Semi-automatic Procedures Research Articles

DIRECT PHOTOGRAMMETRY USING UAV: TESTS AND FIRST RESULTS

Abstract. In recent years, the quality of high resolution acquisition platforms for geomatic applications has decidedly increased, especially in the performance of the sensors devoted to image acquisition. The small size of these new sensors combined with the increase in resolution allows them to be easily mounted onto Unmanned Aerial Vehicles (UAVs); in particular, calibrated, very-high-resolution digital cameras for photogrammetric purposes such as digital terrain model (DTM) and digital surface model (DSM) extraction, orthophotos, and map realization have been used. In this case, the UAV performance allows a high quality product to be obtained, considering the pixel size and the accuracy of the DTM/DSM which could be obtained with automatic procedures. Several navigation sensors (GPS/GNSS and IMU-MEMS) are embedded into UAVs in order to realize autonomous flight. The quality of these sensors, in terms of accuracy, depends on the model of UAV and its purpose. The navigation solution (position and attitude) is estimated by the internal UAV sensor and can be employed to directly georeference the images, in order to produce an quick and easy description and analysis of the overlooked area. This is a good condition for semi-automatic procedures using a bundle-block photogrammetric approach. But is it possible to realize a direct photogrammetry? And what are the limits? Several tests were carried out over different areas and in different conditions using three different UAVs belonging to the Geomatics group of the Politecnico di Torino. In this paper, an investigation of the limits of some commercial UAVs is reported, defining a dedicated procedure to valuate their performance, especially considering the use of UAVs for direct photogrammetry.

A New Algorithm for Reliable and General NMR Resonance Assignment

The new FLYA automated resonance assignment algorithm determines NMR chemical shift assignments on the basis of peak lists from any combination of multidimensional through-bond or through-space NMR experiments for proteins. Backbone and side-chain assignments can be determined. All experimental data are used simultaneously, thereby exploiting optimally the redundancy present in the input peak lists and circumventing potential pitfalls of assignment strategies in which results obtained in a given step remain fixed input data for subsequent steps. Instead of prescribing a specific assignment strategy, the FLYA resonance assignment algorithm requires only experimental peak lists and the primary structure of the protein, from which the peaks expected in a given spectrum can be generated by applying a set of rules, defined in a straightforward way by specifying through-bond or through-space magnetization transfer pathways. The algorithm determines the resonance assignment by finding an optimal mapping between the set of expected peaks that are assigned by definition but have unknown positions and the set of measured peaks in the input peak lists that are initially unassigned but have a known position in the spectrum. Using peak lists obtained by purely automated peak picking from the experimental spectra of three proteins, FLYA assigned correctly 96-99% of the backbone and 90-91% of all resonances that could be assigned manually. Systematic studies quantified the impact of various factors on the assignment accuracy, namely the extent of missing real peaks and the amount of additional artifact peaks in the input peak lists, as well as the accuracy of the peak positions. Comparing the resonance assignments from FLYA with those obtained from two other existing algorithms showed that using identical experimental input data these other algorithms yielded significantly (40-142%) more erroneous assignments than FLYA. The FLYA resonance assignment algorithm thus has the reliability and flexibility to replace most manual and semi-automatic assignment procedures for NMR studies of proteins.

Digital parameterization of apple fruit size, shape and surface spottiness

To reach fruit market standards, quality evaluation has to be performed. Computer assisted fruit image analysis represents a technique, which offers a variety of automatic and semi-automatic procedures that can be used in combination with classic evaluation methods. To achieve this goal, a digital parameterization method for single apple fruit (Malus domestica) size, shape and surface spottiness has been recently developed. The appropriate mathematical procedures, defining the criteria for the fruit quality parameterization, are also defined and tested. The concept of the method, as well as the initial testing results, is presented in this paper. Basically, the technique combines analysis of apple fruit 256 gray-scale level images and parameterization algorithm of fruit quality. The former is based on digital pattern recognition method (DPR), and the latter employs linear fitting and numerical integration of DPR output data. This way, accurate parameterization of the fruit size, shape and surface spottiness, as well as the reliable fruit sorting according to the product quality, is enabled. Key words: Apple fruit, computer vision, quality criteria, mathematical procedure, digital pattern recognition.

