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The CartoDEM Version 3 Release 1 openly accessible datasets are currently the most reliable datasets for relatively plain regions in India specifically. The aim of the presented study is to evaluate CartoDEM with respect to two openly accessible spaceborne LiDAR datasets from two LiDAR sensors: the Advanced Topographic Laser Altimeter System (ATLAS) on board the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) and Global Ecosystem Dynamics Investigation (GEDI) over the International Space Station (ISS). The differences and deviations were computed for CartoDEM and LiDAR footprint elevations for the two datasets, namely, ICESat-2 and GEDI. The difference values were filtered for footprints with differences between 0 and 2.5 in the DEM and LiDAR elevation values. Besides this, an overall estimate was also calculated for the elevation values obtained over the surface, i.e., the ground, as well as objects such as the trees or buildings. The RMSEs were observed to be 1.16 m and 1.74 m for the ICESat-2 and GEDI datasets for the points/footprints on the terrain, whereas when considering similar parameters for the two datasets, the RMSEs were found to be 1.78 m and 5.48 m for the ICESat-2 and GEDI footprints on the surface (terrain/object), respectively. This study reveals that CartoDEM is highly accurate in the plain regions when validated with respect to the ICESat-2 datasets, which work via the photon counting technique. Further, it was observed that ICESat-2’s performance is better than that of the GEDI mission for terrain height. Thus, it was observed that the spaceborne LiDAR datasets from ICESat-2 can be utilized for the validation of DEMs and can be useful for applications where an input to a DEM is required for engineering or modeling applications.

The article talks about the plans of Kazakhstan to develop its own national space industry and plans to build new launch and tracking facilities at Baikonur and a constellation of Kazakh communication satellites. The country's motivation has been part financial, improving satellite systems that would support economic growth, and as Russia has found, the capability to launch commercial satellites generates income. Government officials plan to configure the new Baiterek launch complex to launch only Russian-made Angara rockets, whose fuels is more environmentally friendly.

This paper reviews the combined video meteor spectroscopic observations of the Kilwinning Spectroscopic Survey for Meteors (KiSSMe) and the related mutual capture, multi-video station orbital observations from the Network for Meteor Triangulation and Orbit Determination group (NEMETODE) in the period between 201S April and 2016 April.A total of eleven mutual events were captured. A brief comment is made about the main lines in each spectrum and orbital elements are presented for eight of the meteors. [ABSTRACT FROM AUTHOR]

In triangulation (or angle of arrival) target localisation method, the surface of the Earth is approximated by a flat plate. This approximation, while acceptable for low-altitude observers (such as unmanned aerial vehicles), is not a correct model for high-altitude observers (such as low Earth orbit - LEO satellites). In this study, the authors have discussed triangulation method using a LEO satellite observer over a spherical surface and have shown that, using spherical trigonometry and singular value decomposition (SVD), a straight forward solution can be found for target localisation problem. Also, error bound is discussed and analysed using both SVD as well as simulation. [ABSTRACT FROM AUTHOR]

Ambient intelligence is a new information paradigm, where people are empowered through a digital environment that is “aware” of their presence and context and is sensitive, adaptive, and responsive to their needs. Hence, one of the important requirements for ambient intelligent environments (AIEs) is the ability to localize the whereabouts of the user in the AIE to address her/his needs. In order to protect user privacy, the use of cameras is not desirable in AIEs, and hence, there is a need to rely on nonintrusive sensors. There are various localization means that are available for outdoor spaces such as those which rely on satellite signals triangulation. However, these outdoor localization means cannot be used in indoor environments. The majority of nonintrusive and noncamera-based indoor localization systems require the installation of extra hardware such as ultrasound emitters/antennas, radio-frequency identification (RFID) antennas, etc. In this paper, we propose a novel indoor localization system that is based on WiFi signals which are free to receive, and they are available in abundance in the majority of domestic spaces. However, free WiFi signals are noisy and uncertain, and their strengths and availability are continuously changing. Hence, we present a fuzzy logic-based system which employs free available WiFi signals to localize a given user in AIEs. The proposed system receives WiFi signals from a large number of existing WiFi access points (up to 170 access points), where no prior knowledge of the access points locations and the environment is required. The system employs an incremental lifelong learning approach to adjust its behavior to the varying and changing WiFi signals to provide a zero-cost localization system which can provide high accuracy in real-world living spaces. We have compared our system in both simulated and real environments with other relevant techniques in the literature, and we have found that our system outperforms the other systems in the offline learning process, whereas our system was the only system which is capable of performing online learning and adaptation. The proposed system was tested in real-world spaces from a living lab intelligent apartment (iSpace) to a town center apartment to a block of offices. In all these experiments, our system has been highly accurate in detecting the user in the given AIEs, and the system was able to adapt its behavior to changes in the AIE or the WiFi signals. We envisage that the proposed system will play an important role in AIEs, especially for privacy concerned situations like elderly care scenarios. [ABSTRACT FROM AUTHOR]

