Height Of Object Research Articles

Geospatial modeling, analysis and mapping for aerodrome land development

The article discusses aerodrome geospatial modeling methods and geoinformation analysis for determining land use zones and obstacle restriction areas. Tall trees, buildings and structures, exceeding special limitation surfaces in the aerodrome flight areas, are obstacles that are dangerous. Using spatial modelling, which determines maximal permissible heights, it is proposed to predict the heights of natural and artificial vertical objects in order to analyse and plan land use capabilities. As a basis for spatial modeling, it is proposed to use stereoscopic models with a resolution of 0.3m, built on aircraft-based scanner images. Using the methods of geoinformation analysis, it is suggested to make horizontal zoning of aerodrome areas according to the most important air navigation safety and ecological indicators (power lines, roads, permitted classes of construction objects location). The study presents the research results of the proposed methodology for the Republic of Belarus aerodrome.

Design of low-cost and simple reconstruction method for Three Dimensional Electrical Impedance Tomography (3D-EIT) Imaging

Electrical impedance tomography is a non-invasive imaging modality that uses the electrical conductivity distribution to reconstruct images based on potential measurements from the object's surface. The proposed study was to design and fabricate a low-cost and simple reconstruction method for 3D electrical impedance tomography imaging. In this study, we have been successfully developed 3 Dimensional Electrical Impedance Tomography (3D-EIT) system using 16 copper electrodes (Cu) to detect and reconstruct the presence of objects in the Phantom. 3D-EIT was developed using Phantom as a test object with PVC pipe material, with an inner diameter of 7.2 cm and a height of 5.4 cm. Electrodes were arranged in two rings, with each ring having eight electrodes arranged in a planar line. Furthermore, the Gauss-Newton algorithm and Laplace prior regularization were used to image reconstruction of objects inside the Phantom using voltage measurement produced from sequential pairs of neighboring electrodes. The voltage is obtained from the injection of a constant current of 1 mA at 20 kHz into the system's electrode pairs. The objects used in this research are PVC pipe, solid aluminum, PVC pipes filled with wax glue, and copper trusses. The results obtained show that the reconstruction results can provide information about the position, the electrical properties, and the shape of real objects. Finally, the system can detect the location, height, and electrical properties of objects for all variations of angle and height variations.

The Influence of Perch Height Selection on Vocalization of Pied Triller, Lalage nigra (Aves: Campephagidae) in Suburban Landscapes, Sarawak

Understanding how birds utilised songs and calls to communicate among conspecifics is crucial for their survival, yet it remains an understudied area in bird ecology. We studied the influence of perch height selection on the vocalisation of Pied Triller, a common garden bird, in two suburban landscapes namely Pustaka Negeri Sarawak Recreational Park, Kuching and Universiti Malaysia Sarawak campus, Kota Samarahan from October 2018 to February 2019. Using a Marantz recorder connected to a parabolic reflector, we recorded calls and songs during morning (0630-1030 hr) and late afternoon (1600-1830 hr). Perch object, tree species, roost substrate and perch height from the ground were identified and measured. Clear and good quality spectrograms were used directly to describe song and call types. Photos and video recordings were analysed to describe perch behaviour. The vocal output representatives were then matched to the corresponding behaviour displayed. Our results revealed that Pied Trillers emit four different vocal outputs namely (i) song type, (ii) call type A, (iii) call type B and (iv) call type C. A total of nine behaviours were observed, of which the perch-hop behaviour was observed the most from both male and female Pied Trillers (33.71%), followed by perching (29.21%), foraging (20.22%), preening (7.78%), defecating (2.25%), eating (2.25%), roosting (2.25%), bill wipe (1.12%) and flight (1.12%). They prefer to roost on high perch to emit calls compared to songs. This probably suggest that Pied Triller prioritised vocal transmission and signalling to avoid being masked by surrounding anthropogenic noises and to avoid being conspicuous to potential predators. The most frequently visited perch object was the Weeping fig tree, Ficus benjamina.
 
