362 research outputs found
Density-Adaptive and Geometry-Aware Registration of TLS Point Clouds Based on Coherent Point Drift
No full textProbabilistic registration algorithms [e.g., coherent point drift, (CPD)] provide effective solutions for point cloud alignment. However, using the original CPD algorithm for automatic registration of terrestrial laser scanner (TLS) point clouds is highly challenging because of density variations caused by scanning acquisition geometry. In this letter, we propose a new global registration method, introducing the use of the CPD framework for TLS point clouds. We first consider the measurement geometry and the intrinsic characteristics of the scene to simplify points. In addition to the Euclidean distance, we incorporate geometric information as well as structural constraints in the probabilistic model to optimize the so-called matching probability matrix. Among the structural constraints, we use a spectral graph to measure the structural similarity between matches at each iteration. The method is tested on three data sets collected by different TLS scanners. Experimental results demonstrate that the proposed method is robust to density variations and can decrease iterations effectively. The average registration errors of the three data sets are 0.05, 0.12, and 0.08 m, respectively. It is also shown that our registration framework is superior to the state-of-the-art methods in terms of both registration errors and efficiency. The experiments demonstrate the effectiveness and efficiency of the proposed probabilistic global registration.Accepted author manuscriptOptical and Laser Remote Sensin
Terrestrial Laser Scanning (TLS) over volcanic areas: experiments on Vesuvius, Stromboli and Vulcano (Italy)
No full textGeomorphological changes of areas affected by crustal deformation, eruptive events, gravitative instabilities, land-
slide and glacier evolution, and other phenomena, can be detected and quantified using high-accuracy digital sur-
face models. The comparison between multitemporal models provides a space-time description of geophysical
processes, and can be used to estimate deformation patterns, displacements, surface variations, volumes involved
in mass movements, and other physical features. Several techniques, including GPS kinematic methodology, digi-
tal aerial and terrestrial photogrammetry, airborne and terrestrial laser scanning, satellite-based and ground-based
interferometric radar and optical satellite imagery systems, are suitable surveying methods that provide appropriate
spatial resolution.
Terrestrial Laser Scanning (TLS) allows an accurate and cost-effective representation of the topographical details
of the observed surface. For this reason, TLS is currently used in geologic survey, engineering practice, cultural
heritage, and mobile mapping. Besides the geometric data, the point cloud provided by a TLS observation con-
tains radiometric information, i.e. the intensity of the received pulses, that can be used for classification purposes.
Moreover, some instruments are equipped with a calibrated camera to add RGB color data to the intensity data.
Since a TLS survey, including the corresponding data processing and analysis, can be carried out in relatively short
time, an operational procedure can be planned and executed. The TLS and other remote sensing techniques, like
digital photogrammetry, can be integrated to profit from the strength of each single technique and overcome the
corresponding weakness, leading to a better modeling of the observed system.
We show the results of observations on three Italian volcanoes by using a TLS recently implemented in the moni-
toring system of the INGV. The most complete set has been acquired on Mt. Vesuvius crater in May 2005, October
2006 and June 2009. The whole crater was measured with several overlapped scans and the corresponding digital
surface models were generated and registered into the UTM-WGS84 reference frame. The comparison between
the models leads to an evaluation of the occurred changes. The deformation maps showed a progressive mass loss
due to rock-falls in an area of about 5000 m2 with a corresponding accumulation at the bottom of the crater. The
volume loss which occurred from 2005 to 2009, was computed by subtraction of volumes defined with respect
to reference planes parallel to the caldera walls and was estimated to be 20300 m3. Some results were also in-
terpreted on the basis of micro-seismic and meteorological data in order to plan a monitoring technique where
seismic signals related to rock-fall and/or signals of intense rainfalls are used as alarms for fast TLS surveys able
to characterize the corresponding changes of the caldera walls. The proposed methodology, in particular the simple
but effective approach used in the estimation of volume uncertainties, can be applied to each rock slope instability
phenomenon, regardless to the particular environment.
Two measurements were carried out at Vulcano in April 2009, by surveying the whole “La Fossa” crater and
the “La Forgia” unstable slope, and in April 2010, by re-surveying again the “La Forgia” slope. All measurements
were acquired with several overlapped scans. The comparison between the two measurements at “La Forgia” shows
small change in the morphology that will be further investigated by new measurements; new measures will also be
carried out to image again the “La Fossa” crater.
