bluuebunny/crossref_metadata_2025 huggingface dataset:
Combination of Grinding and Wet Welding to Repair Localized Cracking in T-Welded Connections
Authors: Méndez Gerardo Terán , Cuamatzi-Meléndez Rubén , Hernández Apolinar Albiter
Published: May 2014

This paper presents experimental research work on the combination of grinding and wet welding techniques to repair T-welded connections employed in the construction of offshore structures. A longitudinal rectangular grinding profile was performed at the weld toe of T-welded connections for localized cracking material removal. Two different grinding depths of 6 mm and 10 mm were performed in the welded connections to eliminate two different level of damage depth. Subsequent wet welding was applied in the grinded region to repair the grinded material. The wet welding was performed in a hyperbaric chamber simulating three different water depths: 50 m, 70 m and 100 m (shallow water). Once the combined repair techniques were performed, further experimental work was done to characterize the mechanical behavior of the repaired structures. The mechanical characterization was done with tensile, Charpy tests and Vickers Hardness tests. The region of interest from the structures was the weld toes the grinded-wet welding repair of the T-welded connections. Subsequent scanning electron microscopy (SEM) was also performed to examine the developed microstructures in the T-welded connection. The results showed that the combination of the repair techniques can restore the mechanical properties of the damaged structures. This was demonstrated by the measurement of the ultimate tensile strength, which were similar to those measured with no repair applied techniques. But the Charpy energy values were quite lower to those previously measured. This behavior was attributed to the level of porosity formed by the high level of gases created during the welding process for the simulated water depths, which were more severe at the higher water depth resulting in pore formation
Electrochemical Characterization of X60 Steel Corrosion at Different Overvoltages: A Cathodic Protection Study
Authors: Trejo-Atecas Brenda , Orozco-Cruz Ricardo , Contreras-Cuevas Antonio , Galván-Martínez Ricardo
Published: May 2014

This paper presents an electrochemical characterization of X60 steel corrosion using polarization curves. In order to get a surface analysis, a Scanning Electron Microscopy (SEM) was used. Analyses by Energy Dispersive Spectroscopy (EDS) were done to characterize the corrosion products films formed on surface of the steel sample at the different overvoltages studied. The electrolyte was a synthetic soil solution and all electrochemical parameter was measured at room temperature, atmospheric pressure and 24 hours of the total exposure time. It is important to point out that these parameters were measured in the protection potential (versus saturated calomel electrode, SCE) and at different overvoltages. The results of the polarization curves show that the corrosion rate increased as the overvoltage also increased and this behaviour was corroborated by the superficial analysis obtained by SEM; where the corrosion morphology was localized and the aggresivity increased with the overvoltage. In addition, in all overvoltages, the anodic reaction was limited by a mass transfer process. A localized corrosion form was found in all tests.
Wanneer een twee word: ’n Perspektief op resente gebeure in die Nederduitsch Hervormde Kerk van Afrika
Authors: Dreyer Wim A.
Published: May 2014

When one becomes two: A perspective on recent events in the Netherdutch Reformed Church of Africa. On 28 July 2013 13 congregations of the Netherdutch Reformed Church of Africa (Nederduitsch Hervormde Kerk van Afrika) declared themselves independent and constituted as the ‘Geloofsbond van Hervormde Gemeentes’. This contribution examines the recent historical background to this event as well as several contributing factors such as the role of the media, the role of organisations, differences in theology as well as ideological differences. The conclusion is reached that a tension-filled discourse between confessional and critical theology, linked to clear ideological views, were the main contributing factors to divisions in the church. The contribution concludes with a discussion of some implications of these events from the perspective of church polity.
A case of septicemia due to Chyresobacterium indologenes producing bla NDM-1
Authors: Khajuria Atul , Praharaj Ashok Kumar , Kumar Mahadevan , Grover Naveen
Published: May 2014

A multidrug resistant Chyresobacterium indologenes was isolated from blood in a case of septicemia. The organism was resistant to carbapenems and was positive for bla NDM-1 ; transferable through plasmid.
Kenny-Caffey syndrome type 1
Authors: Jabbour Tony El , Aboursheid Tarek , Keifo Mohammad Baraa , Maksoud Ismael , Alasmar Diana
Published: May 2014

Kenny-Caffey syndrome type 1 is a rare hereditary skeletal disorder. We present here a documented case of a 7-month-old girl with the characteristic symptoms of growth retardation, dysmorphic features, and hypoparathyroidism.
Cryptosporidiosis in HIV/AIDS Patients in Kenya: Clinical Features, Epidemiology, Molecular Characterization and Antibody Responses
Authors: Wanyiri Jane W. , Kanyi Henry , Maina Samuel , Wang David E. , Steen Aaron , Ngugi Paul , Kamau Timothy , Waithera Tabitha , O'Connor Roberta , Gachuhi Kimani , Wamae Claire N. , Mwamburi Mkaya , Ward Honorine D.
Published: May 2014

