Photogrammetric modeling of underwater environments

Underwater photogrammetry provides an efficient nondestructive means for measurement in environments with limited accessibility. With the growing use of consumer cameras, its application is becoming easier, thus benefiting a wide variety of disciplines. However, utilizing cameras for underwater photogrammetry poses some nontrivial modeling problems due to refraction effect and the extension of the imaging system into a unit of both the camera and the protecting housing device. This paper studies the effect that the underwater environment has on the photogrammetric process, and proposes a model for describing the geometric distortions and for estimating the additional parameters involved. The proposed model accounts not only for the multimedia effect, but also for inaccuracies related to the setting of the camera and housing device. The paper shows that only a small number of additional parameters is needed to model both elements and to preserve the collinearity relation. The results show that no unique setup is needed for estimating the additional parameters and that the estimation is insensitive to noise or first approximations. Experiments show that high levels of accuracy can be achieved.     

南巴伦支海磁场异常及其与海底地质结构的对比(英文)

对1986—2001年间巴伦支海南部海洋磁力测量的数据处理结果进行了研究。南巴伦支海底的地磁测量揭示出其复杂多期的地质构造结构,其中以两期分离型的构造为主导:(1)具NW走向的里菲-文德期继承性裂谷构造;(2)NE向转换叠加断层正交系统。晚泥盆世碱性侵入体及其相关的金属矿化作用恰位于这些构造系统的交点上。     

Sinkhole characterization in the Dead Sea area using airborne laser scanning

Since the early 1980s, the Dead Sea coast has undergone a near catastrophic land deterioration as a result of a rapid lake-level drop. One conspicuous expression of this deterioration is the formation of sinkholes fields that puncture the coastal plains. The evolution of sinkholes along nearly 70-km strip has brought to a halt the regional development in this well-known and toured area and destroyed existing infrastructures. Great efforts are being invested in understanding the phenomena and in development of monitoring techniques. We report in this paper the application of airborne laser scanning for characterization of sinkholes. We demonstrate first the appropriateness of laser scanning for this task and its ability to provide detailed 3D information on this phenomenon. We describe then an autonomous means for their extraction over large regions and with high level of accuracy. Extraction is followed by their detailed geometric characterization. Using this high-resolution data, we show how sinkholes of 0.5 m radius and 25 cm depth can be detected from airborne platforms as well as the geomorphic features surrounding them. These sinkhole measures account for their embryonic stage, allowing tracking them at an early phase of their creation.     

ANALYSIS OF Cu, Cd, Co AND Ni IN SURFACE WATER OF THE KUROSHIO AREA IN THE EAST CHINA SEA

Study of 1986 and 1987 heavy metal distribution in surface water of the Kuroshio area in the East China Sea showed regional and slight seasonal variations in distribution and concentration . Heavy metal levels in Taiwan Strait, the sea area north of Taiwan and the continental shelf are higher than those in the main axis of the Kuroshio . Dissolved Cu in summer and winter decreases with the increase of salinity , but dissolved Cd has no obvious change with salinity .     

New data about the structure of the anomalous magnetic field in the central part of the Kuril-Kamchatka island arc

New data about the structure of the anomalous magnetic field in the central part of the Kuril-Kamchatka island arc were obtained during cruise 37 of R/V Akademik Lavrent’ev in 2005. In order to study the deep geological and tectonic structure of this seismically hazardous area, calculations of the depths of the sources of magnetic anomalies with the use of the method of space-frequency analysis of the field were carried out. Transformations of the magnetic field were executed and a part of the samples dredged were petromagnetically examined. An analysis of the data obtained suggests the mainly block-wise structure of the research area. The fracture zones that border the blocks were recognized; the width of the tectonic blocks varies from 10 to 100 km. The most typical extension of the blocks is 25–30 km. In the central part of the region, an extensive V-shaped zone of a negative anomalous field is distinguished together with conjugated intensive positive magnetic anomalies that represent the boundaries of a tentative zone of extension. At the flanks of this zone and on its central rise, areas of manifestations of volcanic activity are outlined.     

Analysis of the geomagnetic field of the White Sea: The Gorlo Strait

The objective of our research is the interpretation of the results of the geomagnetic survey of the geologic structure in the Gorlo Strait of the White Sea. We used the maps of the anomalous magnetic field (AMF) available and processed them with original interpretation software. As a result of this processing, we compiled a structural-tectonic chart of this region. We distinguished the boundaries of the major first-order tectonic structures such as the underwater extension of the Leshukon graben and a number of minor structures related to the Proterozoic and Paleozoic stages of the magmatic activity in the region. Modeling was performed for the most important objects, which allowed us to refine the geological structure of these objects and their genesis.     