 Keywords: Call, perch height, Pied Triller, song, suburban landscapes

Constructing 3D Models of Rigid Objects from Satellite Images with High Spatial Resolution Using Convolutional Neural Networks

A way of constructing 3D models of rigid objects from one satellite image is described. It is based on the use of two convolution neural networks which sequentially process high-resolution satellite images. The first neural network performs integral image analysis for segmentation and identification of objects of specified physical classes. The second neural network performs local image analysis and works with images segmented by the first neural network in areas of the image that presumably contain objects of specified classes. An algorithm for reconstructing a 3D model of an object from raster domains of a segmented image obtained from local analysis is described. It is based on regression analysis, the assessing of equivalent figures, and the linearization and polarization of contours. Results from the algorithm’s operation are given using the example of railway infrastructure facilities. The results from constructing 3D models of three objects of the railway infrastructure, identified via the operation of neural networks for four informative classes of areas are presented, e.g. roofs, walls, railroad tracks, contanc lines (poles). Standard dimensions (e.g., the railway gauge (1.52 m) and the height of railway support poles (11.35 m)) are used to estimate scaling coefficients that allow determination of base dimensions and object heights. The possibility of constructing 3D models of objects of areas from 210 to 4200 m2 is shown.

Strategy for Application of Support Object for Fall Prevention in the Elderly Based on Balance Recovery Characteristics

This research proposes a strategy for applying support objects—equipment, tools, and even furniture/environment from which humans can receive reaction force through their hands—for fall prevention in the elderly. This paper presents an assessment example of support objects based on balance recovery characteristics and a discussion regarding their application according to the assessment results. The balance recovery characteristics depend on the direction in which reaction force can be obtained based on the shape of the support object and direction in which the force is easily exerted on the hand. Evaluation indices for assessing the height and shape of nonportable support objects and determining a position of the tip on the ground of a cane, a typical portable support object, in the anterior direction are briefly introduced based on the authors’ previous works. The strategy for the application of support objects utilizing the evaluation indices is proposed; better use of support objects, their locations, new-shaped ones, and support devices with a new design concept are discussed and introduced based on the values of the calculated indices according to the type/usage of the support objects.

Determining the Accuracy of Measuring the Heights of Objects in the Automatic Processing of Stereo Images

Introduction. Currently, information on the spatial description of objects is used in many areas of human activity. One of these types of information are the coordinates of the objects. These data are used in cartography, the construction of digital maps and 3D models, for the operation of the navigation means, etc. There are many software for design and analysis of digital elevation models. These are modules and packages like Spatial Analyst, 3D Analyst, ArcGIS packages, program MapInfo (MapInfo Corp.), Autodesk Map 3D of AutoCAD (Autodesk Inc.) and others. Common to them is build automation of soprovich terrain models, including the combination of the images of the stereopair, what is necessary to measure heights of objects for automated creation of digital elevation models of the earth's surface one of the key quality indicators is the accuracy of determining the heights of objects. The main influence on this indicator provides measurement error of parallax when processing stereosystem. Obtaining analytical expressions for the accuracy of the determination of the height of the object. To obtain the formula of calculating accuracy of measuring the height of objects used decomposition of the function into a Taylor series. Currently, the standard deviation of measurement errors of height of flight of the aircraft, the basis of stereozone and focal length, usually known with enough high accuracy. The main influence on the accuracy of determining the heights of objects during automatic processing of images is the accuracy of parallax. When measuring parallax, the problem is reduced to the search and discovery of images of the object in the second picture on the image of the object on the first image and measuring its position over images of other objects and noise. Using the formula of Kramer-Rao for the potential measurement accuracy of the image coordinates of the object in the picture, the Fourier transform and the parseval equality proof the identity, the formula obtained accuracy potential of combining stereochemical (measurement of parallax). We used the extreme-correlation combination method, as it can be applied for virtually any signals and systems of measurement. Analysis of the obtained results. The analysis of the obtained formulas shows that the overlay accuracy of the images deteriorates with the increase of the power spectral density of the noise on the first and second images and reducing the similarity of one image with another and also with the decrease in the effective width of a mutual spectrum spatial stereo. Increasing the value of the basis stereozone error of measurement of heights of objects first improves and then deteriorates. This deterioration is caused by the fact that the images of a stereo pair are obtained from different spatial points and images arise of perspective distortion and the distortion due to relief. Accordingly, as the base of removal increases, these distortions will increase. Conclusions. The advantage of this approach is the use of finite analytical expression. It provides the ability to calculate the potential accuracy of defining object heights when building a DMR with modern applications. The disadvantages include the complexity of calculating the moments of mutual spatial spectrum of stereo images. This approach can be applied when planning the shooting mode and the Earth surface imaging equipment for mapping, 3D models, etc.