Dune cliff erosion and beach width change at the northern and southern spits of Sylt detected with multi-temporal Lidar

Abstract Since the end of Pleistocene the west coast of Sylt (Germany) has been a very dynamic geomorphic system. At present especially the northern and southern spits (Ellenbogen and Hornum-Odde) are changing rapidly. Airborne Lidar (light detection and ranging) has been used since 1999 to measure the coast inter- and intra-annually. The aim of this study is to exploit the potential of the laser data to describe and explain the changes at the west coast of the northern and southern spits of Sylt. Lidar accuracy verification approves the value of the data. After offset correction a horizontal difference of 0.5 m and a maximal vertical difference of 0.12 m remain. Dune cliff changes are monitored by applying semi-automatic breakline extraction procedures to multi-temporal Lidar data. The breakline extraction is based on filter methods derived from digital image analysis. Furthermore beach width changes are analyzed. At the Hornum-Odde and at the Ellenbogen a maximal dune retreat of 140 m and 70 m respectively was measured. Different annual as well as seasonal coastal change patterns could be revealed. Dunes are only eroded during winter due to storm surges, while the beach width varies during all seasons due to generally high shoreline dynamics. Beach width influences dune cliff erosion differently at the two study sites. At the west coast of the northern spit backshore dunes are eroded suddenly after an enduring period of general beach width decrease. Afterwards beach width increases and cliff position stabilizes again. Beach nourishment can protect the dunes due to beach width preservation. At the west coast of the southern spit local interactions dominate. Expanded beach segments cause lee effects and hence dune erosion. Different beach nourishment projects could not avoid dune erosion.

Spike Sorting by Stochastic Simulation

The decomposition of multiunit signals consists of the restoration of spike trains and action potentials in neural or muscular recordings. Because of the complexity of automatic decomposition, semiautomatic procedures are sometimes chosen. The main difficulty in automatic decomposition is the resolution of temporally overlapped potentials. In a previous study , we proposed a Bayesian model coupled with a maximum a posteriori (MAP) estimator for fully automatic decomposition of multiunit recordings and we showed applications to intramuscular EMG signals. In this study, we propose a more complex signal model that includes the variability in amplitude of each unit potential. Moreover, we propose the Markov Chain Monte Carlo (MCMC) simulation and a Bayesian minimum mean square error (MMSE) estimator by averaging on samples that converge in distribution to the joint posterior law. We prove the convergence property of this approach mathematically and we test the method representatively on intramuscular multiunit recordings. The results showed that its average accuracy in spike identification is greater than 90% for intramuscular signals with up to 8 concurrently active units. In addition to intramuscular signals, the method can be applied for spike sorting of other types of multiunit recordings.

Semantics-aware matching strategy (SAMS) for the Ontology meDiated Data Integration (ODDI)

Data integration systems are used to integrate heterogeneous data sources in a single view. Recent work on business intelligence highlights the need of on-time, reliable and sound data access systems relying on methods based on semi-automatic procedures. A crucial factor for any semi-automatic algorithm is that of the matching strategy. Different categories of matching operators carry different semantics. For this reason, combining them into a single strategy is a non-trivial process that has to take into account a variety of options. This paper presents SAMS, a matching strategy based on a semantics-aware categorisation of matching operators that allows to group similar attributes on a semantically-rich form.

Coupled urban wind flow and indoor natural ventilation modelling on a high-resolution grid: A case study for the Amsterdam ArenA stadium

Wind flow in urban environments is an important factor governing the dispersion of heat and pollutants from streets, squares and buildings. This paper presents a coupled CFD modelling approach for urban wind flow and indoor natural ventilation. A specific procedure is used to efficiently and simultaneously generate the geometry and the high-resolution body-fitted grid for both the outdoor and indoor environment. This procedure allows modelling complex geometries with full control over grid quality and grid resolution, contrary to standard semi-automatic unstructured grid generation procedures. It also provides a way to easily implement various changes in the model geometry and grid for parametric studies. As a case study, a parametric analysis of natural ventilation is performed for the geometrically complex Amsterdam ArenA stadium in the Netherlands. The turbulent wind flow and temperature distribution around and inside the stadium are solved with the 3D steady Reynolds-averaged Navier–Stokes equations. Special attention is given to CFD solution verification and validation. It is shown that small geometrical modifications can increase the ventilation rate by up to 43%. The coupled modelling approach and grid generation procedure presented in this paper can be used similarly for future studies of wind flow and related processes in complex urban environments.