The article highlights satellite tracking in South Africa from 1957-1958. A project called MOONWATCH was organized and coordinated by the Smithsonian Astrophysical Observatory in Massachusetts for amateur observers in South Africa. After the country was discovered to be the first land mass to be crossed by a satellite after being launched in Florida, observing sites were established in Johannesburg and Pretoria. The several satellites observed from South Africa are presented.

We investigate how coronal mass ejections (CMEs) propagate through, and interact with, the inner heliosphere between the Sun and Earth, a key question in CME research and space weather forecasting. CME Sun-to-Earth kinematics are constrained by combining wide-angle heliospheric imaging observations, interplanetary radio type II bursts, and in situ measurements frommultiple vantage points.We select three events for this study, the 2012 January 19, 23, and March 7 CMEs. Different from previous event studies, this work attempts to create a general picture for CME Sun-to-Earth propagation and compare different techniques for determining CME interplanetary kinematics. Key results are obtained concerning CME Sun-to-Earth propagation: (1) the Sun-to-Earth propagation of fast CMEs can be approximately formulated into three phases: an impulsive acceleration, then a rapid deceleration, and finally a nearly constant speed propagation (or gradual deceleration); (2) the CMEs studied here are still accelerating even after the flare maximum, so energy must be continuously fed into the CME even after the time of the maximum heating and radiation has elapsed in the corona; (3) the rapid deceleration, presumably due to interactions with the ambient medium, mainly occurs over a relatively short timescale following the acceleration phase; and (4) CME–CME interactions seem a common phenomenon close to solar maximum. Our comparison between different techniques (and data sets) has important implications for CME observations and their interpretations: (1) for the current cases, triangulation assuming a compact CME geometry is more reliable than triangulation assuming a spherical front attached to the Sun for distances below 50–70 solar radii from the Sun, but beyond about 100 solar radii we would trust the latter more; (2) a proper treatment of CME geometry must be performed in determining CME Sun-to-Earth kinematics, especially when the CME propagation direction is far away from the observer; and (3) our approach to comparing wide-angle heliospheric imaging observations with interplanetary radio type II bursts provides a novel tool in investigating CME propagation characteristics. Future CME observations and space weather forecasting are discussed based on these results. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an innovative image matching method for reliable and dense image matching on poor textural images, which is the integrated point and edge matching based on the self-adaptive edge-constrained triangulations. Firstly, several seed points and seed edges are obtained on the stereo images, and they are used to construct a pair of initial edge-constrained triangulations on the images. Then, points and edges are matched based on the triangle constraint and other constraints. The newly matched points and edges are inserted into the triangulations and the constrained triangulations are updated dynamically along with the matching propagation. The final results will be the final edge-constrained triangulations generated from the successfully matched points and edges. Experiments using typical space-borne, airborne, and terrestrial images with poor textures revealed that the integrated point and edge matching method based on self-adaptive triangulations is able to produce dense and reliable matching results. Moreover, from the final matched points and edges, 3D points and edges preserving the physical boundaries of objects can be further derived based on photogrammetric techniques, which is ideal for further object modeling applications. [Copyright &y& Elsevier]

The article discusses the limitations and admissibility of using historical cellular site data to track the location of a cellular phone. It talks about the capability of cell site data to track cellular phone locations if enough information is available to perform triangulation. It tackles concerns on the accuracy of triangulation and proves the effectiveness of the interpretation of historical cell site data as a useful investigative tool.