Optimizing the Achievable Information Content Extraction from WorldView-4 Stereo Imagery

In 2016, DigitalGlobe’s third-generation commercial Earth observation satellite WorldView-4 (WV-4), which offered 31 cm spatial resolution for panchromatic imagery, was launched and was active up to January 2019. Together with WorldView-3, this is the highest ground resolution of civilian optical space-borne missions. In this study, the information content of WV-4′s pan-sharpened stereo imagery is comprehensively investigated by manual and automatic object extraction approaches in a study area with rolling urban topography. The potential of automatic extraction was maximised by a group of refinement methods supported by the normalised digital surface model (NDSM) generated from WV-4 stereo pair. The NDSM was used as an additional band in the segmentation for revealing the object height heterogeneity. The results demonstrated that our method increased the precision, completeness and overall quality of WV-4 automatic extraction up to 8.4% for the number of buildings and up to 3.4% for the road length.

An imaging performance analysis method correlated with geometrical deviation for the injection molded high-precision aspheric negative plastic lens

High-precision aspheric negative plastic lenses are widely used in optical systems owing to their excellent performance and ease of high-efficiency manufacturing. The imaging performance of the lens is difficult to control, because it is unable to perform optical measurements directly and is sensitive to manufacturing processing meanwhile. Generally, the imaging performance is guaranteed by a strict control of geometrical deviation, such as Peak-to-Valley (PV) and Root-Mean-Square (RMS). In this study, an optical ray-tracing algorithm with the measured geometrical deviation data is proposed to perform an imaging performance analysis correlated with geometrical deviation for the injection molded high-precision aspheric negative plastic lens. Taguchi experiments are applied to investigating the effect of processing parameters. The geometrical deviation of the convex surface is found to be an order of magnitude greater than that of the concave surface. The geometrical dimension of the concave surface is mainly determined by the machining precision of the mold cavity surface, whereas the convex surface dimension is mainly affected by the lens shrinkage. However, the imaging performance has a nonlinear correlation with the geometrical deviation. Modulation Transfer Function (MTF) and Spot Diagram are equivalently affected by the concave and convex geometrical deviations, and depend on the object field height. The effect of processing parameters on geometrical deviation and imaging performance is uncorrelated. Thus, the imaging performance should be simultaneously considered as a criterion as well as the geometrical deviation in the optimization of aspheric negative lens injection molding processing. The imaging performance prediction using an optical ray-tracing algorithm with the measured geometrical deviation data is instrumental to optimize the manufacturing processing.

Movement behaviours and physical, cognitive, and social-emotional development in preschool-aged children: Cross-sectional associations using compositional analyses.

Movement behaviours (e.g., sleep, sedentary behaviour, and physical activity) in isolation have demonstrated benefits to preschool-aged children's development. However, little is known on the integrated nature of movement behaviours and their relationship to healthy development in this age range. Thus, the objective of this study was to examine the relationships between accelerometer-derived movement behaviours and indicators of physical, cognitive, and social-emotional development using compositional analyses in a sample of preschool-aged children. Children (n = 95) were recruited in Edmonton, Canada. Movement behaviours were measured with ActiGraph wGT3X-BT accelerometers worn 24 hours/day. Physical (i.e., body mass index [BMI] z-scores, percent of adult height, and motor skills), cognitive (i.e., working memory, response inhibition, and vocabulary), and social-emotional (i.e., sociability, externalizing, internalizing, prosocial behaviour, and cognitive, emotional, and behavioural self-regulation) development were assessed. Objective height and weight were measured for BMI z-scores and percent of adult height, while the Test of Gross Motor Development-2 was used to assess motor skills. The Early Years Toolbox was used to assess all cognitive and social-emotional development indicators. Compositional linear regression models and compositional substitution models were conducted in R. Children accumulated 11.1 hours of sleep, 6.1 hours of stationary time, 5.1 hours of light-intensity physical activity (LPA), and 1.8 hours of moderate- to vigorous-intensity physical activity (MVPA) per day. Movement behaviour compositions were significantly associated with physical (i.e., locomotor skills, object motor skills, and total motor skills) and cognitive (i.e., working memory and vocabulary) development (R2 range: 0.11-0.18). In relation to other movement behaviours in the composition, MVPA was positively associated with most physical development outcomes; while stationary time had mixed findings for cognitive development outcomes (i.e., mainly positive associations in linear regressions but non-significant in substitution models). Most associations for LPA and sleep were non-significant. The overall composition of movement behaviors appeared important for development. Findings confirmed the importance of MVPA for physical development. Mixed findings between stationary time and cognitive development could indicate this sample engaged in both beneficial (e.g., reading) and detrimental (e.g., screen time) stationary time. However, further research is needed to determine the mechanisms for these relationships.

