e atitude dos objectos, ltro para seguimento de múltiplos objectos. Foram realizados testes para validação e a nação do sistema implementado que demonstram que a solução encontrada vai de encontro aos requisitos, e foram identi cadas as linhas de trabalho para a continuação do desenvolvimento do sistema global.

Control of landslide retrogression by discontinuities: Evidence by the integration of airbone- and ground-based geophysical information

The objective of this work is to present a multitechnique approach to define the geometry, the kinematics, and the failure mechanism of a retrogressive large landslide (upper part of the La Valette landslide, South French Alps) by the combination of airborne and terrestrial laser scanning data and ground-based seismic tomography data. The advantage of combining different methods is to constrain the geometrical and failure mechanism models by integrating different sources of information. Because of an important point density at the ground surface (4. 1 points m?2), a small laser footprint (0.09 m) and an accurate three-dimensional positioning (0.07 m), airborne laser scanning data are adapted as a source of information to analyze morphological structures at the surface. Seismic tomography surveys (P-wave and S-wave velocities) may highlight the presence of low-seismic-velocity zones that characterize the presence of dense fracture networks at the subsurface. The surface displacements measured from the terrestrial laser scanning data over a period of 2 years (May 2008?May 2010) allow one to quantify the landslide activity at the direct vicinity of the identified discontinuities. An important subsidence of the crown area with an average subsidence rate of 3.07 m?year?1 is determined. The displacement directions indicate that the retrogression is controlled structurally by the preexisting discontinuities. A conceptual structural model is proposed to explain the failure mechanism and the retrogressive evolution of the main scarp. Uphill, the crown area is affected by planar sliding included in a deeper wedge failure system constrained by two preexisting fractures. Downhill, the landslide body acts as a buttress for the upper part. Consequently, the progression of the landslide body downhill allows the development of dip-slope failures, and coherent blocks start sliding along planar discontinuities. The volume of the failed mass in the crown area is estimated at 500,000 m3 with the sloping local base level method.

Critical role of the transcriptional repressor neuron-restrictive silencer factor in the specific control of connexin36 in insulin-producing cell lines.

Connexin36 (Cx36) is specifically expressed in neurons and in pancreatic beta-cells. Cx36 functions as a critical regulator of insulin secretion and content in beta-cells. In order to identify the molecular mechanisms that control the beta-cell expression of Cx36, we initiated the characterization of the human 5' regulatory region of the CX36 gene. A 2043-bp fragment of the human CX36 promoter was identified from a human BAC library and fused to a luciferase reporter gene. This promoter region was sufficient to confer specific expression to the reporter gene in insulin-secreting cell lines. Within this 5' regulatory region, a putative neuron-restrictive silencer element conserved between rodent and human species was recognized and binds the neuron-restrictive silencing factor (NRSF/REST). This factor is not expressed in insulin-secreting cells and neurons; it functions as a potent repressor through the recruitment of histone deacetylase to the promoter of neuronal genes. The NRSF-mediated repression of Cx36 in HeLa cells was abolished by trichostatin A, confirming the functional importance of histone deacetylase activity. Ectopic expression, by viral gene transfer, of NRSF/REST in different insulin-secreting beta-cell lines induced a marked reduction in Cx36 mRNA and protein content. Moreover, mutations in the Cx36 neuron-restrictive silencer element relieved the low transcriptional activity of the human CX36 promoter observed in HeLa cells and in INS-1 cells expressing NRSF/REST. The data showed that cx36 gene expression in insulin-producing beta-cell lines is strictly controlled by the transcriptional repressor NRSF/REST indicating that Cx36 participates to the neuronal phenotype of the pancreatic beta-cells.

Reactivity spectrum of 30 monoclonal antimelanoma antibodies to a panel of 28 melanoma and control cell lines.

Thirty monoclonal antibodies from eight laboratories exchanged after the First Workshop on Monoclonal Antibodies to Human Melanoma held in March 1981 at NIH were tested in an antibody-binding radioimmunoassay using a panel of 28 different cell lines. This panel included 12 melanomas, three neuroblastomas, four gliomas, one retinoblastoma, four colon carcinomas, one lung carcinoma, one cervical carcinoma, one endometrial carcinoma, and one breast carcinoma. The reactivity pattern of the 30 monoclonal antibodies tested showed that none of them were directed against antigens strictly restricted to melanoma, but that several of them recognize antigenic structures preferentially expressed on melanoma cells. A large number of antibodies were found to crossreact with gliomas and neuroblastomas. Thus, they seem to recognize neuroectoderm associated differentiation antigens. Four monoclonal antibodies produced in our laboratory were further studied for the immunohistological localization of melanoma associated antigens on fresh tumor material. In a three-layer biotin-avidin-peroxidase system each antibody showed a different staining pattern with the tumor cells, suggesting that they were directed against different antigens.