The main obstacle to achieving high precision in georeferencing from high-resolution satellite imagery (HRsI) remains the need for provision of good quality ground control points (GCPS), whether the GCP5 are used to remove biases in RPC triangulation or to support physical sensor orientation models. The provision of GCP5 can be very costly and is often not feasible in remote regions, the very areas where mapping from satellite imagery shows significant potential. In order to drastically reduce the number of GCP5 required for georeferencing from HRSI, a generic sensor orientation model incorporating strip adjustment capability has been adopted. Under this approach, the metadata for each separate scene is merged to produce a single, continuous set of orbit and attitude parameters, such that the entire strip of tens of images can be treated as a single image. The merging of orbit data results in a considerable reduction in both the number of unknown parameters and the number of required GCP5 in the sensor orientation. RPC5 are then generated from the adjusted orientation data for each image forming the strip or block. Application of the method to very long strips of ALOS PRSIM imagery is reported in this paper. The results of experimental testing indicate that one-pixel level accuracy can be achieved over strip lengths of more than 50 ALOS images, or 1,500 km. with as few as four GGPs. [ABSTRACT FROM AUTHOR]

In this paper, we propose a segment-based triangulation method for building parallel-perspective stereo mosaics using ray interpolation. The currently available fast parallel ray interpolation for stereo mosaicing uses a uniform or regular triangulation technique that does not take advantage of the spatial information. This works well when the interframe displacement in the video is small. However, for large interframe displacements, hence large motion parallax, we observe visual artifacts in the mosaics when the source triangles in the video frames are warped into destination triangles in the mosaics using affine transformations. Our method uses the edge information present in the scene to ensure that triangles do not cross over from one planar facet to the other. The video frames are segmented, and the edges are obtained from the inner boundaries of different segments. A mesh is designed in each segment or region, over which motion between consecutive video frames is constant. Hence, this method avoids unwanted warping of objects with large motion parallax in the scene and reduces the visual artifacts. The performance of our proposed technique is demonstrated on a series of simple-to-complex video imagery collected by utilizing cameras and airborne sensors. [ABSTRACT FROM AUTHOR]

Many Spaceborne imagery products ore provided with metadata or support data having diverse types, representations, frequencies, and conventions. According to the variability of metadata, a compatible physical sensor model approach must be constructed. Among the three components of the sensor model, i.e., trajectory model, projection equations, and parameter subset selection, the construction of the position and attitude trajectory is closely linked with the availability and type of support data. In this paper, we show how trajectory models can be implemented based on support data from six satellite image types: QuickBird, Hyperion, SPOT-3, ASTER, PRISM, and EROS-A. Triangulation for each image is implemented to investigate the feasibility and suitability of the different trajectory models. The results show the effectiveness of some of the simple models while indicating that careful use of dense ephemeris information is necessary. These results are based on having a number of high quality ground control points. [ABSTRACT FROM AUTHOR]

The article focuses on a survey, conducted to investigate different wireless indoor positioning systems and to classify various techniques involved in the process of positioning. It reports that the systems have grown a lot recently and are being used in various applications including the inventory management and asset tracking. It analyzes the location estimation schemes of proximity, triangulation and scene assessment. It discusses location fingerprinting technique used in several positioning systems and examines the properties used in the evaluation of location systems. It evaluates and compares the performance of many positioning systems, commenting on their precision, scalability, accuracy, complexity, cost and robustness.