We investigated the epidemiological and clinical features of cryptosporidiosis, the molecular characteristics of infecting species and serum antibody responses to three Cryptosporidium-specific antigens in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients in Kenya. Cryptosporidium was the most prevalent enteric pathogen and was identified in 56 of 164 (34%) of HIV/AIDS patients, including 25 of 70 (36%) with diarrhea and 31 of 94 (33%) without diarrhea. Diarrhea in patients exclusively infected with Cryptosporidium was significantly associated with the number of children per household, contact with animals, and water treatment. Cryptosporidium hominis was the most prevalent species and the most prevalent subtype family was Ib. Patients without diarrhea had significantly higher serum IgG levels to Chgp15, Chgp40 and Cp23, and higher fecal IgA levels to Chgp15 and Chgp40 than those with diarrhea suggesting that antibody responses to these antigens may be associated with protection from diarrhea and supporting further investigation of these antigens as vaccine candidates.
An Evaluation of Methods for Assessing the Quality of Case Management for Inpatients with Malaria in Benin
Authors: Mace Kimberly E. , Gueye Abdou Salam , Lynch Michael F. , Tassiba Esther M. , Rowe Alexander K.
Published: May 2014

To improve healthcare quality for hospitalized patients with malaria in Benin, a feasible and valid evaluation method is needed. Because observation of inpatients is challenging, chart abstraction is an attractive option. However, the quality of inpatient charts is unknown. We employed three methods in five hospitals to assess 11 signs of malaria and severe disease: 1) chart abstraction (probability sample of inpatients), 2) chart abstraction compared to interviews of inpatients and health workers (HWs), and 3) abstraction from charts of recently discharged inpatients compared to interviews with HWs. Method 1 showed that of 473 malaria signs (from 43 charts), 178 (38%, 95% confidence interval 24–51%) were documented. Method 2 showed that 96% (45 of 47) of documented signs were valid. Method 3 suggests that 65% (36 of 55) of non-documented signs were assessed (but not documented) by HWs. Chart abstraction was feasible and documented data were valid, but results should be interpreted cautiously in consideration of low levels of documentation.
Safety and Immunogenicity of a Rederived, Live-Attenuated Dengue Virus Vaccine in Healthy Adults Living in Thailand: A Randomized Trial
Authors: Watanaveeradej Veerachai , Gibbons Robert V. , Simasathien Sriluck , Nisalak Ananda , Jarman Richard G. , Kerdpanich Angkool , Tournay Elodie , De La Barrerra Rafael , Dessy Francis , Toussaint Jean-François , Eckels Kenneth H. , Thomas Stephen J. , Innis Bruce L.
Published: May 2014

Safety and immunogenicity of two formulations of a live-attenuated tetravalent dengue virus (TDEN) vaccine produced using rederived master seeds from a precursor vaccine were tested against a placebo control in a phase II, randomized, double blind trial (NCT00370682). Two doses were administered 6 months apart to 120 healthy, predominantly flavivirus-primed adults (87.5% and 97.5% in the two vaccine groups and 92.5% in the placebo group). Symptoms and signs reported after vaccination were mild to moderate and transient. There were no vaccine-related serious adverse events or dengue cases reported. Asymptomatic, low-level viremia (dengue virus type 2 [DENV-2], DENV-3, or DENV-4) was detected in 5 of 80 vaccine recipients. One placebo recipient developed a subclinical natural DENV-1 infection. All flavivirus-unprimed subjects and at least 97.1% of flavivirus-primed subjects were seropositive to antibodies against all four DENV types 1 and 3 months post-TDEN dose 2. The TDEN vaccine was immunogenic with an acceptable safety profile in flavivirus-primed adults.
Burden of Dengue Infection and Disease in a Pediatric Cohort in Urban Sri Lanka
Authors: Tissera Hasitha , Amarasinghe Ananda , De Silva Aruna Dharshan , Kariyawasam Pradeep , Corbett Kizzmekia S. , Katzelnick Leah , Tam Clarence , Letson G. William , Margolis Harold S. , de Silva Aravinda M.
Published: May 2014

Dengue is the most significant arthropod-borne viral infection of humans. Persons infected with dengue viruses (DENV) have subclinical or clinically apparent infections ranging from undifferentiated fever to dengue hemorrhagic fever/shock syndrome. Although recent studies estimated that the Indian subcontinent has the greatest burden of DENV infection and disease worldwide, we do not have reliable, population-based estimates of the incidence of infection and disease in this region. The goal of this study was to follow-up a cohort of 800 children living in a heavily urbanized area of Colombo, Sri Lanka to obtain accurate estimates of the incidence of DENV infection and disease. Annual blood samples were obtained from all children to estimate dengue seroprevalence at enrollment and to identify children exposed to new DENV infections during the study year. Blood was also obtained from any child in whom fever developed over the course of the study year to identify clinically apparent DENV infections. At enrollment, dengue seroprevalence was 53.07%, which indicated high transmission in this population. Over the study year, the incidence of DENV infection and disease were 8.39 (95% confidence interval = 6.56–10.53) and 3.38 (95% confidence interval = 2.24–4.88), respectively, per 100 children per year. The ratio of clinically inapparent to apparent infections was 1.48. These results will be useful for obtaining more accurate estimates of the burden of dengue in the region and for making decisions about testing and introduction of vaccines.
Mycobacterium tuberculosis Isolates from Single Outpatient Clinic in Panama City Exhibit Wide Genetic Diversity
Authors: Sambrano Dilcia , Correa Ricardo , Almengor Pedro , Domínguez Amada , Vega Silvio , Goodridge Amador
Published: May 2014

