INVESTIGATION OF POINTNET FOR SEMANTIC SEGMENTATION OF LARGE-SCALE OUTDOOR POINT CLOUDS

Semantic segmentation of point clouds is indispensable for 3D scene understanding. Point clouds have credibility for capturing geometry of objects including shape, size, and orientation. Deep learning (DL) has been recognized as the most successful approach for image semantic segmentation. Applied to point clouds, performance of the many DL algorithms degrades, because point clouds are often sparse and have irregular data format. As a result, point clouds are regularly first transformed into voxel grids or image collections. PointNet was the first promising algorithm that feeds point clouds directly into the DL architecture. Although PointNet achieved remarkable performance on indoor point clouds, its performance has not been extensively studied in large-scale outdoor point clouds. So far, we know, no study on large-scale aerial point clouds investigates the sensitivity of the hyper-parameters used in the PointNet. This paper evaluates PointNet’s performance for semantic segmentation through three large-scale Airborne Laser Scanning (ALS) point clouds of urban environments. Reported results show that PointNet has potential in large-scale outdoor scene semantic segmentation. A remarkable limitation of PointNet is that it does not consider local structure induced by the metric space made by its local neighbors. Experiments exhibit PointNet is expressively sensitive to the hyper-parameters like batch-size, block partition and the number of points in a block. For an ALS dataset, we get significant difference between overall accuracies of 67.5% and 72.8%, for the block sizes of 5m×5m and 10m×10m, respectively. Results also discover that the performance of PointNet depends on the selection of input vectors

ESA's Ice Sheets CCI: validation and inter-comparison of surface elevation changes derived from laser and radar altimetry over Jakobshavn Isbræ, Greenland – Round Robin results

In order to increase the understanding of the changing climate, the European Space Agency has launched the Climate Change Initiative (ESA CCI), a program which joins scientists and space agencies into 13 projects either affecting or affected by the concurrent changes. This work is part of the Ice Sheets CCI and four parameters are to be determined for the Greenland Ice Sheet (GrIS), each resulting in a dataset made available to the public: Surface Elevation Changes (SEC), surface velocities, grounding line locations, and calving front locations. All CCI projects have completed a so-called Round Robin exercise in which the scientific community was asked to provide their best estimate of the sought parameters as well as a feedback sheet describing their work. By inter-comparing and validating the results, obtained from research institutions world-wide, it is possible to develop the most optimal method for determining each parameter. This work describes the SEC Round Robin and the subsequent conclusions leading to the creation of a method for determining GrIS SEC values. The participants used either Envisat radar or ICESat laser altimetry over Jakobshavn Isbræ drainage basin, and the submissions led to inter-comparisons of radar vs. altimetry as well as cross-over vs. repeat-track analyses. Due to the high accuracy of the former and the high spatial resolution of the latter, a method, which combines the two techniques will provide the most accurate SEC estimates. The data supporting the final GrIS analysis stem from the radar altimeters on-board Envisat, ERS-1 and ERS-2. The accuracy of laser data exceeds that of radar altimetry; the Round Robin analysis has, however, proven the latter equally capable of dealing with surface topography thereby making such data applicable in SEC analyses extending all the way from the interior ice sheet to margin regions. This shows good potential for a~future inclusion of ESA CryoSat-2 and Sentinel-3 radar data in the analysis, and thus for obtaining reliable SEC estimates throughout the entire GrIS