Abstract: Alfeld and Schumaker [Numer. Math. 57 (1990) 651–661] give a for mula for the dimension of the space of piecewise polynomial functions (splines) of degree d and smoothness r on a generic triangulation of a planar simplicial complex (for ) and any triangulation (for ). In Schenck and Stiller [Manuscripta Math. 107 (2002) 43–58], it was conjectured that the Alfeld–Schumaker formula actually holds for all . In this note, we show that this is the best result possible; in particular, there exists a simplicial complex such that for any r, the dimension of the spline space in degree is not given by the formula of Alfeld and Schumaker [Numer. Math. 57 (1990) 651–661]. The proof relies on the explicit computation of the nonvanishing of the first local cohomology module described in Schenck and Stillman [J. Pure Appl. Algebra 117 & 118 (1997) 535–548]. [Copyright &y& Elsevier]

We study non-crossing frameworks in the plane for which the classical reciprocal on the dual graph is also non-crossing. We give a complete description of the self-stresses on non-crossing frameworks G whose reciprocals are non-crossing, in terms of: the types of faces (only pseudo-triangles and pseudo-quadrangles are allowed); the sign patterns in the stress on G; and a geometric condition on the stress vectors at some of the vertices. As in other recent papers where the interplay of non-crossingness and rigidity of straight-line plane graphs is studied, pseudo-triangulations show up as objects of special interest. For example, it is known that all planar Laman circuits can be embedded as a pseudo-triangulation with one non-pointed vertex. We show that for such pseudo-triangulation embeddings of planar Laman circuits which are sufficiently generic, the reciprocal is non-crossing and again a pseudo-triangulation embedding of a planar Laman circuit. For a singular (non-generic) pseudo-triangulation embedding of a planar Laman circuit, the reciprocal is still non-crossing and a pseudo-triangulation, but its underlying graph may not be a Laman circuit. Moreover, all the pseudo-triangulations which admit a non-crossing reciprocal arise as the reciprocals of such, possibly singular, stresses on pseudo-triangulation Laman circuits. All self-stresses on a planar graph correspond to liftings to piecewise linear surfaces in 3-space. We prove characteristic geometric properties of the lifts of such non-crossing reciprocal pairs. [ABSTRACT FROM AUTHOR]

Shows how the Global Positioning System (GPS) functions. Distribution of multiple satellites in orbit around Earth; Concept of satellite triangulation; Parts of GPS; Categories for uses of system.

Abstract: The adoption of satellite imagery in archaeology is well recognized today, and is rapidly increasing with the greater availability of high resolution sensors, in the past limited solely to military applications. The metrical use of declassified satellite images from the intelligence CORONA project, the first US operational space photo reconnaissance project operating in the period 1960–1972, has been verified within the framework of a multidisciplinary research project carried out by the University of Bologna, in collaboration with Istanbul University and Gaziantep archaeological museum, at the archaeological site of Tilmen Höyük (south-eastern Turkey) and its surrounding landscape. These images, characterized by a panoramic geometry, indeed represent an important historical resource for photointerpretation in archaeology, but their metrical use is difficult, owing to the severe distortions affecting the acquisition together with the problems of finding technical data related to the missions. In order to produce metric products of sufficient quality for mapping purposes, a high resolution scanned copy of a CORONA image of the relevant area was processed using commercial digital photogrammetric workstations operating with different approaches, whose aim was to evaluate the potential and specific problems connected to these kinds of data. A full orientation and digital triangulation of these images is possible if all the technical data on the sensor and the acquisition are well-known, and in any case the existence of well-distributed and reliable ground control points in the study area is crucial. The results obtained are interesting as they allow for integration, on a common cartographic reference base, with current aerial and satellite imagery (medium to very high geometric resolution) to perform automatic or visual change analysis procedures. [Copyright &y& Elsevier]

Discusses historical surveys of several land areas in the Republic of Zambia. Overview of a classic triangulation survey from a 1954 boundery commission publication; Details of geodetic surveys between 1949 and 1964 including the establishment of triangulation nets and traverse loops; Grouping of the main areas of the primary control; Formation of a national cadastre for a land registration system; Transformation parameters for rotations from Arc datum to WGS84 Datum for Zambia.