Optimization-Based Online Initialization and Calibration of Monocular Visual-Inertial Odometry Considering Spatial-Temporal Constraints

The online system state initialization and simultaneous spatial-temporal calibration are critical for monocular Visual-Inertial Odometry (VIO) since these parameters are either not well provided or even unknown. Although impressive performance has been achieved, most of the existing methods are designed for filter-based VIOs. For the optimization-based VIOs, there is not much online spatial-temporal calibration method in the literature. In this paper, we propose an optimization-based online initialization and spatial-temporal calibration method for VIO. The method does not need any prior knowledge about spatial and temporal configurations. It estimates the initial states of metric-scale, velocity, gravity, Inertial Measurement Unit (IMU) biases, and calibrates the coordinate transformation and time offsets between the camera and IMU sensors. The work routine of the method is as follows. First, it uses a time offset model and two short-term motion interpolation algorithms to align and interpolate the camera and IMU measurement data. Then, the aligned and interpolated results are sent to an incremental estimator to estimate the initial states and the spatial–temporal parameters. After that, a bundle adjustment is additionally included to improve the accuracy of the estimated results. Experiments using both synthetic and public datasets are performed to examine the performance of the proposed method. The results show that both the initial states and the spatial-temporal parameters can be well estimated. The method outperforms other contemporary methods used for comparison.

System-based definition and measurement of the professional position of the individual cadet of a departmental university

The article is devoted to the system-based analysis of the definition and measurement of the professional position of the individual cadet of a departmental university. A basis is a set of elements that is characterized by completeness, orderliness, and measurability. The «set of elements» has the following «substrate characteristics» such as «relation», «mapping» and «transformation», which define the first level of «immersion» in the concept of «basis». In turn, at thesecond level of «immersion» in the concept of «basis», corresponding to three factors («completeness», «orderliness», «measurability»), there are corresponding triple characteristics that determine the third level of «immersion»: 1) «full» is «factorness», «multiply connected» and «integrity»; 2) «the order» is «symmetry», «dichotomy» and «adenomasness»; 3) «measurable» is a «measure», «projection» and «rating». At all three levels of «integration» into the concept of «basis» there is a single generalized dichotomy «external – internal», which in our article is projected on a separate personal dichotomy «social-individual». «Multi-connectivity» means the existence of many dichotomous factors for which there is no single dichotomy, i.e. there is no «node» with a single factor dichotomy (reminiscent of Kettell's factor strategy, consisting of 16 different factor dichotomies in his typology of personality qualities, where there is no single dichotomy). «Unconnectedness» means the existence of a set of factors for which there is a single dichotomy, i.e. there is a «node» with a single factor dichotomy. In the «dimension», the following triples are obtained: 1) measure the representation (image, word, number), 2) projection of data conversion (image to word, image number words number). The last conversion (words to numbers) will be used in this article, and it is, by the way, more common in measurement diagnostic practice. 3) the assessment of the level of measurement of information (low, medium, high) will be used in this article and, by the way, it is also more common in measuring diagnostic practice. In our article, «completeness» is defined by a factorial multi-connected integral set of types. «Orderliness» is defined by a symmetric-dichotomous unconnected factorial verbal structure of a set of types (a single dichotomous multi-factorial verbal structure of types or «verbal basis»). The «measurability»of types is associated with a single dichotomous verbal-numerical evaluation metric scale or with a «numerical basis». «Measurability» makes it possible to create dichotomous basic multifactorial methods based on a dichotomous symmetric verbal-numerical scale evaluation of types.

Grip Strength-Endurance in Ambitious and Recreational Climbers: Does the Strength Decrement Index Serve as a Feasible Measure?

The present study investigated the time course of repetitive maximal isometric grip strength, depending on the arm position, laterality (dominant vs. non-dominant side), and climbing level. The intervention aimed to provide a feasible indicator of maximal strength-endurance in climbing. Seventeen recreational (climbing level (CL): 6.8 (SD 0.5) on the Union Internationale des Associations d’Alpinisme (UIAA) metric scale) and eleven ambitious (CL: 8.7 (SD 0.6) UIAA metric scale) climbers (age: 27 (8) years; BMI: 21.6 (1.9) kg/m2; ape index (arm span divided by body height): 1.05 (0.18); training volume: 2.2 (1.0) h/week). Participants completed maximal isometric handgrip strength (Fmax) tests in four positions (left and right hand beside the trunk as well as left and right hand above the shoulder) plus twelve repetitive work-relief cycles, lasting 4 and 1 s where isometric strength, heart rate, and perceived exertion were recorded. Fmax differed between groups in nearly all positions. A large side × position × time × group interaction was observed for repetitive isometric grip strength (p = 0.009, ηp2 = 0.71). However, subsequent post-hoc tests did not reveal a significant difference between groups during each testing position. Additional correlation analysis between asymmetry and CL showed an inverse relationship for ambitious climbers (r = −0.71). In conclusion, the degree of grip strength decline did not relevantly differentiate between ambitious and recreational climbers. Thus, the time course of handgrip strength seems to mainly rely on maximal grip strength during the first contraction.

Detection and Delineation of Sorted Stone Circles in Antarctica

Sorted stone circles are natural surface patterns formed in periglacial environments. Their relation to permafrost conditions make them very helpful for better understanding the past climates where they were formed and have evolved and also for monitoring current underlying processes in case circles are active. These metric scale patterns that occur in clusters of tens to thousands of circular elements, can be more comprehensively characterized if automated methods are used. This paper addresses their identification and delineation through the development and testing of a set of automated approaches, namely, template matching, sliding band filter, and dynamic programming. All of these methods take advantage of the 3D shape of the structures conveyed by digital elevation models (DEM), built from ultra-high resolution imagery captured by unmanned aerial vehicles (UAV) surveys developed in Barton Peninsula, King George Island, Antarctica (62°S). The best detection results achieve scores above 85%, while the delineations are performed with errors as low as 7%.