Associations of Meteor Microshowers or as the Kazan Radar “SEES” Radiants on Northern Celestial Hemisphere

The discrete quasitomographic method of the analysis of the interferometric data of meteor radar gives us the possibility of measuring coordinates and velocities of very weak meteor showers with a 2 × 2 square degree resolution on the celestial sphere. The minimal rate of the meteors in each microstream is five meteors per day. At such sensitivity, basic distinctions between irregularities of the sporadic background and meteor streams vanish. More than 1000 of the detected microshowers per month are associated with a combination of (a) the large known meteor showers, (b) the weaker known meteor showers and (c) till now unknown associations of microshowers. All microshowers regardless of association have the identical velocities, limited areas of radiation and near simultaneity of their acting dates. The results are compiled as maps of radiant distribution and average velocities of microstreams for different months. From these it is possible to see how the microshower activity for various discrete sites on the celestial sphere correlate with the behavior of the well-known meteor streams and thus to infer the orbital properties of the different microstream configurations.     

Detection of gullies in roughly textured terrain using airborne laser scanning data

Airborne laser scanning data contain information about surface features, some of which are of subtle form. These features are usually embedded within the terrain, and rarely form distinct shape-transition to their surroundings. While some efforts have been made in extracting linear elements from laser scanning data, attention was mostly turned to dominant elements that are very clear and distinct. We present in this paper a detection model for gullies of various dimensions using airborne laser scanning data. Gullies are regarded as one of the main landform-reshaping agents, having a pejorative effect on the environment and on regional development. They are commonly observed along receding lakes as a common response to water-level drop. The paper demonstrates how a multi-scale approach enables the extraction of various gully forms, from well developed to subtle. It then proposes an optimization driven model for handling fragmentation in the detection. Results show that using the proposed model, gully networks can be reconstructed and ∼30 cm deep features can be identified and separated from their surroundings using moderate point density data.     

http://www.sciencedirect.com/science/article/pii/S1674987112000849

New methods are presented for processing and interpretation of shallow marine differential magnetic data,including constructing maps of offshore total magnetic anomalies with an extremely high resolution of up to 1-2 nT,mapping weak anomalies of 5-10 nT caused by mineralization effects at the contacts of hydrocarbons with host rocks,estimating depths to upper and lower boundaries of anomalous magnetic sources,and estimating thickness of magnetic layers and boundaries of tectonic blocks. Horizontal dimensions of tectonic blocks in the so-called "seismic gap" region in the central Kuril Arc vary from 10 to 100 km,with typical dimensions of 25-30 km.The area of the "seismic gap" is a zone of intense tectonic activity and recent volcanism.Deep sources causing magnetic anomalies in the area are similar to the "magnetic belt" near Hokkaido. In the southern and central parts of Barents Sea,tectonic blocks with widths of 30-100 km,and upper and lower boundaries of magnetic layers ranging from depths of 10 to 5 km and 18 to 30 km are calculated.Models of the magnetic layer underlying the Mezen Basin in an inland part of the White Sea-Barents Sea paleorift indicate depths to the lower boundary of the layer of 12-30 km.Weak local magnetic anomalies of 2-5 nT in the northern and central Caspian Sea were identified using the new methods,and drilling confirms that the anomalies are related to concentrations of hydrocarbon.Two layers causing magnetic anomalies are identified in the northern Caspian Sea from magnetic anomaly spectra.The upper layer lies immediately beneath the sea bottom and the lower layer occurs at depths between 30-40 m and 150-200 m.     

Orbital structure of the meteor complex according to radar observations in Kazan. 1. Apparent distributions of aphelia

The results of an analysis of the orbital structure of the meteor complex accessible for radar observations at northern midlatitudes are reported. Experimentally, the study is based on the long-term monitoring of the influx of meteor matter into the Earth’s atmosphere performed with the meteor radar of Kazan State University starting from 1986. The study uses a discrete quasi-tomographic method to measure the radiants and velocities of meteor showers based on goniometric data of the meteor radar and diffraction measurements of meteor velocities. The discretization of the detection environment—in particular, in terms of velocity—is shown to result in no substantial loss of measurement accuracy. The error of the measured velocity of the shower does not exceed 1.5 km/s for a standard deviation of a single velocity measurement equal to 3 km/s. Microshower representation is used with microshowers either representing the correlated part of the sporadic complex or being partial streams of major and minor showers, or fragments of the dust environment of minor bodies passing by Earth or falling onto it. The data of measurements made over the entire annual cycle are used to construct combined maps of the distribution of the observed 2263 microshowers (a total of 22 604 orbits) by their inclination, aphelion distance, and longitudes of the ascending nodes of their orbits. The observing conditions are shown to have a significant effect on the parameters of the distribution of aphelion distances for different months, and the corresponding distributions for prograde and retrograde orbits are shown to differ fundamentally. A specific feature of such distribution maps is that they allow uniform representation of both meteor showers and irregularities of the sporadic complex.