Understanding Mycobacterium tuberculosis biodiversity and transmission is significant for tuberculosis control. This short report aimed to determine the genetic diversity of M. tuberculosis isolates from an outpatient clinic in Panama City. A total of 62 M. tuberculosis isolates were genotyped by 12 loci mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) and Spoligotyping. Forty-five (72.6%) of the isolates showed unique MIRU-VNTR genotypes, and 13 (21%) of the isolates were grouped into four clusters. Four isolates showed polyclonal MIRU-VNTR genotypes. The MIRU-VNTR Hunter-Gaston discriminatory index reached 0.988. The Spoligotyping analysis revealed 16 M. tuberculosis families, including Latin American-Mediterranean, Harlem, and Beijing. These findings suggest a wide genetic diversity of M. tuberculosis isolates at one outpatient clinic. A detailed molecular epidemiology survey is now warranted, especially following second massive immigration for local Panama Canal expansion activities.
Structuring Clinical Workflows for Diabetes Care
Authors: Lasierra N. , Oberbichler S. , Toma I. , Fensel A. , Hoerbst A. , Schweitzer M.
Published: May 2014

Background: Electronic health records (EHRs) play an important role in the treatment of chronic diseases such as diabetes mellitus. Although the interoperability and selected functionality of EHRs are already addressed by a number of standards and best practices, such as IHE or HL7, the majority of these systems are still monolithic from a user-functionality perspective. The purpose of the OntoHealth project is to foster a functionally flexible, standards-based use of EHRs to support clinical routine task execution by means of workflow patterns and to shift the present EHR usage to a more comprehensive integration concerning complete clinical workflows.

Objectives: The goal of this paper is, first, to introduce the basic architecture of the proposed OntoHealth project and, second, to present selected functional needs and a functional categorization regarding workflow-based interactions with EHRs in the domain of diabetes.

Methods: A systematic literature review regarding attributes of workflows in the domain of diabetes was conducted. Eligible references were gathered and analyzed using a qualitative content analysis. Subsequently, a functional workflow categorization was derived from diabetes-specific raw data together with existing general workflow patterns.

Results: This paper presents the design of the architecture as well as a categorization model which makes it possible to describe the components or building blocks within clinical workflows. The results of our study lead us to identify basic building blocks, named as actions, decisions, and data elements, which allow the composition of clinical workflows within five identified contexts.

Conclusions: The categorization model allows for a description of the components or building blocks of clinical workflows from a functional view.

Citation: Schweitzer M, Lasierra N, Oberbichler S, Toma I, Fensel A, Hoerbst A. Structuring clinical workflows for diabetes care: An overview of the OntoHealth approach. Appl Clin Inf 2014; 5: 512–526 http://dx.doi.org/10.4338/ACI-2014-04-RA-0039
Hydroclimatological influences at multi-spatial scales on recently increased droughts in China's largest freshwater lake
Authors: Liu Y. , Wu G.
Published: May 2014

Abstract. Lake droughts are the consequences of climatic, hydrologic and anthropogenic influences. It may produce substantial impacts on local water sources, inhabitants and economy, but few studies have determined the contributions from the individual influences, especially under the changing climate, which is of highly valuable for policymakers to make effective adaption. This study proposes to use a multi-scale hydroclimatic analysis for the determination, taking Poyang Lake as an example. It is the China's largest freshwater lake, which has been undergoing drastic hydrological alterations in recent decade. Our analysis demonstrates that in the recent decade the lake droughts worsened in terms of duration, frequency, magnitude and severity, and intensified in magnitude significantly. At the lake region, water deficiency severed as the hydroclimatic foundation for the worsening droughts. Overall contribution to the lake droughts included decreased inflow (45%), increased outflow (24%), reduced local precipitation (23%), and increased evapotranspiration (8%). At the basin scale, the decreased inflow was ascribed to reduced basin-scale precipitation (82%) and increased evapotranspiration (18%). The increased outflow was principally controlled by the weakened blocking effects of the Yangtze River, which serves as a boundary condition of Poyang Lake. Water impoundments of the Three Gorges Dam (TGD) established upstream should not be responsible for the increased drought occurrence, but they may have enhanced the drought magnitude with a limit contribution. The findings provide an example of intensified lake droughts, and offer an insightful view into lake droughts under the changing climate and anthropogenic influences. It should be valuable for improving our understanding and for promoting effective climate adaptation and water resources management practices.
Identifying the origin and geochemical evolution of groundwater using hydrochemistry and stable isotopes in Subei Lake Basin, Ordos energy base, Northwestern China
Authors: Liu F. , Song X. , Yang L. , Zhang Y. , Han D. , Ma Y. , Bu H.
Published: May 2014

