RU2435136C1 - Method of measuring thickness of block of ice and apparatus for measuring thickness of block of ice - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of measuring thickness of a block of ice involves obtaining images of the block of ice using devices, analysing and interpreting the images, determining thickness of the block of ice via office processing of the images of the block of ice, where the image of the block of ice is obtained by probing ice surfaces with high-frequency acoustic waves, where continuous oscillation is amplitude-modulated by a section of a low-frequency signal, and the images are interpreted by forming a single set of coordinates of points and height values of each block of ice, obtained from the imaging devices, where the single set of coordinates and height values of the block of ice undergoes Delaunay triangulation.

EFFECT: high accuracy of measuring thickness of a block of ice.

Description

The invention relates to the determination of ice cover parameters by means of a device for measuring the thickness of ice floes mounted on a carrier and can be used both for research purposes and for monitoring the ice cover in regions where gas and oil deposits are located on the shelf of the Arctic seas.

A known method for determining the state of the ice cover (Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Alexandrov V.Yu., Frolov I.E. and other St. Petersburg, Nauka, 2007, p.68-71 [1]) consisting of visual ice observations from airplanes and helicopters of various types from altitudes of 100-600 m. When flying at these altitudes, the resolution of the human eye is assumed to be 0.1 m on the ground, which allows the observer to determine by the nature of the surface and, the state of the snow cover, the type of layering and hummocking, the thickness of the ice in the faults, the size and shape of the snowfields, the color shades of the surface of the ice, their debris, the bottom of the snowfields all the main characteristics of the ice cover - the position of the edge of the drifting and stationary ice, the concentration of ice, its age the composition, forms, layering and hummocking, stages of melting, the space of pure water among the ice, the height and nature of the snow cover, compression, contamination, the number and form of ice of mainland origin. In this case, observations are performed in the band from 19-20 flight altitudes (ice edges, boundaries of zones of different cohesion) to 2-3 altitudes (age composition), which is explained by different reliability and the possibility of determining certain characteristics at large viewing angles. Given the limited time of flight of each section, it is quite obvious that the observer cannot process the entire amount of information. Based on the results of observations, a working ice map is compiled. The method is burdened by significant random and systematic errors, restrictions on the span. In addition, when observing from low altitudes, only 10-20% of the surveyed water area is directly visible, which leads to significant errors in the interpolation and extrapolation of borders.

There is also a method of aerial photography of sea ice (Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Alexandrov V.Yu., Frolov I.E. and others. St. Petersburg, Nauka, 2007, pp. 72-76 [2]) using aerial cameras (AFA). Shooting is done in series over areas or routes.

The advantage of this method is the high resolution, geometric certainty of the images, which allows you to recreate the spatial model of the area and with a high degree of accuracy to determine the coordinates of the displayed points of the area, as well as the objectivity and uniqueness of the information received.

The disadvantage of this method is the dependence on weather and light; a large number of images and the complexity of their photochemical and photogrammetric processing; limited shooting areas from low altitudes; low efficiency in obtaining final results.

There is also a method for determining the state of ice cover by sensing sea ice using radar stations with a wavelength of 2-3 cm (Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Aleksandrov V.Yu., Frolov I.E. et al. St. Petersburg, Nauka, 2007, pp. 79-88 [3]) installed on airplanes and ships. In this case, the state of ice is determined through the effective dispersion area. This method allows you to perform an operational assessment of the state of ice cover in terms of age stages of ice and their private cohesion by gradation (young - annual - old ice). However, it is impossible to determine the stages of development of annual ice.

There are also known methods for determining the ice cover by sensing sea ice from artificial Earth satellites (Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Aleksandrov V.Yu., Frolov I .E. et al. St. Petersburg Science. 2007, p. 88-116 [4], Authors certificate SU No. 1788487 [5]), namely, that the ice cover is probed by satellite onboard equipment (side-scan radar, passive microwave multichannel scanning radiometer Radiometer with linear scanning by sphere or by angle). To obtain reliable information, as a rule, a combination of several devices is used, which is associated with a negative correlation of radiation intensity and electromagnetic wave scattering by ice of the same age at the frequencies used in the winter season. In the images of radar stations, old (two-year and many-year-old) ices give a strong scattered signal, and in the images of radiometric instruments - a weak intrinsic radiation. Young and annual ice, on the contrary, give a weak scattered signal and strong intrinsic radiation. It is this feature of combined images when combining data that allows recognizing one-year and perennial ice in the period of intense summer melting, open water at large scoops and wormwoods, as well as the position of the edge of the ice with an excited open water surface.