Measurements at Stromboli were aimed at testing the capability of the technique in very difficult surveying con-
ditions: the 2007 lava fan in the Sciara del Fuoco, an inaccessible and unstable area of the Stromboli volcano. In
such a condition, TLS observes the fan only with high incidence angles and from distances longer than La Fossa
case. In addition, the lava fan consists in black porous lavas, characterized by a bad reflectivity.PublishedVienna, Austria 3–8 April 20111.3. TTC - Sorveglianza geodetica delle aree vulcaniche attiveope
Terrestrial Laser Scanning (TLS) over volcanic areas: experiments on Vesuvius, Stromboli and Vulcano (Italy)
No full textGeomorphological changes of areas affected by crustal deformation, eruptive events, gravitative instabilities, land-
slide and glacier evolution, and other phenomena, can be detected and quantified using high-accuracy digital sur-
face models. The comparison between multitemporal models provides a space-time description of geophysical
processes, and can be used to estimate deformation patterns, displacements, surface variations, volumes involved
in mass movements, and other physical features. Several techniques, including GPS kinematic methodology, digi-
tal aerial and terrestrial photogrammetry, airborne and terrestrial laser scanning, satellite-based and ground-based
interferometric radar and optical satellite imagery systems, are suitable surveying methods that provide appropriate
spatial resolution.
Terrestrial Laser Scanning (TLS) allows an accurate and cost-effective representation of the topographical details
of the observed surface. For this reason, TLS is currently used in geologic survey, engineering practice, cultural
heritage, and mobile mapping. Besides the geometric data, the point cloud provided by a TLS observation con-
tains radiometric information, i.e. the intensity of the received pulses, that can be used for classification purposes.
Moreover, some instruments are equipped with a calibrated camera to add RGB color data to the intensity data.
Since a TLS survey, including the corresponding data processing and analysis, can be carried out in relatively short
time, an operational procedure can be planned and executed. The TLS and other remote sensing techniques, like
digital photogrammetry, can be integrated to profit from the strength of each single technique and overcome the
corresponding weakness, leading to a better modeling of the observed system.
We show the results of observations on three Italian volcanoes by using a TLS recently implemented in the moni-
toring system of the INGV. The most complete set has been acquired on Mt. Vesuvius crater in May 2005, October
2006 and June 2009. The whole crater was measured with several overlapped scans and the corresponding digital
surface models were generated and registered into the UTM-WGS84 reference frame. The comparison between
the models leads to an evaluation of the occurred changes. The deformation maps showed a progressive mass loss
due to rock-falls in an area of about 5000 m2 with a corresponding accumulation at the bottom of the crater. The
volume loss which occurred from 2005 to 2009, was computed by subtraction of volumes defined with respect
to reference planes parallel to the caldera walls and was estimated to be 20300 m3. Some results were also in-
terpreted on the basis of micro-seismic and meteorological data in order to plan a monitoring technique where
seismic signals related to rock-fall and/or signals of intense rainfalls are used as alarms for fast TLS surveys able
to characterize the corresponding changes of the caldera walls. The proposed methodology, in particular the simple
but effective approach used in the estimation of volume uncertainties, can be applied to each rock slope instability
phenomenon, regardless to the particular environment.
Two measurements were carried out at Vulcano in April 2009, by surveying the whole “La Fossa” crater and
the “La Forgia” unstable slope, and in April 2010, by re-surveying again the “La Forgia” slope. All measurements
were acquired with several overlapped scans. The comparison between the two measurements at “La Forgia” shows
small change in the morphology that will be further investigated by new measurements; new measures will also be
carried out to image again the “La Fossa” crater.