Abstract. A hydrochemical and isotopic study was conducted in Subei Lake Basin, northwestern China, to identify the origin and geochemical evolution of groundwater. Water samples were collected, major ions and stable isotopes (δ18O, δ D) were analyzed. In terms of hydrogeological conditions in study area, groundwater can be classified into three types: the Quaternary groundwater, the shallow Cretaceous groundwater, the deep Cretaceous groundwater. Piper diagram and correlation analysis were used to reveal the hydrochemical characteristics of water resources. The dominant water type of lake water was Na-Cl type, which was controlled by strong evaporation and recharge from overland flow and groundwater; the predominant hydrochemical types for groundwater were Ca-HCO3, Na-HCO3, and mixed Ca · Na · Mg-HCO3 types, the groundwater chemistry is mainly controlled by dissolution/precipitation of anhydrite, gypsum, halite and calcite. The dedolomitization and cation exchange are also important factors. Rock weathering is confirmed to play a leading role in the mechanisms responsible for the chemical compositions of groundwater. The stable isotopic values of oxygen and hydrogen in groundwater are close to the local meteoric water line, showing that groundwater is of meteoric origin. The deep Cretaceous groundwater is depleted in heavy isotopes, compared to shallow Cretaceous groundwater. The hydrogen and oxygen isotopes signatures in deep Cretaceous groundwater may show a paleorecharge effect that the deep Cretaceous groundwater was recharged during a geologic period when the climate was wetter and colder than today. Due to strong evaporation effect and dry climatic conditions, heavy isotopes are more enriched in lake water than groundwater. The hydrochemical and isotopic information of utmost importance has been provided to decision-makers by the present study so that a sustainable water resources management policy could be designed for the Ordos energy base.
Automatic road sign detecion and classification based on support vector machines and HOG descriptos
Authors: Adam A. , Ioannidis C.
Published: May 2014

Abstract. This paper examines the detection and classification of road signs in color-images acquired by a low cost camera mounted on a moving vehicle. A new method for the detection and classification of road signs is proposed based on color based detection, in order to locate regions of interest. Then, a circular Hough transform is applied to complete detection taking advantage of the shape properties of the road signs. The regions of interest are finally represented using HOG descriptors and are fed into trained Support Vector Machines (SVMs) in order to be recognized. For the training procedure, a database with several training examples depicting Greek road sings has been developed. Many experiments have been conducted and are presented, to measure the efficiency of the proposed methodology especially under adverse weather conditions and poor illumination. For the experiments training datasets consisting of different number of examples were used and the results are presented, along with some possible extensions of this work.
Reconstructing 3D coastal cliffs from airborne oblique photographs without ground control points
Authors: Dewez T. J. B.
Published: May 2014

Abstract. Coastal cliff collapse hazard assessment requires measuring cliff face topography at regular intervals. Terrestrial laser scanner techniques have proven useful so far but are expensive to use either through purchasing the equipment or through survey subcontracting. In addition, terrestrial laser surveys take time which is sometimes incompatible with the time during with the beach is accessible at low-tide. By comparison, structure from motion techniques (SFM) are much less costly to implement, and if airborne, acquisition of several kilometers of coastline can be done in a matter of minutes. In this paper, the potential of GPS-tagged oblique airborne photographs and SFM techniques is examined to reconstruct chalk cliff dense 3D point clouds without Ground Control Points (GCP). The focus is put on comparing the relative 3D point of views reconstructed by Visual SFM with their synchronous Solmeta Geotagger Pro2 GPS locations using robust estimators. With a set of 568 oblique photos, shot from the open door of an airplane with a triplet of synchronized Nikon D7000, GPS and SFM-determined view point coordinates converge to X: ±31.5 m; Y: ±39.7 m; Z: ±13.0 m (LE66). Uncertainty in GPS position affects the model scale, angular attitude of the reference frame (the shoreline ends up tilted by 2°) and absolute positioning. Ground Control Points cannot be avoided to orient such models.
Image pre-processing for optimizing automated photogrammetry performances
Authors: Guidi G. , Gonizzi S. , Micoli L. L.
Published: May 2014

Abstract. The purpose of this paper is to analyze how optical pre-processing with polarizing filters and digital pre-processing with HDR imaging, may improve the automated 3D modeling pipeline based on SFM and Image Matching, with special emphasis on optically non-cooperative surfaces of shiny or dark materials. Because of the automatic detection of homologous points, the presence of highlights due to shiny materials, or nearly uniform dark patches produced by low reflectance materials, may produce erroneous matching involving wrong 3D point estimations, and consequently holes and topological errors on the mesh originated by the associated dense 3D cloud. This is due to the limited dynamic range of the 8 bit digital images that are matched each other for generating 3D data. The same 256 levels can be more usefully employed if the actual dynamic range is compressed, avoiding luminance clipping on the darker and lighter image areas. Such approach is here considered both using optical filtering and HDR processing with tone mapping, with experimental evaluation on different Cultural Heritage objects characterized by non-cooperative optical behavior. Three test images of each object have been captured from different positions, changing the shooting conditions (filter/no-filter) and the image processing (no processing/HDR processing), in order to have the same 3 camera orientations with different optical and digital pre-processing, and applying the same automated process to each photo set.
Photogrammetric Applications of Immersive Video Cameras
Authors: Kwiatek K. , Tokarczyk R.
Published: May 2014