Characterization of particle emission from thermoplastic additive manufacturing

Abstract Particle emission from fused-deposition modelling (FDM) desktop 3D printer has raised concerns regarding indoor personal health due to the increased accessibility of printers. This study characterises the size, number and morphology of the emitted particles to understand particle formation processes and propose guidelines for their abatement. The effects of extruder temperature, layer height, filament colour and shape of printing object on particle characteristics emitted from a desktop 3D printer have been investigated. For first time, a novel thermogravimetric analysis (TGA) method is developed to emulate printing process, which offers an insight into particle formation during extruder heating, standing-by and during the printing process. Printing temperature and printing layer height demonstrate a major effect on the ultra-fine particles (UFP) emitted, while ABS filament colour shows a minor effect on the nanoparticle emissions. Local temperature and concentration of volatile organic material emitted from the filament play an important role on the number of particles formed, while printing duration and air change rate (ACH) affect particle size, morphology and emission rate. The results provide guidelines to develop printing settings that will lead to lower UFP emissions for improved indoor air quality. The developed TGA method demonstrates the qualitative behaviour of particle emissions from a material under heating, which is approximately proportional to an FDM printers’ particle emissions; facilitating increased repeatability, time and cost efficiency for printing material assessment.

ANALISIS POTENSI TENAGA SURYA PADA PERMODELAN BANGUNAN TIGA DIMENSI BERDASARKAN DATA OPEN STREET MAP (STUDI KASUS: UNIVERSITAS GADJAH MADA YOGYAKARTA)

Energy crisis that occurred in the world after being exploited on a large scale against fossil energy caused people has to think again about renewable energy. In Indonesia, the electricity consumption always increases every year with fossil energy dominating energy sources. Based on the Government Regulation number 79 of 2014, concerning the National Energy Policy, the Government of Indonesia has a national target in the implementation of renewable energy of 23% in 2025 and 31% in 2050. Information disclosure and development of geospatial technology is shown through the availability of information on the dimensions, location, and the height of objects on the surface of the earth through the open street map (OSM) website, one of which is the building. Digital Elevation Model (DEM/DEMNAS) data can be accessed through the Geospatial Information Agency (BIG) website. Utilization of this information can be done by utilizing QGIS and ArcGIS Pro software. The existence of an energy crisis and technological developments led to calculate Solar Radiation (contained in ArcGIS Pro) which can calculate the solar potential at a location based on three-dimensional building data, DEM, and solar intensity. Universitas Gadjah Mada (UGM) has announced their commitment in realizing new and renewable energy in Indonesia. Therefore, researchers intend to find out the solar potential in the UGM region in order to realize government programs in the application of new renewable energy. Based on the analysis done in this research, we get the amount of solar energy potential of 369.543 kWh/ m2/ day. Through this research we hope that UGM can become a pilot campus in the application of renewable energy, solar energy and can reduce the use of conventional electricity using fossil energy.Keywords: Solar Energy Potential, Three Dimensional Building, Open Street Map, UGM.