Perspectives of hyperspectral data application for vegetation studies

In this paper the possibilities of hyperspectral data processing are investigated regarding the application of these images in natural and ecological applications. A short overview is given of the available methods for interpretation purposes and special attention is paid on how the unique properties of hyperspectral data are affecting the choice of suitable methods for processing. Further steps required for developing a set of application dependent image processing chain is also addressed with the aim of applying both spatial and spectral information contained in datasets. A broad identification of possible processing chain is discussed with the aim of developing more standardised and application suited way of processing of the large data volumes. Automatic or semi-automatic procedures are proposed and key steps are identified that could lead to high quality mapping products by means of digital signal processing. This work is to be continued with testing the performance at different stages of interpretation while different techniques are used, and a document is to be supplied through HYPER-I-NET with the collection of results and application specific suggestions regarding hyperspectral data application for vegetation monitoring purposes.

Unsupervised Bayesian Decomposition of Multiunit EMG Recordings Using Tabu Search

Intramuscular electromyography (EMG) signals are usually decomposed with semiautomatic procedures that involve the interaction with an expert operator. In this paper, a Bayesian statistical model and a maximum a posteriori (MAP) estimator are used to solve the problem of multiunit EMG decomposition in a fully automatic way. The MAP estimation exploits both the likelihood of the reconstructed EMG signal and some physiological constraints, such as the discharge pattern regularity and the refractory period of muscle fibers, as prior information integrated in a Bayesian framework. A Tabu search is proposed to efficiently tackle the nondeterministic polynomial-time-hard problem of optimization w.r.t the motor unit discharge patterns. The method is fully automatic and was tested on simulated and experimental EMG signals. Compared with the semiautomatic decomposition performed by an expert operator, the proposed method resulted in an accuracy of 90.0% +/- 3.8% when decomposing single-channel intramuscular EMG signals recorded from the abductor digiti minimi muscle at contraction forces of 5% and 10% of the maximal force. The method can also be applied to the automatic identification and classification of spikes from other neural recordings.

Hyperspectral data processing chain development perspectives for vegetation studies

In this paper the possibilities of hyperspectral data processing is investigated regarding to the application of these images in natural and ecological applications. A short overview is given of the available methods for interpretation purposes and special attention is paid on how the unique properties of hyperspectral data are affecting the choice from available methods for data processing. A broad identification of possible processing chain is discussed with the aim of developing more modular and application driven way of processing of the large data volumes. Automatic or semi-automatic procedures are proposed and key steps are to be identified that could lead to high quality mapping products by means of digital signal processing. Some experimental results are published and the broad methodology is presented that is aimed to use for identify data processing chain for vegetation mapping purposes. This work is to be continued with testing the performance at different stages of interpretation while different techniques are used. Furthermore over the HYPER-I-NET research network a document is to be supplied with the collection of results and application specific suggestions regarding to hyperspectral data processing for vegetation monitoring purposes.

Prerequisites for a Cc/ Cs-corrected ultrahigh-resolution TEM

After the introduction of a corrector to compensate for the spherical aberration of a TEM and the acceptance of this new instrumentation for high-resolution CTEM (conventional transmission electron microscope) and STEM (scanning transmission electron microscope) by the electron microscopy community, a demand for even higher resolution far below 1 Å has emerged. As a consequence several projects around the world have been launched to make these new instruments available and to further push the resolution limits down toward fractions of 1 Å. For this purpose the so-called TEAM (transmission electron aberration-corrected microscope) has been initiated and is currently under development. With the present paper we give a detailed assessment of the stability required for the base instrument and the electric stability, the manufacturing precision, and feasible semi-automatic alignment procedures for a novel C c/ C s-corrector in order to achieve aberration-free imaging with an information limit of 0.5 Å at an acceleration voltage of 200 kV according to the goals for the first TEAM instrument. This new aberration corrector, a so-called Achroplanat, in combination with a very stable high-resolution TEM leads to an imaging device with unprecedented resolving power and imaging properties.

Reconstruction of ripped-up documents using fragment stack analysis procedures

Reconstruction of ripped-up documents can be a very time-consuming task for forensic experts. Currently, this task is often carried out using various homespun or loosely defined procedures. Under the main assumption that a (partially) ordered set of fragments can be recovered, we propose and discuss a more formal analysis methodology for this type of reconstruction problem. We discuss several complications that can occur in real-life problems and illustrate the efficiency of the proposed methods. Although several avenues for further research remain, we show that the proposed approach offers both a better understanding of the problem, as well as important strategies for devising very fast manual and semi-automatic fragment reassembly procedures.

