Dynamic Point Cloud Compression Based on Projections, Surface Reconstruction and Video Compression

In this paper we will present a new dynamic point cloud compression based on different projection types and bit depth, combined with the surface reconstruction algorithm and video compression for obtained geometry and texture maps. Texture maps have been compressed after creating Voronoi diagrams. Used video compression is specific for geometry (FFV1) and texture (H.265/HEVC). Decompressed point clouds are reconstructed using a Poisson surface reconstruction algorithm. Comparison with the original point clouds was performed using point-to-point and point-to-plane measures. Comprehensive experiments show better performance for some projection maps: cylindrical, Miller and Mercator projections.

Super Edge 4-Points Congruent Sets-Based Point Cloud Global Registration

With the acceleration in three-dimensional (3D) high-frame-rate sensing technologies, dense point clouds collected from multiple standpoints pose a great challenge for the accuracy and efficiency of registration. The combination of coarse registration and fine registration has been extensively promoted. Unlike the requirement of small movements between scan pairs in fine registration, coarse registration can match scans with arbitrary initial poses. The state-of-the-art coarse methods, Super 4-Points Congruent Sets algorithm based on the 4-Points Congruent Sets, improves the speed of registration to a linear order via smart indexing. However, the lack of reduction in the scale of original point clouds limits the application. Besides, the coplanarity of registration bases prevents further reduction of search space. This paper proposes a novel registration method called the Super Edge 4-Points Congruent Sets to address the above problems. The proposed algorithm follows a three-step procedure, including boundary segmentation, overlapping regions extraction, and bases selection. Firstly, an improved method based on vector angle is used to segment the original point clouds aiming to thin out the scale of the initial point clouds. Furthermore, overlapping regions extraction is executed to find out the overlapping regions on the contour. Finally, the proposed method selects registration bases conforming to the distance constraints from the candidate set without consideration about coplanarity. Experiments on various datasets with different characteristics have demonstrated that the average time complexity of the proposed algorithm is improved by 89.76%, and the accuracy is improved by 5 mm on average than the Super 4-Points Congruent Sets algorithm. More encouragingly, the experimental results show that the proposed algorithm can be applied to various restrictive cases, such as few overlapping regions and massive noise. Therefore, the algorithm proposed in this paper is a faster and more robust method than Super 4-Points Congruent Sets under the guarantee of the promised quality.

Study of the Effect of Exploiting 3D Semantic Segmentation in LiDAR Odometry

This paper presents a study of how the performance of LiDAR odometry is affected by the preprocessing of the point cloud through the use of 3D semantic segmentation. The study analyzed the estimated trajectories when the semantic information is exploited to filter the original raw data. Different filtering configurations were tested: raw (original point cloud), dynamic (dynamic obstacles are removed from the point cloud), dynamic vehicles (vehicles are removed), far (distant points are removed), ground (the points belonging to the ground are removed) and structure (only structures and objects are kept in the point cloud). The experiments were performed using the KITTI and SemanticKITTI datasets, which feature different scenarios that allowed identifying the implications and relevance of each element of the environment in LiDAR odometry algorithms. The conclusions obtained from this work are of special relevance for improving the efficiency of LiDAR odometry algorithms in all kinds of scenarios.

To the question of S.S. Zimnitsky on the origin of the giant T wave after ventricular extrasystole on an electrocardiogram

The study of life, medical and scientific activities of the outstanding domestic scientist S.S. Zimnitsky always causes and will cause great interest. The versatility of his talent as a scientist continues to amaze. Many of the issues that remain relevant today raised by S.S. Zimnitsky, not fully resolved in the XXI century. There were no answers to the well-known question asked by the seriously ill S.S. Zimnitsky to another prominent Russian scientist, the beacon of Russian physiological science A.F. Samoilov. This question concerned the origin of the giant positive T wave in the first QRS complex after the ventricular extrasystole on the electrocardiogram. The question remained unanswered. We believe that this was because by the end of the 20s of the XX century (S.S. Zimnitsky died in 1927), the delicate mechanisms of repolarization processes were not able to understand, in both healthy and diseased myocardium. The article sets forth our original point of view on the genesis of such a T wave in S.S. Zimnitsky. We believe that a scientific discussion on this issue is quite possible. There is no doubt that both life and scientific activities of S.S. Zimnitsky has always attracted and will attract the attention of both medical historians and practical doctors, scientists and inquisitive students.

How Is the Confidentiality of Crime Locations Affected by Parameters in Kernel Density Estimation?