Discrepancy between subjective and objective measures of obesity amongst the undergraduate medical and dental students: an institution-based cross-sectional study

Background: Obesity has been reported to be assessed both subjectively and objectively, with varying degrees of agreement. This study was conducted to assess the discrepancy between the subjective and objective measures of obesity amongst undergraduate medical and dental students.
 Methods: A cross-sectional study was designed and conducted at College of Medical Sciences and Teaching Hospital, Nepal, from December 2019 to January 2020. First and second year under­graduate medical and dental students were first asked to report their height and weight, which were subsequently measured using standard stadiometer and weighing balance. Body mass index (BMI) was calculated from both subjective and objective height and weight, and was graded into different categories as underweight, normal, overweight and obese.
 Results: Of the 181 participants, 51.4% were males. The prevalences of subjective and objective overweight/obesity were 24.8% and 25.4%, respectively, with the difference being –0.6% (95% CI: –9.5% to 8.4%; p>0.05). Likewise, the differences in prevalence rates were +4.3% (95% CI: –8.6% to 17.2%; p>0.05) in males and –5.7% (95% CI: –17.9% to 6.6%; p>0.05) in females. Further, the differences between the mean values of subjective and objective BMI were +0.4kg/m2 (p=0.086, overall); +0.9kg/m2 (p=0.002, males) and –0.3kg/m2 (p=0.122, females).
 Conclusions: In the face of varying degrees of discrepancy between subjective and objective mea­sures of obesity in overall participants as well as in both gender groups, the findings suggest a reasonable degree of acceptability of the subjective assessment.

DISCREPANCY BETWEEN SUBJECTIVE AND OBJECTIVE MEASURES OF OBESITY AMONGST THE UNDERGRADUATE MEDICAL AND DENTAL STUDENTS: AN INSTITUTION-BASED CROSS-SECTIONAL STUDY

Background: Obesity has been reported to be assessed both subjectively and objectively, with varying degrees of agreement. This study was conducted to assess the discrepancy between the subjective and objective measures of obesity amongst undergraduate medical and dental students.
 Methods: A cross-sectional study was designed and conducted at College of Medical Sciences and Teaching Hospital, Nepal, from December 2019 to January 2020. First and second year under­graduate medical and dental students were first asked to report their height and weight, which were subsequently measured using standard stadiometer and weighing balance. Body mass index (BMI) was calculated from both subjective and objective height and weight, and was graded into different categories as underweight, normal, overweight and obese.
 Results: Of the 181 participants, 51.4% were males. The prevalences of subjective and objective overweight/obesity were 24.8% and 25.4%, respectively, with the difference being –0.6% (95% CI: –9.5% to 8.4%; p>0.05). Likewise, the differences in prevalence rates were +4.3% (95% CI: –8.6% to 17.2%; p>0.05) in males and –5.7% (95% CI: –17.9% to 6.6%; p>0.05) in females. Further, the differences between the mean values of subjective and objective BMI were +0.4kg/m2 (p=0.086, overall); +0.9kg/m2 (p=0.002, males) and –0.3kg/m2 (p=0.122, females).
 Conclusions: In the face of varying degrees of discrepancy between subjective and objective mea­sures of obesity in overall participants as well as in both gender groups, the findings suggest a reasonable degree of acceptability of the subjective assessment.

The use of internet sources for nutritional information is linked to weight perception and disordered eating in young adolescents

The internet serves as an accessible and confidential resource for young adolescents seeking nutritional information. However, the quality of information retrieved online is mixed and could have serious implications for users. Young adolescents who perceive themselves as overweight may be disproportionately affected as they are at greater risk for disordered eating. The current study aimed to (1) assess whether the frequency of use of different internet sources to obtain nutritional information differs between healthy weight young adolescents and those with overweight/obesity based on both objective and perceived weight status and (2) evaluate the relationships between different internet sources utilized for nutritional information and disordered eating. Young adolescents (n = 167; 10–15 years) completed the Children's Eating Attitudes Test (ChEAT; total disordered eating), indicated their perceived weight status, and reported how often they obtained nutritional information from the following internet sources: professional websites, personal websites, social media, commercial weight loss websites, and forums. Objective height and weight measurements were obtained. Young adolescents that perceived themselves to be a little overweight or overweight reported greater use of personal websites (p = .012), commercial weight loss websites (p = .011), and social media (p = .019) for nutritional information than those that did not perceive themselves to be a little overweight or overweight. The frequency of use of internet sources for nutritional information did not differ based on objective weight status. Greater use of each of the internet sources for nutritional information was related to greater disordered eating (p's < 0.05). While longitudinal research is needed to further examine these relationships, healthcare providers and teachers should provide young adolescents with guidance for interpreting and using online nutritional information to encourage valid and reliable health recommendations.