Module production for the CMS Tracker: Problems and achieved quality

The construction of the CMS Inner Tracker is nearing completion. The various components are being mounted on the large structures and by the end of 2006 the tracker assembly will be finished at CERN. The basic elements of the strip tracker are the silicon sensor modules. In total about 15,000 modules of various geometries have been built by a large collaboration of institutes. This paper will explain the design and the semi-automatic assembly procedures. The major problems which appeared during this production are discussed. The final section gives an overview of the obtained results.

Error rates in buccal-dental microwear quantification using scanning electron microscopy

Dental microwear, usually analyzed using scanning electron microscopy (SEM) techniques, is a good indicator of the abrasive potential of past human population diets. Scanning electron microscopy secondary electrons provide excellent images of dental enamel relief for characterizing striation density, average length, and orientation. However, methodological standardization is required for interobserver comparisons since semiautomatic counting procedures are still used for micrograph characterization. The analysis of normally distributed variables allows the characterization of small interpopulation differences. However, the interobserver error rates associated with SEM experience and the degree of expertise in measuring striations are critical to population dietary interpretation. The interobserver comparisons made here clearly indicate that the precision of SEM buccal microwear measurements depends heavily on variable definition and the researcher's expertise. Moreover, error rates are not the only concern for dental microwear research. Low error rates do not guarantee that all researchers are measuring the same magnitudes of the variables considered. The results obtained show that researchers tend to maintain high intrapopulation homogeneity and low measurement error rates, whereas significant interobserver differences appear. Such differences are due to a differential interpretation of SEM microwear features and variable definitions that require detailed and precise agreement among researchers. The substitution of semiautomatic with fully automated procedures will completely avoid interobserver error rate differences.

Troubles cognitifs et sclérose en plaques rémittente : intérêt de leur détection précoce: Corrélations anatomo-fonctionnelles et suivi longitudinal

Cognitive impairment is frequent in relapsing remitting Multiple Sclerosis and is often diagnosed after disruption of occupational and social relations.We studied at baseline a homogeneous population of 32 RRMS patients, diagnosed for less than 5 years, with spontaneous memory complaints, and 20 controls. Sixteen patients were followed for 2 years, combining physical examination, neuropsychological tests, and brain MRI. Neuropsychological tests used evaluated memory capacities, attentional capacities, executive functions, language, and visuo-constructive praxis. Lesion load on brain MRI was measured with semi-automatic segmentation procedures and manual control.Eighty percent of patients presented cognitive impairment, and this proportion was higher than that found in the literature. These disorders were more marked for verbal episodic memory, attention, and executive functions. Patients with brain MRI that initially fulfilled the Barkhof criteria and those with callous lesions had more memory disorders. No link between global T1 and T2 lesion loads and neuropsychological scores was found. A statistical link between posterior fossa lesions and attentional disorders was shown. In the longitudinal follow-up, patients had better performances in memory and attentional domains, and a lower number of cognitive domains with dysfunction for each patient. This improvement on neuropsychological tests, whereas EDSS levels were stable, underlined a possible test-retest effect.During the initial phase of the disease, most of the relapsing remitting patients present a mild cognitive impairment. Early detection, therapeutic propositions, and recognition of disorders are necessary.

Reconstruction of the recent changes of a debris-covered glacier (Brenva Glacier, Mont Blanc Massif, Italy) using indirect sources: Methods, results and validation

A quantitative analysis was performed with the aim of identifying changes in the volume and thickness of the Brenva Glacier tongue (Mont Blanc Massif, Italy) in the second half of the 20th century. This analysis was based on the comparison of digital elevation models (DEMs) derived from historical records, specifically maps (1959, 1971, 1983, 2003) and photogrammetric surveys (1991, 1997). The DEMs were generated by means of a digital photogrammetric workstation, with semi-automatic and automatic procedures. Problems relating to the identification of the control points in the photos had to be resolved in order to define the external orientation. An unconventional photogrammetric methodology, based on the identification of homologous points in zones considered outside of the glacier area, was adopted to insert the surveys into a single reference system. Furthermore, along with the photogrammetric data, DEMs derived from digitized historical maps were generated and compared to define changes in the geometry of the glacier tongue. The results indicated a positive long-term glacier tongue balance. In fact, between 1959 and 2003, there was an increase of 22.6 × 10 6 m 3, equal to an average thickness of ca.+ 34 m (+ 0.7 m a − 1 w.e.). Validation of the data obtained from comparison of the DEMs and the reliability of the results were discussed as well.