Kernel density estimation (KDE) is widely adopted to show the overall crime distribution and at the same time obscure exact crime locations due to the confidentiality of crime data in many countries. However, the confidential level of crime locational information in the KDE map has not been systematically investigated. This study aims to examine whether a kernel density map could be reverse-transformed to its original map with discrete crime locations. Using the Epanecknikov kernel function, a default setting in ArcGIS for density mapping, the transformation from a density map to a point map was conducted with various combinations of parameters to examine its impact on the deconvolution process (density to point location). Results indicate that if the bandwidth parameter (search radius) in the original convolution process (point to density) was known, the original point map could be fully recovered by a deconvolution process. Conversely, when the parameter was unknown, the deconvolution process would be unable to restore the original point map. Experiments on four different point maps—a random point distribution, a simulated monocentric point distribution, a simulated polycentric point distribution, and a real crime location map—show consistent results. Therefore, it can be concluded that the point location of crime events cannot be restored from crime density maps as long as parameters such as the search radius parameter in the density mapping process remain confidential.

Nietzsches affirmative Genealogien

This paper argues that besides the critical and historically informed genealogies of his later work, Nietzsche also sketched out genealogies that are not historically situated and that display an under-appreciated affirmative aspect. The paper begins by looking at two early examples of such genealogies where datable historical origins are clearly not at issue, which raises the question of what kind of origins Nietzsche is seeking. It is argued that these genealogies inquire into practical origins – into the original point of certain conceptual practices given certain needs – and that this reflects Nietzsche’s instrumentalist approach to concepts. It is then argued that this focus lends the genealogies an affirmative dimension, because they present their object as naturalistically intelligible and practically indispensable. Finally, it is shown how the nature and limits of this affirmative dimension can be tentatively sharpened by connecting it to Nietzsche’s later notion of an economic justification of morality.

Optimal Collision-Free Grip Planning for Biped Climbing Robots in Complex Truss Environment

Biped climbing robots (BiCRs) can overcome obstacles and perform transition easily thanks to their superior flexibility. However, to move in a complex truss environment, grips from the original point to the destination, as a sequence of anchor points along the route, are indispensable. In this paper, a grip planning method is presented for BiCRs generating optimal collision-free grip sequences, as a continuation of our previous work on global path planning. A mathematic model is firstly built up for computing the operational regions for negotiating obstacle members. Then a grip optimization model is proposed to determine the grips within each operational region for transition or for obstacle negotiation. This model ensures the total number of required climbing steps is minimized and the transition grips are with good manipulability. Lastly, the entire grip sequence satisfying the robot kinematic constraint is generated by a gait interpreter. Simulations are conducted with our self-developed biped climbing robot (Climbot), to verify the effectiveness and efficiency of the proposed methodology.

Understanding the concept of Marma and their clinical applicaion in Shalya Tantra w.s.r. to Vital points

Marma therapy is the original point system of healing in the body. “Marma” come from the sanskrit “Mru” and which means “To kill” the 107 Marma points are categorised in terms of their effect on the vitality of the body. Marma is one of the unique and important topics discussed in Ayurveda. It plays an important role in surgery. Hence it is rightly called as Shalya Vishayardha. Marma plays a significant clinical role and may be correlated to the Acupressure/Acupuncture. Marma are the critical points of body associated with different organs and nerves. Ayurveda describe use of Marma therapy for various diseases and identification of Marma points which is to be cured, since injury to these Marma points may causes serious harmful effect. Different types of muscles, veins, bones, ligaments and joints meets with each other at the Marma point thus these points acts as a physiological junction. Discussion of Marma points is found in most of the great texts of Ayurveda but the most famous text to explore the subject is the Sushruta Samhita. Vaidya Sushruta described ‘the locations of the Marma points, as well as how they influence Prana. He stated that it is important for the surgeon to have knowledge of these points for the purpose of avoiding them, so as to cut into them could result in a catastrophic outcome. This article summarizes various perspectives of Marma and their clinical importance as per Ayurveda.

James and Pragmatism: The Road Not Taken

William James envisaged pragmatism as a reform of philosophy. Like his fellow pragmatist John Dewey, he held that the history of philosophy often shows how questions, once relevant and exciting, inspire a sequence of derivative and ever-narrower inquiries, in which the original point becomes lost. To read James’s pragmatism in this way distinguishes it from the reforming efforts of the logical positivists, whose concerns with “cognitive significance” and “meaningful language” neither he nor Dewey shared. Viewed in this light, James’s version of Charles Sanders Peirce’s pragmatic maxim, his theory of truth, and his interest in reconciling the claims of science and religion take on new significance. His discussions point toward a road less traveled, one that twentieth-century Anglophone philosophy did not take.

Marching Forward, Marching in Circles: A History of Problems and Dilemmas in Teacher Preparation

This essay tracks the history of teacher preparation, from its origins in the early republic to the present. In so doing, it tells two stories. The first is a story about problems—a linear story in which problems are discovered, potential solutions are generated, and positive results are achieved. It moves from the past to the future and from the old to the new. The other story is about dilemmas. And because dilemmas cannot be solved, the passage of time leads back to the original point of departure. Solutions are tried and discarded, but as the past is forgotten, they eventually are embraced again. In telling these two stories, the essay proceeds chronologically, highlighting improvements in teacher preparation practice over time. That relatively linear chronology, however, is organized into four periods, which reveal not a march of progress, but an unmindful return to the once-maligned practices of the past.