Abstract. The paper investigates immersive videography and its application in close-range photogrammetry. Immersive video involves the capture of a live-action scene that presents a 360° field of view. It is recorded simultaneously by multiple cameras or microlenses, where the principal point of each camera is offset from the rotating axis of the device. This issue causes problems when stitching together individual frames of video separated from particular cameras, however there are ways to overcome it and applying immersive cameras in photogrammetry provides a new potential. The paper presents two applications of immersive video in photogrammetry. At first, the creation of a low-cost mobile mapping system based on Ladybug®3 and GPS device is discussed. The amount of panoramas is much too high for photogrammetric purposes as the base line between spherical panoramas is around 1 metre. More than 92 000 panoramas were recorded in one Polish region of Czarny Dunajec and the measurements from panoramas enable the user to measure the area of outdoors (adverting structures) and billboards. A new law is being created in order to limit the number of illegal advertising structures in the Polish landscape and immersive video recorded in a short period of time is a candidate for economical and flexible measurements off-site. The second approach is a generation of 3d video-based reconstructions of heritage sites based on immersive video (structure from immersive video). A mobile camera mounted on a tripod dolly was used to record the interior scene and immersive video, separated into thousands of still panoramas, was converted from video into 3d objects using Agisoft Photoscan Professional. The findings from these experiments demonstrated that immersive photogrammetry seems to be a flexible and prompt method of 3d modelling and provides promising features for mobile mapping systems.
UAV platforms for cultural heritage survey: first results
Authors: Lo Brutto M. , Garraffa A. , Meli P.
Published: May 2014

Abstract. The use of Unmanned Aerial Vehicle (UAV) is becoming very common for photogrammetric survey especially due to numerous advantages compared to "traditional" aerial photogrammetry. The work carried out describes the first results obtained using different UAV systems for Cultural Heritage surveys. The study was performed acquiring two different datasets on an archaeological site and a "land art" site respectively. These datasets have different characteristics in relation to the extension of the surveyed areas, the used platform, the flight parameters. A Computer Vision approach has been used to produce 3D models and ortho-images with a very high level of detail. Some tests were also carried out to evaluate the metric accuracy of the images orientations and 3D models.
A line-based approach for precise extraction of road and curb region from mobile mapping data
Authors: Miyazaki R. , Yamamoto M. , Hanamoto E. , Izumi H. , Harada K.
Published: May 2014

Abstract. Planar structure detection from point clouds is important process in many applications such as maintenance of infrastructure facility including roads and curbs because most artificial structures consists of planar surfaces. The Mobile Mapping System can obtain a large amount of points with traveling at a standard speed. However, in the case that the high-end laser scanning system is equipped, the distribution density of points is uneven. In the point-based method, this situation causes the problem to the method of calculating geometric information using neighborhood points. In this paper, we propose a line-based region growing method in order to detect planar structures with precise boundary from point clouds with uneven distribution density of points. The precise boundary of a planar structure is maintained by appropriately creating line segments from the input clouds. We adapt the definition of neighborhood and the estimation of the normal vector to the line-based region growing. The evaluation by comparing our result with manually extracted points shows that more than 98% of curb points are detected. And, about 90% of the boundary points between a road and a curb are detected with less than 0.005 meters of the distance error.
Photogrammetric Archaeological Survey with UAV
Authors: Mouget A. , Lucet G.
Published: May 2014

Abstract. This document describes a way to obtain various photogrammetric products from aerial photograph using a drone. The aim of the project was to develop a methodology to obtain information for the study of the architecture of pre-Columbian archaeological sites in Mexico combining the manoeuvrability and low cost of a drone with the accuracy of the results of the open source photogrammetric MicMac software. It presents the UAV and the camera used, explains how to manipulate it to carry out stereoscopic photographs, the flight and camera parameters chosen, the treatments performed to obtain orthophotos and 3D models with a centimetric resolution, and finally outlines the quality of the results.
Survey turned into HBIM: the restoration and the work involved concerning the Basilica di Collemaggio after the earthquake (L'Aquila)
Authors: Oreni D. , Brumana R. , Della Torre S. , Banfi F. , Barazzetti L , Previtali M.
Published: May 2014