Real-Time motion control software for a micromanipulator

This paper will present a motion control software for 8 micromanipulator named MANiPEN. This manipulator has been developed for biomedical applications that require manipulation of biological cells. With the software. a human useris ablc to pcrform frcehand motion control of the manipulator. In addition, it is possible to execute semiautomatic procedures that cxeeute 8 mieroinjeetion of substances into a cell and an aspiration of a cell into the capillary of the micromanipulator. Highprecision requirements of the micromanipulator cause strict requirements for the software. A key issue is the determinism of timing of control operations. Therefore. the software has been implemented on top of a real-time Linux operating system executing in a stardard PC.

Reverse engineering of free-form surfaces: A methodology for threshold definition in selective sampling

Reverse engineering is a technique used during the project phase of a new product, which makes it possible to trace, in terms of mathematical expressions, the geometrical features of a given physical model. Scientific literature presents many different approaches to reverse engineering. Great part of those are based on the analysis of point clouds acquired through coordinate measuring devices, such as, for example, Coordinate Measuring Machines (CMMs), Optical Scanners or Interferometric Systems. Referring to this kind of approach, a common problem is to individuate the surface zones, which present sensible variations of curvature. Many algorithms, commonly implemented on commercial software through semi-automatic procedures, are already based on this method. In these cases the local curvature variation of the measured surfaces is analyzed by defining a threshold over which it is necessary to perform a deeper scansion of the surface zones. However, most of the problems are related to the definition of an appropriate value for the threshold level. In the present paper a methodology for the definition of the threshold value based on the measurement system uncertainty is described. In the current description the method is applied to an elementary algorithm for curvature definition, but it could be extended to any other kind of more complicated approach. Furthermore, it will be demonstrated that this new methodology is simple to apply and can be easily automated in commercial software for points selective sampling in industrial reverse engineering applications. In the end a practical example is described in order to give an experimental validation of the method.

Development of a focused charged particle microbeam for the irradiation of individual cells

An irradiation facility, able to expose cellular and subcellular targets to a precise number of particles, has been developed at CENBG for applications in radiobiology. The development of this facility was based on an existing horizontal focused microbeam developed in the early 90’s for material analysis. The focusing properties of the line allow the delivering of proton or alpha particle beams in the 1–3.5MeV energy range with a spatial resolution down to about 1μm under vacuum. For irradiation of living cells, a removable stage has been developed to extract the beam into air while preserving the analytical capabilities of the microbeam line under vacuum. This stage includes a high resolution epifluorescence microscope for online visualization of the cells and a motorized stage for cell positioning. Single particle control is ensured by a fast electrostatic deflector triggered by the signal induced by the particles through a transmission detector just before reaching the target. A dedicated software, based on an object-oriented architecture, has been designed to control the entire experiment. This includes semiautomatic calibration procedures (necessary to achieve the micron precision) and semiautomatic irradiation procedures used for targeting a large number of individual cells. In air irradiation of solid track detectors has permitted us to estimate that 99.5% of the particles are delivered on the target at a distance lower than 5μm from the beam center when an alpha particles beam is used. The targeting precision of the overall irradiation procedure, which reflects the alignment precision of the beam center with the target center, has been estimated to be within ±2μm. First experiments involving cells in culture have permitted to estimate an irradiation rate of 2000 cells per hour. This article presents the overall experimental facility and the tests performed for its validation for the irradiation of individual cells in their culture medium.

Responding to the Information Challenges

Presents comments on selected findings of the Business Information Resources Survey 2004 in light of the experiences of D&B (Dun & Bradstreet) and focusing on the survey’s conclusions regarding the challenges facing information professionals as they attempt to provide quality services for their users and the worrying trend for corporate libraries to reduce their spending on information in response to the toughening of the business climate. Considers why it is that budget holders in UK industry are still not convinced that spending money on quality information and knowledge management is a sound investment, capable of yielding increased revenues and reduced costs. The information professional is faced with the twin challenges of demonstrating the value of the company information service, and securing high quality information services with very limited resources. The challenge for the information provider includes: providing high quality, reliable data; making that data available through relevant,user friendly interfaces; delivering new value added services; helping to provide information about the return to be gained by investing in such services; and making such services available in a cost effective manner. D&B employs a strategy for developing a single information source for global company data that involves the use of multiple sources of global information. Describes some of the automatic and semiautomatic procedures used by D&B to construct their databases and ensure the timeliness and quality of the data.