Measurements at Stromboli were aimed at testing the capability of the technique in very difficult surveying con-
ditions: the 2007 lava fan in the Sciara del Fuoco, an inaccessible and unstable area of the Stromboli volcano. In
such a condition, TLS observes the fan only with high incidence angles and from distances longer than La Fossa
case. In addition, the lava fan consists in black porous lavas, characterized by a bad reflectivity.PublishedVienna, Austria 3–8 April 20111.3. TTC - Sorveglianza geodetica delle aree vulcaniche attiveope
TLS MITM attack on the Ripple XRP Ledger
No full textThe Ripple XRP Ledger network hosts a cryptocurrency called XRP which uses the TLS protocol to send messages between nodes. It is crucial that the network is tested against attacks to ensure its security. The Ripple XRP Ledger could be vulnerable to a Man-in-the-Middle (MITM) attack. This MITM attack is an attack which can intercept and modify data by posing as intended receiver of the message. Potentially, this could have major implications as message content could be intercepted and used maliciously. Therefore this paper aims to answer the question: ``Is it possible to conduct a TLS MITM attack on the XRP ledger to gain access to message content and how does such an attack affect the performance of the system?". The research done in this paper concluded that it is possible to conduct a TLS MITM attack on the XRP Ledger. The impact on performance is a delay in the travel time of a message. However, how big this delay is, is dependent on the network the attack is executed on. In the tested environment it was roughly adding a 69.2\% delay to a message. Future research is necessary to be able to modify the message content and to confirm if the larger the delay added by the MITM, the higher the probability that the MITM is detected.CSE3000 Research ProjectComputer Science and Engineerin
An improved coherent point drift method for tls point cloud registration of complex scenes
No full textProcessing unorganized 3D point clouds is highly desirable, especially for the applications in complex scenes (such as: mountainous or vegetation areas). Registration is the precondition to obtain complete surface information of complex scenes. However, for complex environment, the automatic registration of TLS point clouds is still a challenging problem. In this research, we propose an automatic registration for TLS point clouds of complex scenes based on coherent point drift (CPD) algorithm combined with a robust covariance descriptor. Out method consists of three steps: the construction of the covariance descriptor, uniform sampling of point clouds, and CPD optimization procedures based on Expectation-Maximization (EM algorithm). In the first step, we calculate a feature vector to construct a covariance matrix for each point based on the estimated normal vectors. In the subsequent step, to ensure efficiency, we use uniform sampling to obtain a small point set from the original TLS data. Finally, we form an objective function combining the geometric information described by the proposed descriptor, and optimize the transformation iteratively by maximizing the likelihood function. The experimental results on the TLS datasets of various scenes demonstrate the reliability and efficiency of the proposed method. Especially for complex environments with disordered vegetation or point density variations, this method can be much more efficient than original CPD algorithm.Optical and Laser Remote Sensin
A priori and a posteriori analysis of the hybrid two-level large-eddy simulation method for high Reynolds number complex flows
No full textWe present a priori and a posteriori analysis of the assumptions and predictions of the hybrid two-level large-eddy simulation (TLS-LES) method for high Reynolds number complex flows. The TLS-LES methodology is a multi-scale framework for simulation of turbulent flows in complex configurations at practically relevant Reynolds number. It additively combines the two-level simulation (TLS) model with a conventional large-eddy simulation (LES) approach by employing a static or dynamic blending function. In the present study, first we analyze the model assumptions employed by the TLS model to obtain the small-scale solution necessary for closure of the large-scale equations. Afterward, we analyze the large-scale and small-scale solutions to assess the predictive ability of the multi-scale framework for specific turbulence physics such as role of forward and backscatter of energy and presence of co- and counter-gradient diffusion. To perform these investigations, we consider cases with increasing degree of geometrical complexity, namely, flow in a periodic channel, flow past a bump placed on the lower surface of the channel and flow past a finite-span NACA0015 airfoil
PCNA Ubiquitination Is Important, But Not Essential for Translesion DNA Synthesis in Mammalian Cells
No full textTranslesion DNA synthesis (TLS) is a DNA damage tolerance mechanism in which specialized low-fidelity DNA polymerases bypass replication-blocking lesions, and it is usually associated with mutagenesis. In Saccharomyces cerevisiae a key event in TLS is the monoubiquitination of PCNA, which enables recruitment of the specialized polymerases to the damaged site through their ubiquitin-binding domain. In mammals, however, there is a debate on the requirement for ubiquitinated PCNA (PCNA-Ub) in TLS. We show that UV-induced Rpa foci, indicative of single-stranded DNA (ssDNA) regions caused by UV, accumulate faster and disappear more slowly in Pcna(K164R/K164R) cells, which are resistant to PCNA ubiquitination, compared to Pcna(+/+) cells, consistent with a TLS defect. Direct analysis of TLS in these cells, using gapped plasmids with site-specific lesions, showed that TLS is strongly reduced across UV lesions and the cisplatin-induced intrastrand GG crosslink. A similar effect was obtained in cells lacking Rad18, the E3 ubiquitin ligase which monoubiquitinates PCNA. Consistently, cells lacking Usp1, the enzyme that de-ubiquitinates PCNA exhibited increased TLS across a UV lesion and the cisplatin adduct. In contrast, cells lacking the Rad5-homologs Shprh and Hltf, which polyubiquitinate PCNA, exhibited normal TLS. Knocking down the expression of the TLS genes Rev3L, PolH, or Rev1 in Pcna(K164R/K164R) mouse embryo fibroblasts caused each an increased sensitivity to UV radiation, indicating the existence of TLS pathways that are independent of PCNA-Ub. Taken together these results indicate that PCNA-Ub is required for maximal TLS. However, TLS polymerases can be recruited to damaged DNA also in the absence of PCNA-Ub, and perform TLS, albeit at a significantly lower efficiency and altered mutagenic specificity