HIGH-FREQUENCY 3D GEOMORPHIC OBSERVATION USING HOURLY TERRESTRIAL LASER SCANNING DATA OF A SANDY BEACH

Geomorphic processes occur spatially variable and at varying magnitudes, frequencies and velocities, which poses a great challenge to current methods of topographic change analysis. For the quantification of surface change, permanent terrestrial laser scanning (TLS) can generate time series of 3D point clouds at high temporal and spatial resolution. We investigate how the temporal interval influences volume change observed on a sandy beach regarding the temporal detail of the change process and the total volume budget, on which accretion and erosion counteract. We use an hourly time series of TLS point clouds acquired over six weeks in Kijkduin, the Netherlands. A raster-based approach of elevation differencing provides the volume change over time per square meter. We compare the hourly analysis to results of a three- and six-week observation period. For the larger period, a volume increase of 0.3 m3/ m2 is missed on a forming sand bar before it disappears, which corresponds to half its volume. Generally, a strong relationship is shown between observation interval and observed volume change. An increase from weekly to daily observations leads to a five times larger volume change quantified in total. Another important finding is a temporally variable measurement uncertainty in the 3D time series, which follows the daily course of air temperature. Further experiments are required to fully understand the effect of atmospheric conditions on high-frequency TLS acquisition in beach environments. Continued research of 4D geospatial analysis methods will enable automatic identification of dynamic change and improve the understanding of geomorphic processes

A review of the use of terrestrial laser scanning application for change detection and deformation monitoring of structures

Change detection and deformation monitoring is an active area of research within the field of engineering surveying as well as overlapping areas such as structural and civil engineering. The application of Terrestrial Laser Scanning (TLS) techniques for change detection and deformation monitoring of concrete structures has increased over the years as illustrated in the past studies. This paper presents a review of literature on TLS application in the monitoring of structures and discusses registration and georeferencing of TLS point cloud data as a critical issue in the process chain of accurate deformation analysis. Past TLS research work has shown some trends in addressing issues such as accurate registration and georeferencing of the scans and the need of a stable reference frame, TLS error modelling and reduction, point cloud processing techniques for deformation analysis, scanner calibration issues and assessing the potential of TLS in detecting sub-centimetre and millimetre deformations. However, several issues are still open to investigation as far as TLS is concerned in change detection and deformation monitoring studies such as rigorous and efficient workflow methodology of point cloud processing for change detection and deformation analysis, incorporation of measurement geometry in deformation measurements of high-rise structures, design of data acquisition and quality assessment for precise measurements and modelling the environmental effects on the performance of laser scanning. Even though some studies have attempted to address these issues, some gaps exist as information is still limited. Some methods reviewed in the case studies have been applied in landslide monitoring and they seem promising to be applied in engineering surveying to monitor structures. Hence the proposal of a three-stage process model for deformation analysis is presented. Furthermore, with technological advancements new TLS instruments with better accuracy are being developed necessitating more research for precise measurements in the monitoring of structures

Recognising Victimhood: Lessons from the International Criminal Court and Mass Claim Programmes for the Compensation Procedure Parallel to the Trial of International Crimes in the Netherlands

In the Netherlands, the Dutch criminal court in The Hague (hereinafter: ‘Netherlands International Crimes Court’ or ‘NIC court’) is assigned to try international crimes, and to provide compensation to victims of such crimes. Whereas it has specific criminal laws at its disposal to try international crimes, it applies ‘regular’ Dutch civil law to assess claims for compensation. Yet compensation for international crimes entails challenges that are quite different from domestic crimes: international crimes are normally committed against a large number of victims, and frequently result in bodily harm. This article argues that the NIC court will most likely rule a large number of claims for compensation inadmissible, as a consequence of which victims cannot benefit from the advantages inherent in the award of compensation within the criminal process. It then explores the adjudicative and reparatory standards that the International Criminal Court and mass claim programmes have applied to simplify both the adjudication of a large number of claims, and the calculation of a large number of instances of bodily damage. It is submitted that adoption by the NIC court of international reparatory standards could facilitate the assessment of a large number of civil claims within the criminal process, without prejudice to the legitimate interests of the defendant for an adequate procedure. However, these standards require the NIC court to strike a new balance between tailor-made compensation and symbolic compensation, and thereby between corrective justice and restorative justice

Development and Function of Immune Cells in an Adolescent Patient with a Deficiency in the Interleukin-10 Receptor