Geometric Recognition of Moving Objects in Monocular Rotating Imagery Using Faster R-CNN

Moving object detection and tracking from image sequences has been extensively studied in a variety of fields. Nevertheless, observing geometric attributes and identifying the detected objects for further investigation of moving behavior has drawn less attention. The focus of this study is to determine moving trajectories, object heights, and object recognition using a monocular camera configuration. This paper presents a scheme to conduct moving object recognition with three-dimensional (3D) observation using faster region-based convolutional neural network (Faster R-CNN) with a stationary and rotating Pan Tilt Zoom (PTZ) camera and close-range photogrammetry. The camera motion effects are first eliminated to detect objects that contain actual movement, and a moving object recognition process is employed to recognize the object classes and to facilitate the estimation of their geometric attributes. Thus, this information can further contribute to the investigation of object moving behavior. To evaluate the effectiveness of the proposed scheme quantitatively, first, an experiment with indoor synthetic configuration is conducted, then, outdoor real-life data are used to verify the feasibility based on recall, precision, and F1 index. The experiments have shown promising results and have verified the effectiveness of the proposed method in both laboratory and real environments. The proposed approach calculates the height and speed estimates of the recognized moving objects, including pedestrians and vehicles, and shows promising results with acceptable errors and application potential through existing PTZ camera images at a very low cost.

Relative Mechanical Load on Shoulder and Elbow Muscles in Standing Position When Handling Materials Manually. A Study of Packing Work

When a patient with a musculoskeletal disorder returns to work after rehabilitation, the work-station should be designed so that the impaired muscle groups are less exposed to load. The work posture desirable for a particular muscle group might impose higher load on another muscle group. Since the shoulder muscles usually are stronger than the elbow muscles, a direct comparison of the loads is difficult. To make comparisons possible, the load moment about the investigated joints were divided by the counteracting maximum muscular moments, and a Muscular strength Utilization Ratio (MUR) was obtained. Using this principle, the muscular load on the shoulder and elbow was investigated in 72 different packing work postures. Different combinations of box size, box angle, edge height and weight of object handled were studied. There was a higher relative load on the shoulder than on the elbow. The concept of relating joint load to strength may serve as a guideline for how high a patient's strength should be before returning to work to avoid further injuries.

Habitat openness and edge avoidance predict Saltmarsh Sparrow abundance better than habitat area

Abstract The Saltmarsh Sparrow (Ammospiza caudacuta) is a tidal marsh bird facing rapid population decline throughout its range, largely caused by degradation and loss of breeding habitat. Thus, there is a need to preserve tidal marshes in the northeastern United States, but to do so requires an understanding of the habitat features that support robust populations. Previous studies have shown Saltmarsh Sparrow abundance increases with marsh size, but in similar bird species, area sensitivity is more directly linked to edge avoidance. Whether additional landscape features affect the abundance of Saltmarsh Sparrows is unknown. We explored how the height of objects on the horizon, an index of habitat openness, affected the abundance of Saltmarsh Sparrows. Our primary goal was to determine whether the angle to the highest point on the horizon (“angle to maximum horizon”) predicted abundance better than marsh area or distance to the marsh edge. We used N-mixture models to evaluate the combination of spatial factors that best predicted Saltmarsh Sparrow abundance while also accounting for survey-level variables that could influence detection probability. We found that the interaction between distance to edge and angle to maximum horizon best predicted abundance. Taller objects on the horizon were negatively correlated with bird abundance, and this effect was strongest within 50 m of the marsh edge. When we considered the predictive powers of patch area, distance to edge, and angle to maximum horizon individually, angle to maximum horizon was the best single predictor. We found the highest abundance of Saltmarsh Sparrows at point locations where the angle to maximum horizon was 0.0°, and at angles greater than 12° the predicted abundance fell below 1 bird per survey point. We propose that managers should prioritize marsh openness and experimentally test the effect of marsh edge manipulations when making conservation decisions for this rapidly declining species.