SSL and TLS designing and building secure systems
No full text"This book not only describes how SSL/TLS is supposed to behave but also uses the author's free ssldump diagnostic tool to show the protocols in action. The author covers each protocol feature, first explaining how it works and then illustrating it in a life implementation. This presentation bridges the difficult gap between specification and implementation that is a common source of confusion and incompatibility."--BOOK JACKET
AdQSM: A New Method for Estimating Above-Ground Biomass from TLS Point Clouds
No full textForest above-ground biomass (AGB) can be estimated based on light detection and ranging (LiDAR) point clouds. This paper introduces an accurate and detailed quantitative structure model (AdQSM), which can estimate the AGB of large tropical trees. AdQSM is based on the reconstruction of 3D tree models from terrestrial laser scanning (TLS) point clouds. It represents a tree as a set of closed and complete convex polyhedra. We use AdQSM to model 29 trees of various species (total 18 species) scanned by TLS from three study sites (the dense tropical forests of Peru, Indonesia, and Guyana). The destructively sampled tree geometry measurement data is used as reference values to evaluate the accuracy of diameter at breast height (DBH), tree height, tree volume, branch volume, and AGB estimated from AdQSM. After AdQSM reconstructs the structure and volume of each tree, AGB is derived by combining the wood density of the specific tree species from destructive sampling. The AGB estimation from AdQSM and the post-harvest reference measurement data show a satisfying agreement. The coefficient of variation of root mean square error (CV-RMSE) and the concordance correlation coefficient (CCC) are 20.37% and 0.97, respectively. AdQSM provides accurate tree volume estimation, regardless of the characteristics of the tree structure, without major systematic deviations. We compared the accuracy of AdQSM and TreeQSM in modeling the volume of 29 trees. The tree volume from AdQSM is compared with the reference value, and the determination coefficient (R2), relative bias (rBias), and CV-RMSE of tree volume are 0.96, 6.98%, and 22.62%, respectively. The tree volume from TreeQSM is compared with the reference value, and the R2, relative Bias (rBias), and CV-RMSE of tree volume are 0.94, −9.69%, and 23.20%, respectively. The CCCs between the volume estimates based on AdQSM, TreeQSM, and the reference values are 0.97 and 0.96. AdQSM also models the branches in detail. The volume of branches from AdQSM is compared with the destructive measurement reference data. The R2, rBias, and CV-RMSE of the branches volume are 0.97, 12.38%, and 36.86%, respectively. The DBH and height of the harvested trees were used as reference values to test the accuracy of AdQSM’s estimation of DBH and tree height. The R2, rBias, and CV-RMSE of DBH are 0.94, −5.01%, and 9.06%, respectively. The R2, rBias, and CV-RMSE of the tree height were 0.95, 1.88%, and 5.79%, respectively. This paper provides not only a new QSM method for estimating AGB based on TLS point clouds but also the potential for further development and testing of allometric equations.Urban Data Scienc
The Tumor Immune Landscape and Architecture of Tertiary Lymphoid Structures in Urothelial Cancer
No full textCandidate immune biomarkers have been proposed for predicting response to immunotherapy in urothelial cancer (UC). Yet, these biomarkers are imperfect and lack predictive power. A comprehensive overview of the tumor immune contexture, including Tertiary Lymphoid structures (TLS), is needed to better understand the immunotherapy response in UC. We analyzed tumor sections by quantitative multiplex immunofluorescence to characterize immune cell subsets in various tumor compartments in tumors without pretreatment and tumors exposed to preoperative anti-PD1/CTLA-4 checkpoint inhibitors (NABUCCO trial). Pronounced immune cell presence was found in UC invasive margins compared to tumor and stroma regions. CD8+PD1+ T-cells were present in UC, particularly following immunotherapy. The cellular composition of TLS was assessed by multiplex immunofluorescence (CD3, CD8, FoxP3, CD68, CD20, PanCK, DAPI) to explore specific TLS clusters based on varying immune subset densities. Using a k-means clustering algorithm, we found five distinct cellular composition clusters. Tumors unresponsive to anti-PD-1/CTLA-4 immunotherapy showed enrichment of a FoxP3+ T-cell-low TLS cluster after treatment. Additionally, cluster 5 (macrophage low) TLS were significantly higher after pre-operative immunotherapy, compared to untreated tumors. We also compared the immune cell composition and maturation stages between superficial (submucosal) and deeper TLS, revealing that superficial TLS had more pronounced T-helper cells and enrichment of early TLS than TLS located in deeper tissue. Furthermore, superficial TLS displayed a lower fraction of secondary follicle like TLS than deeper TLS. Taken together, our results provide a detailed quantitative overview of the tumor immune landscape in UC, which can provide a basis for further studies.Pattern Recognition and Bioinformatic
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