OBJECTIVE:: Monogenic defects in the interleukin-10 (IL-10) pathway are extremely rare and cause infantile-onset inflammatory bowel disease (IBD)-like pathology. Understanding how immune responses are dysregulated in monogenic IBD-like diseases can provide valuable insight in “classical” IBD pathogenesis. Here, we studied long-term immune cell development and function in an adolescent IL-10 receptor (IL10RA)-deficient patient who presented in infancy with severe colitis and fistulizing perianal disease and is currently treated with immune suppressants. METHODS:: Biomaterial was collected from the IL10RA-deficient patient, pediatric IBD patients and healthy controls. The frequency and phenotype of immune cells were determined in peripheral blood and intestinal biopsies by flow cytometry and immunohistochemistry. Functional changes in monocyte-derived dendritic cells and T cells were assessed by in vitro activation assays. RESULTS:: The IL10RA-deficient immune system developed normally with respect to numbers and phenotype of circulating immune cells. Despite normal co-stimulatory molecule expression, bacterial lipopolysaccharide-stimulated monocyte-derived dendritic cells from the IL10RA-deficient patient released increased amounts of TNFα compared to healthy controls. Upon T-cell receptor ligation, IL10RA-deficient peripheral blood mononuclear cells released increased amounts of T cell cytokines IFNγ and IL-17 agreeing with high numbers of T-bet and IL-17 cells in intestinal biopsies taken at disease onset. In vitro, the immunosuppressive drug thalidomide used to treat the patient decreased peripheral blood mononuclear cell-derived TNFα production. CONCLUSIONS:: With time and during immunosuppressive treatment the IL10RA- deficient immune system develops relatively normally. Upon activation, IL-10 is crucial for controlling excessive inflammatory cytokine release by dendritic cells and preventing IFNγ and IL-17-mediated T-cell responses

Alcohol Facilitates CD1d Loading, Subsequent Activation of NKT Cells, and Reduces the Incidence of Diabetes in NOD Mice

Background: Ethanol ('alcohol') is a partly hydrophobic detergent that may affect the accessibility of glycolipids thereby influencing immunological effects of these molecules. Methods: The study included cellular in vitro tests using α-galactosylceramide (αGalCer), and in vivo NOD mice experiments detecting diabetes incidence and performing behavioural and bacterial analyses. Results: Alcohol in concentrations from 0.6% to 2.5% increased IL-2 production from NKT cells stimulated with αGalCer by 60% (p<0.05). CD1d expressed on HeLa cells contained significantly increasing amounts of αGalCer with increasing concentrations of alcohol, suggesting that alcohol facilitated the passive loading of αGalCer to CD1d. NOD mice were found to tolerate 5% ethanol in their drinking water without signs of impairment in liver function. Giving this treatment, the diabetes incidence declined significantly. Higher numbers of CD3+CD49b+ NKT cells were found in spleen and liver of the alcohol treated compared to the control mice (p<0.05), whereas the amount of CD4+Foxp3+ regulator T cells did not differ. Increased concentrations of IFN-γ were detected in 24-hour blood samples of alcohol treated mice. Behavioural studies showed no change in attitude of the ethanol-consuming mice, and bacterial composition of caecum samples was not affected by alcohol, disqualifying these as protective mechanisms. Conclusion: Alcohol facilitates the uptake of glycolipids and the stimulation of NKT cells, which are known to counteract Type 1 diabetes development. We propose that this is the acting mechanism by which treatment with alcohol reduces the incidence of diabetes in NOD mice. This is corroborated by epidemiology showing beneficial effect of alcohol to reduce the severity of atherosclerosis and related diseases

Mrp1 is involved in lipid presentation and iNKT cell activation by Streptococcus pneumoniae

The CD1d pathway present lipid antigens resulting in the activation of iNKT cells but the complete pathway remains to be fully elucidated. Here, Chandra et al. use an siRNA screen and identify Mrp1 as crucial for CD1d lipid presentation and activation of iNKT in the context of Streptococcus pneumoniae infection