Abstract. The HBIM of the Basilica di Collemaggio in L'Aquila is part of the restoration project of the building seriously damaged by the earthquake in 2009. The project "Ripartire da Collemaggio", funded by ENIservizi, involves an interdisciplinary group called to work together toward a common goal: the need of security of the structures and the need of conservation of the architectonic value of the Basilica. Starting from the photogrammetric and laser scanning survey, interpretation and modelling were needed to create a detailed HBIM to manage the phases of analysis, simulation of structural behavior, economic evaluation of the project, and final restoration. This paper described the generation of the HBIM and its use in the on-going restoration project with a particular attention to the procedures used to preserve the complexity given by photogrammetric and laser scanning data.
Detection of harvested trees in forests from repeated high density airborne laser scanning
Authors: Pietrzyk P. J. , Lindenbergh R. C.
Published: May 2014

Abstract. Identification of harvested and fallen trees is a prerequisite for the detection and measurement of changes in forests. This paper presents a three step approach to monitor harvested and fallen trees based on direct comparison of repeated high density airborne LIDAR data. In a first step differences between data sets are obtained from a point to point comparison, such that the data can be reduced to the deviating points only. Secondly, the resulting points are clustered into spatially connected regions using region growing. Finally, individual trees are extracted from the clusters by analysing their relative proximity and by analysing geometric properties of points in the clusters. Two data sets, acquired at a four year interval and covering a forest with mainly deciduous trees, are compared. First results show that most points relating to a change can be extracted and that clustering of these with region growing enables us to efficiently separate harvested and fallen trees from the remaining trees. Grouped harvested trees could not be separated using the region growing approach due to touching crowns. Segmentation of these using spectral clustering however identified individual regions well, but the results depend mainly on the pre-defined number of clusters. Crowns of grouped trees can be therefore separated if the number of trees is known.
Towards automatic indoor reconstruction of cluttered building rooms from point clouds
Authors: Previtali M. , Barazzetti L. , Brumana R. , Scaioni M.
Published: May 2014

Abstract. Terrestrial laser scanning is increasingly used in architecture and building engineering for as-built modelling of large and medium size civil structures. However, raw point clouds derived from laser scanning survey are generally not directly ready for generation of such models. A manual modelling phase has to be undertaken to edit and complete 3D models, which may cover indoor or outdoor environments. This paper presents an automated procedure to turn raw point clouds into semantically-enriched models of building interiors. The developed method mainly copes with a geometric complexity typical of indoor scenes with prevalence of planar surfaces, such as walls, floors and ceilings. A characteristic aspect of indoor modelling is the large amount of clutter and occlusion that may characterize any point clouds. For this reason the developed reconstruction pipeline was designed to recover and complete missing parts in a plausible way. The accuracy of the presented method was evaluated against traditional manual modelling and showed comparable results.
Integration of image and range-based techniques for surveying complex architectures
Authors: Russo M. , Manferdini A.M.
Published: May 2014

Abstract. In the last decade the Cultural Heritage field has deeply benefited from the opportunities of collecting accurate and detailed 3D information of sites and artifacts using both image- and range-based techniques. Since few years ago these technologies were not so extensively used, mainly because they were very expensive, required expertise and the pipeline and procedures related to their use were not straightforward, nor consolidated. But in the last years significant improvements in the digital survey technologies have been reached, with the principal scope of simplifying reality-based survey procedure and providing a series of different solutions that combine the automation of processes with accuracy and resolution performances. In addition to these aspects, the lowering of costs and the consequent widespread use of some survey solutions, such as, for example, range-based, as well as terrestrial and UAV image-based ones, have recently given strong impulse to the widening of use of these technologies in the Cultural Heritage field. As a consequence, this range of possibilities shows that in this field, where case studies have peculiar geometric and radiometric characteristics and survey conditions are often unique, preliminary investigations and evaluations are mandatory in order to define the most suitable solution to adopt. In this context, this paper presents preliminary results from the Santa Maria di Pomposa survey project, with the purpose of starting a deep investigation on the integration of 3D digital technologies and how they can provide complete and multi-scalar information about complex architectures. This purpose is particularly important in case studies where analysis have to be conducted at different scales of complexity. Structural analysis are just an example of the need to easily handle complete and global information that have to be deeply and detailed analyzed, eventually showing the behavior of structures over time. Within the adopted methodology, the comparison of results obtained using different approaches represents an indispensable step in order to evaluate and select the most reliable and suitable solutions to adopt within the final integrations process.
Automatic reconstruction of skeletal structures from TLS forest scenes
Authors: Schilling A. , Maas H.-G.
Published: May 2014