In the known method for determining the state of ice cover [5], which includes obtaining satellite radar images and images in the optical wavelength range, in order to increase reliability in determining the age and cohesion of ice in the spring-autumn period, the presence of warm front clouds zones according to the images in the optical wavelength range and, if it takes place, then re-radar survey is carried out under conditions corresponding to a complete change metrologist physical conditions in the study area.

In known methods, mapping procedures employ a method of visual analysis and interpretation of images, including quantitative estimates of the total and particular cohesion of ice, as well as interactive identification of the boundaries of ice zones using mosaics from multi-temporal images. In this case, mosaics are formed from previously normalized in brightness and transformed into a stereographic cartographic projection images from a radar station.

The main disadvantage of side-scan radars is that the resolution along the track is limited by the length of the antenna, which is compensated by the use of synthetic aperture radars. However, to identify sea ice and obtain stable results of sea ice mapping, it is necessary to choose various combinations of polarizations like AR, HH, HV, VV, VH at different ranges of sensing angles, which significantly increases the complexity, with little or no increase in the reliability of obtaining the final results.

Devices for directly measuring the thickness of ice floes are also known. The known device, which is a rail on the line, which is used for eye-tracking the thickness of ice on the ship (Instructions for observations of ice from a ship. L .: Sea transport - 1956. 53 p. [6]). Such a rail is a wooden board 50 cm long and 7-10 cm wide, divided into decimeters. Sections of a 1-meter long rail are alternately painted with white and black or white and red paints. A hole for the line is made in the middle of the rail, a button is knitted on the back of the rail. The essence of the application of this device is to throw the lath onto the ice, which serves to scale the visual determination of the thickness of the ice that rises on the edge at the side of the vessel. The disadvantage of this device is the low accuracy of determining the thickness of the ice.

Also known is the Tsurikov and Pervakov ice meter for determining the thickness of ice on the ship (Manuals for hydrometeorological stations and posts. Issue 9. Hydrometeorological observations at marine stations. Part III. Hydrometeorological observations made by navigational staff on marine vessels (observations of weather and sea conditions). L .: Gidrometeoizdat - 1966 [7]). The ice meter consists of a 60 cm long metal rod. A bracket with a short tube parallel to the rod is fixed at the end of the rod. A movable clamp with a support screw is mounted on the bar. A metal frame is attached to the clamp with a 14 × 22 cm transparent material plate inserted into it. A rectangular grid with divisions 2 cm across is applied to the plate. One grid division is divided into smaller divisions after 4 mm. The bar is marked with divisions after 1 cm; the zero of this scale coincides with the upper end of the tube, which is applied to the eye of the observer. A rubber eyecup is put on the tube, protecting the observer's eye from contact with the metal cooled at sea. The principle of measuring the thickness of ice with an ice gauge is based on the solution of such triangles, in which the large legs are the distance from the observer's eye to the measured object - turned on the edge of the ice and the distance from the eye to the frame, and the small legs are the measured thickness and its projection onto the grid.

The required ice thickness is found from the geometric ratio.

For measurements, the height of the observer's eye above the ice surface should be known. When the ice floe is on the beam, the number of grid divisions corresponding to the thickness of the ice floe is noticed. The disadvantage of this device is the rapid fatigue of the eyes during operation, which limits the amount of information received, as well as the significant complexity and low productivity.

A device for measuring the dimensions of atmospheric turbulent vortices is also known (Device for measuring the dimensions of atmospheric turbulent vortices. Utility Model Patent RU No. 566595 [8]), which comprises a digital camera configured to photograph an image in one simple operation and convert the photographed image to digital image data matrix, a processing device in the form of a personal or handheld computer, an image display device in the form of a printing device and / or a monitor containing an altimeter, a tilt angle meter, and a perspective distortion grid. In this device, the processing means is configured to create a perspective distortion grid depending on the output values of the altimeter and the tilt angle meter of the camera.

The disadvantage of this device is the need to obtain for each frame a separate grid of perspective distortions, which increases the amount of information stored, and also requires visual reports on the image.

Also known is a utility model aimed at expanding the functionality and improving the accuracy of measuring the size of ice floes (patent for utility model RU No. 70983 [9]).

The claimed technical result is achieved in that the device for measuring the thickness of the ice from the side of the vessel contains a television camera, the output of which is connected to the input of an analog-to-digital converter of the television video signal into a digital image data matrix, the output of which is connected to the processing device in the form of a personal or pocket computer, output which is connected to the image display device in the form of a monitor, and the input is connected to the manipulator for moving the light marker on the monitor screen.