Design and Analysis of Microstrip Lines with EBG-Backed Ground Planes of Different Geometrical Shapes

Propagation of electromagnetic waves through a microstrip line with 2D electromagnetic baud gap (EBG) structures of different geometrical shapes in the ground plane is investigated in this paper. Using transmission-line theory, the design equations for EBG structures are calculated. The measured, numerical. and simulated results are in gone) agreement

Procedures of quality control and data analysis of multi-site ground-based observations for the absolute flux calibration of Gaia

The Gaia space mission is a major project for the European astronomical community. As challenging as it is, the processing and analysis of the huge data-flow incoming from Gaia is the subject of thorough study and preparatory work by the DPAC (Data Processing and Analysis Consortium), in charge of all aspects of the Gaia data reduction. This PhD Thesis was carried out in the framework of the DPAC, within the team based in Bologna. The task of the Bologna team is to define the calibration model and to build a grid of spectro-photometric standard stars (SPSS) suitable for the absolute flux calibration of the Gaia G-band photometry and the BP/RP spectrophotometry. Such a flux calibration can be performed by repeatedly observing each SPSS during the life-time of the Gaia mission and by comparing the observed Gaia spectra to the spectra obtained by our ground-based observations. Due to both the different observing sites involved and the huge amount of frames expected (≃100000), it is essential to maintain the maximum homogeneity in data quality, acquisition and treatment, and a particular care has to be used to test the capabilities of each telescope/instrument combination (through the “instrument familiarization plan”), to devise methods to keep under control, and eventually to correct for, the typical instrumental effects that can affect the high precision required for the Gaia SPSS grid (a few % with respect to Vega). I contributed to the ground-based survey of Gaia SPSS in many respects: with the observations, the instrument familiarization plan, the data reduction and analysis activities (both photometry and spectroscopy), and to the maintenance of the data archives. However, the field I was personally responsible for was photometry and in particular relative photometry for the production of short-term light curves. In this context I defined and tested a semi-automated pipeline which allows for the pre-reduction of imaging SPSS data and the production of aperture photometry catalogues ready to be used for further analysis. A series of semi-automated quality control criteria are included in the pipeline at various levels, from pre-reduction, to aperture photometry, to light curves production and analysis.

Implementazione di un algoritmo di navigazione autonoma di alto livello e sviluppo software di una Control Ground Station

Caratteristiche hardware di un rover terrestre (progetto SHERPA). Implementazione tramite il framework ROS di un algoritmo di alto livello di navigazione autonoma basato su due possibili algoritmi di basso livello: LOS (Lightweight Object Streaming developed by BlueBotics) o Navigation Stack. Sviluppo di una Control Ground Station (Java) basata su: protocollo SSH2 oppure sfruttando la libreria LOS.

14 ground-penetrating radar lines of Area 5 - Periglacial outwash plain from Potter Cove, King George Island, Antarctic Peninsula

During a field campaign in the Austral spring 2012 the sedimentary architecture of a periglacial flood plain at the northeastern coast of Potter Peninsula (Area 5) was revealed using ground-penetrating radar (GPR, Geophysical Survey Systems, Inc. SIR-3000). 14 profiles were collected using a mono-static 200 MHz antenna operated in common offset mode. Trace increment was set to 0.05 m. A differential global-positioning system (dGPS, Leica GS09) was used to obtain topographical information along the GPR lines. GPR data are provided in RADAN-Format, dGPS coordinates are provided in ascii format; projection is UTM (WGS 84, zone 21S).

31 ground-penetrating radar lines of Area 3 - Beach ridge plain (high wave energy) from Maxwell Bay, King George Island, Antarctic Peninsula

During a field campaign in the Austral spring 2012 the sedimentary architecture of a polar gravel-beach system at the southern coast of Potter Peninsula (Area 3) was revealed using ground-penetrating radar (GPR, Geophysical Survey Systems, Inc. SIR-3000). 31 profiles were collected using a mono-static 200 MHz antenna operated in common offset mode. Trace increment was set to 0.05 m. A differential global-positioning system (dGPS, Leica GS09) was used to obtain topographical information along the GPR lines. GPR data are provided in RADAN-Format, dGPS coordinates are provided in ascii format; projection is UTM (WGS 84, zone 21S).