Abstract. Detailed information about 3D forest structure is vital in forest science for analyzing the spatio-temporal development of plants as well as precise harvest forecasting in forest industry. Up to now, the majority of methods focus on complete structural reconstruction of trees from multiple scans, which might not be a suitable starting point with respect to modeling forest scenes over larger areas. For this reason, we propose a strategy to obtain skeletal structures of trees from single scans following a divide-and-conquer approach well-known from computer science. First, we split the range image into components representing surface patches and trace each component’s boundary, which is essential for our skeleton retrieval method. Therefore, we propose an extension to standard boundary tracing that takes a component’s interior depth discontinuities into account. Second, each component is processed separately: A 2D skeleton is obtained via the Voronoi Diagram and refined. Subsequently, a component is segmented into subsets of points depending on their proximity to skeleton nodes. Afterwards, the skeleton is split into paths and a Principal Curve is computed from each path’s point cluster in order to retrieve the component shape as a set of 3D polygonal lines. Our method retrieves the intricate branching structure of components representing tree crown parts reliably and efficiently. The results are fitting with respect to a visual inspection. At present, results are fragments of tree skeletons, but it opens an attractive perspective to complete tree skeletons from skeletal parts, which we currently regard as future work.
A new approach towards image based virtual 3D city modeling by using close range photogrammetry
Authors: Singh S.P. , Jain K. , Mandla V.R.
Published: May 2014

Abstract. 3D city model is a digital representation of the Earth's surface and it’s related objects such as building, tree, vegetation, and some manmade feature belonging to urban area. The demand of 3D city modeling is increasing day to day for various engineering and non-engineering applications. Generally three main image based approaches are using for virtual 3D city models generation. In first approach, researchers used Sketch based modeling, second method is Procedural grammar based modeling and third approach is Close range photogrammetry based modeling. Literature study shows that till date, there is no complete solution available to create complete 3D city model by using images. These image based methods also have limitations This paper gives a new approach towards image based virtual 3D city modeling by using close range photogrammetry. This approach is divided into three sections. First, data acquisition process, second is 3D data processing, and third is data combination process. In data acquisition process, a multi-camera setup developed and used for video recording of an area. Image frames created from video data. Minimum required and suitable video image frame selected for 3D processing. In second section, based on close range photogrammetric principles and computer vision techniques, 3D model of area created. In third section, this 3D model exported to adding and merging of other pieces of large area. Scaling and alignment of 3D model was done. After applying the texturing and rendering on this model, a final photo-realistic textured 3D model created. This 3D model transferred into walk-through model or in movie form. Most of the processing steps are automatic. So this method is cost effective and less laborious. Accuracy of this model is good. For this research work, study area is the campus of department of civil engineering, Indian Institute of Technology, Roorkee. This campus acts as a prototype for city. Aerial photography is restricted in many country and high resolution satellite images are costly. In this study, proposed method is based on only simple video recording of area. Thus this proposed method is suitable for 3D city modeling. Photo-realistic, scalable, geo-referenced virtual 3D city model is useful for various kinds of applications such as for planning in navigation, tourism, disasters management, transportations, municipality, urban and environmental managements, real-estate industry. Thus this study will provide a good roadmap for geomatics community to create photo-realistic virtual 3D city model by using close range photogrammetry.
On the evaluation of photogrammetric methods for dense 3D surface reconstruction in a metrological context
Authors: Toschi I. , Capra A. , De Luca L. , Beraldin J.-A. , Cournoyer L.
Published: May 2014

Abstract. This paper discusses a methodology to evaluate the accuracy of recently developed image-based 3D modelling techniques. So far, the emergence of these novel methods has not been supported by the definition of an internationally recognized standard which is fundamental for user confidence and market growth. In order to provide an element of reflection and solution to the different communities involved in 3D imaging, a promising approach is presented in this paper for the assessment of both metric quality and limitations of an open-source suite of tools (Apero/MicMac), developed for the extraction of dense 3D point clouds from a set of unordered 2D images. The proposed procedural workflow is performed within a metrological context, through inter-comparisons with "reference" data acquired with two hemispherical laser scanners, one total station, and one laser tracker. The methodology is applied to two case studies, designed in order to analyse the software performances in dealing with both outdoor and environmentally controlled conditions, i.e. the main entrance of Cathédrale de la Major (Marseille, France) and a custom-made scene located at National Research Council of Canada 3D imaging Metrology Laboratory (Ottawa). Comparative data and accuracy evidence produced for both tests allow the study of some key factors affecting 3D model accuracy.
The documentation and reintegration of a lost past
Authors: Balletti C. , Brussa N. , Gottardi C. , Guerra F.
Published: May 2014

Abstract. The paper describes how new digital methodologies can be used within the field of Cultural Heritage, not only with the aim of documenting the actual state of an architecture but to review the past transformations it has undergone, conserving and representing these histories as well. Over the last few years, the methodologies of acquisition and integrated representation for 3D patrimony documentation have developed and consolidated considerably: the possibilities of the digital realm can augment the understanding and the valorisation of a monument. The specific case offered in the present paper, the Scuola Vecchia della Misericordia in Venice, is a significant example. It suggests not only the theme of the "no longer existing" regarding its façade, which has undergone evident modifications, but also the recontextualization of a number of decorative elements, such as the bas-reliefs which once marked the entrance and are today conserved in the Victoria and Albert Museum, London. The described experience shows how integrated methodology, from high resolution laser scanning and photogrammetric survey to 3d modelling, can develop a reliably virtual diachronical reconstruction from different sources of an historical building. Geomatic tools combined with computer graphics provide a better understanding of building history through the use historical documents, playing a paramount role in preserving and valorizing the cultural and environmental heritage.
True-orthophoto generation from UAV images: Implementation of a combined photogrammetric and computer vision approach
Authors: Barazzetti L. , Brumana R. , Oreni D. , Previtali M. , Roncoroni F.
Published: May 2014