Potential of Pléiades and WorldView-3 Tri-Stereo DSMs to Represent Heights of Small Isolated Objects.

High-resolution stereo and multi-view imagery are used for digital surface model (DSM) derivation over large areas for numerous applications in topography, cartography, geomorphology, and 3D surface modelling. Dense image matching is a key component in 3D reconstruction and mapping, although the 3D reconstruction process encounters difficulties for water surfaces, areas with no texture or with a repetitive pattern appearance in the images, and for very small objects. This study investigates the capabilities and limitations of space-borne very high resolution imagery, specifically Pléiades (0.70 m) and WorldView-3 (0.31 m) imagery, with respect to the automatic point cloud reconstruction of small isolated objects. For this purpose, single buildings, vehicles, and trees were analyzed. The main focus is to quantify their detectability in the photogrammetrically-derived DSMs by estimating their heights as a function of object type and size. The estimated height was investigated with respect to the following parameters: building length and width, vehicle length and width, and tree crown diameter. Manually measured object heights from the oriented images were used as a reference. We demonstrate that the DSM-based estimated height of a single object strongly depends on its size, and we quantify this effect. Starting from very small objects, which are not elevated against their surroundings, and ending with large objects, we obtained a gradual increase of the relative heights. For small vehicles, buildings, and trees (lengths <7 pixels, crown diameters <4 pixels), the Pléiades-derived DSM showed less than 20% or none of the actual object’s height. For large vehicles, buildings, and trees (lengths >14 pixels, crown diameters >7 pixels), the estimated heights were higher than 60% of the real values. In the case of the WorldView-3 derived DSM, the estimated height of small vehicles, buildings, and trees (lengths <16 pixels, crown diameters <8 pixels) was less than 50% of their actual height, whereas larger objects (lengths >33 pixels, crown diameters >16 pixels) were reconstructed at more than 90% in height.

New Heights of the Highest Peaks of Polish Mountain Ranges

The idea to verify the height of the highest peaks (summits) in the Crown of Polish Mountains arose after analyzing sources regarding the date and method of measuring the height of these mountain peaks. Our investigations revealed that this type of material is not usually available, and the first mention of height values is most often noted in the inter-war period, and occasionally before WWI (when Poland did not exist as an independent state); most of these values are still in use to this day. The problem of accurate measurement of the height of mountain peaks concerns not only the peaks analyzed by the authors, but also almost all mountain peaks worldwide. Therefore, as part of this work, several trips were organized to the highest peaks of several dozen mountain ranges in the territory of Poland. Measurement was made using a precise geodetic GNSS receiver an accuracy of within 10 cm and a DTM model based on ALS (airborne laser scanning). The results showed that commonly published heights can differ by up to several meters from the actual ones. The most important element of this work consists of the establishment of new measurements of the heights of the highest peaks of all mountain ranges in Poland, which may result in an alteration of the officially recorded heights based on this article. Apart from verification of these heights, this work also aimed to address the issue of the heights of all characteristic objects whose heights must be verified by using modern satellite techniques.

Seidel primary ray aberration coefficients for objects placed at finite and infinite distances.

In a recent study, the present group proposed a methodology for determining the Seidel primary aberration coefficients in terms of the polar coordinates of the source ray for an object placed at a finite distance from the entrance pupil [P. D. Lin and R. B. Johns, Opt. Express27, 19712 (2019)]. However, that model will be failed for an object placed at infinity. It is also found that all existing works in the optics field use in-plane coordinates of the entrance pupil (i.e., Xa and ya) to investigate the aberration coefficients. Accordingly, the present study revisits the problem once again using a Taylor series expansion of a ray in terms of the object height h0 and coordinates [xaya]T. In the proposed methodology, the independent variables of the optical system are identified and the intercept coordinates of the skew ray on the image plane are then expanded with respect to these variables. It is shown that the expressions of the Seidel primary aberration coefficients are very concise and the corresponding numerical results are in good agreement with those obtained from Zemax simulations. Notably, the method proposed in this study is also valid for objects lying at infinity provided that the collimated rays emerging from the object are incident on the entrance pupil. Moreover, the methodology can also be extended to have the numerical values of the higher-order ray aberration coefficients for axis-symmetrical systems.