Abstract. This paper presents a photogrammetric methodology for true-orthophoto generation with images acquired from UAV platforms. The method is an automated multistep workflow made up of three main parts: (i) image orientation through feature-based matching and collinearity equations / bundle block adjustment, (ii) dense matching with correlation techniques able to manage multiple images, and true-orthophoto mapping for 3D model texturing. It allows automated data processing of sparse blocks of convergent images in order to obtain a final true-orthophoto where problems such as self-occlusions, ghost effects, and multiple texture assignments are taken into consideration. The different algorithms are illustrated and discussed along with a real case study concerning the UAV flight over the Basilica di Santa Maria di Collemaggio in L'Aquila (Italy). The final result is a rigorous true-orthophoto used to inspect the roof of the Basilica, which was seriously damaged by the earthquake in 2009.
Fusion of 3D models derived from TLS and image-based techniques for CH enhanced documentation
Authors: Bastonero P. , Donadio E. , Chiabrando F. , Spanò A.
Published: May 2014

Abstract. Recognizing the various advantages offered by 3D new metric survey technologies in the Cultural Heritage documentation phase, this paper presents some tests of 3D model generation, using different methods, and their possible fusion. With the aim to define potentialities and problems deriving from integration or fusion of metric data acquired with different survey techniques, the elected test case is an outstanding Cultural Heritage item, presenting both widespread and specific complexities connected to the conservation of historical buildings. The site is the Staffarda Abbey, the most relevant evidence of medieval architecture in Piedmont. This application faced one of the most topical architectural issues consisting in the opportunity to study and analyze an object as a whole, from twice location of acquisition sensors, both the terrestrial and the aerial one. In particular, the work consists in the evaluation of chances deriving from a simple union or from the fusion of different 3D cloudmodels of the abbey, achieved by multi-sensor techniques. The aerial survey is based on a photogrammetric RPAS (Remotely piloted aircraft system) flight while the terrestrial acquisition have been fulfilled by laser scanning survey. Both techniques allowed to extract and process different point clouds and to generate consequent 3D continuous models which are characterized by different scale, that is to say different resolutions and diverse contents of details and precisions. Starting from these models, the proposed process, applied to a sample area of the building, aimed to test the generation of a unique 3Dmodel thorough a fusion of different sensor point clouds. Surely, the describing potential and the metric and thematic gains feasible by the final model exceeded those offered by the two detached models.
Towards A Knowledge Model Bridging Technologies And Applications In Cultural Heritage Documentation
Authors: Boochs F. , Trémeau A. , Murphy O. , Gerke M. , Lerma J.L. , Karmacharya A. , Karaszewski M.
Published: May 2014

Abstract. This paper documents the formulation of an international, interdisciplinary study, on a concerted European level, to prepare an innovative, reliable, independent and global knowledge base facilitating the use of today’s and future optical measuring techniques for the documentation of cultural heritage. Cultural heritage professionals, color engineers and scientists share similar goals for the documentation, curation, long-term preservation and representation of cultural heritage artifacts. Their focus is on accuracy in the digital capture and remediation of artefacts through a range of temporal, spatial and technical constraints. A shared vocabulary to interrogate these shared concerns will transform mutual understanding and facilitate an agreed movement forward in cultural heritage documentation here proposed in the work of the COST Action Color and Space in Cultural Heritage (COSCH). The goal is a model that captures the shared concerns of professionals for a standards-based solution with an organic Linked Data model. The knowledge representation proposed here invokes a GUI interface for non-expert users of capture technologies, facilitates, and formulates their engagement with key questions for the field.
Camera Calibration using the Damped Bundle Adjustment Toolbox
Authors: Börlin N. , Grussenmeyer P.
Published: May 2014

Abstract. Camera calibration is one of the fundamental photogrammetric tasks. The standard procedure is to apply an iterative adjustment to measurements of known control points. The iterative adjustment needs initial values of internal and external parameters. In this paper we investigate a procedure where only one parameter – the focal length is given a specific initial value. The procedure is validated using the freely available Damped Bundle Adjustment Toolbox on five calibration data sets using varying narrow- and wide-angle lenses. The results show that the Gauss-Newton-Armijo and Levenberg-Marquardt-Powell bundle adjustment methods implemented in the toolbox converge even if the initial values of the focal length are between 1/2 and 32 times the true focal length, even if the parameters are highly correlated. Standard statistical analysis methods in the toolbox enable manual selection of the lens distortion parameters to estimate, something not available in other camera calibration toolboxes. A standardised camera calibration procedure that does not require any information about the camera sensor or focal length is suggested based on the convergence results. The toolbox source and data sets used in this paper are available from the authors.