In this case, the size of the ice is measured by calculating the distance between two markers on the images turned on the edge of the ice, for which purpose the composition of the known device includes a television camera, a digital-to-analog converter and a manipulator ("mouse", trackball, etc.), with which The image contains light markers marking the beginning and end of the interval. The known invention [9] is implemented by means of a television camera connected by a cable to an analog-to-digital converter, the signal from the output of which is sent via cable to the connector of the processing device, to the input connector of which data on the height of the camera on the bridge of the vessel are entered in the form of the corresponding signal. The processing device is connected to the monitor with a cable and to the cable manipulator.

Moreover, the known device [9] works as follows.

The television camera is placed on the bridge of the vessel in the position of sighting on the sea surface, and the values of the height above the sea surface and the angle of the optical axis of the camera are recorded. The signal about the corresponding data by means of data input devices, made in the form of a keyboard, is transmitted via cable to the input of the processing device. The digital signal of the perspective image in the form of a matrix of digital brightness values from the output of the analog-to-digital converter is sent via cable to the input of the processing device, which calculates the distance between the points formed on the monitor image in the form of light markers depending on the values of the height of the camera and the position of the elements of the matrix of the digital signal corresponding to the position of the markers. The image combined with the marker through the output as a signal enters the monitor screen onto the device. The digital matrix of the image signal and the distance between the markers - the size of the ice floes enter the data storage device on command from the information input device. A significant disadvantage of the known device is that to measure the thickness of the ice, it is necessary that the ice floes stand on the edge, which significantly reduces the applicability of the known device.

In addition, shooting ice from the side of the vessel requires the use of additional devices and devices to ensure stabilization of the television camera to obtain high-quality images, and also significantly reduces the shooting sector.

The objective of this technical solution is to increase the reliability of measuring the thickness of ice.

The problem is solved due to the fact that in the method of measuring the thickness of the ice, including obtaining images of ice using instrumentation, analyzing and interpreting images, determining the thickness of the ice, using in-camera processing of ice images, in contrast to the prototype, the image of ice is obtained by sensing ice surfaces with high-frequency acoustic waves, while the continuous oscillation is modulated in amplitude by a segment of a low-frequency signal, and the thickness of the ice floes is determined by the magnitude of the gap When the low-frequency signal reflected from the ice-air interface is in relation to the envelope of the signal reflected from the water-ice interface, when displaying the image on the monitor, two-dimensional and / or three-dimensional images of ice are constructed, while the observation point is constantly in the center of the monitor window, point The observation is visualized by a symbol in the form of a trihedron of axes, the beginning of which is the center of rotation of the image relative to which the image scene moves.

In the device for measuring the thickness of the ice from the side of the carrier containing the device for registering the image of the profile of the ice, a processing device in the form of a personal or pocket computer, the output of which is connected to a display device in the form of a monitor, an analog-to-digital converter of the recorded signals into a digital image data matrix, input which is connected to the output of the ice profile image registration device, and the output to the input of the processing device, unlike the prototype, the registration device and the ice profile image is made in the form of a parametric acoustic location tool, the personal computer is connected via the port to the receiver of the carrier’s satellite navigation system, the image display device contains an electronic map storage and playback unit, a module for constructing two-dimensional and / or three-dimensional ice images, the carrier being made in in the form of a rigid-frame airship equipped with an acoustic locator, satellite navigation receiver, laser scanning devices, aerial photos surveys and thermal imaging survey.

New distinctive features of the proposed method, namely, that the image of ice floes is obtained by sensing ice surfaces with high-frequency acoustic waves, while the continuous oscillation is modulated in amplitude by a segment of a low-frequency signal, and the thickness of the ice is determined by the delay value of the low-frequency signal reflected from the ice-air interface , in relation to the envelope of the signal reflected from the water-ice boundary, when displaying the image on the monitor, two-dimensional and / or dimensional image of ice floes, while the observation point is constantly in the center of the monitor window, the observation point is visualized with a symbol in the form of a trihedron of axes, the beginning of which is the center of rotation of the image relative to which the image scene moves, they allow to achieve the claimed technical result, which consists in increasing the reliability of measuring the thickness of the ice .

A device for measuring the thickness of ice from the carrier, through which the proposed method is implemented, comprises an ice profile image registration device, a processing device in the form of a personal or pocket computer, the output of which is connected to an image display device in the form of a monitor, an analog-to-digital converter of the recorded signals to digital image data matrix, the input of which is connected to the output of the ice profile image registration device, and the output - with the input of the image device the backbone, and unlike the prototype, the device for recording the profile image of ice floes is made in the form of a parametric acoustic location tool, a personal computer is connected via a port to a receiver of the satellite navigation system of the carrier, the image display device contains an electronic map storage and playback unit, a two-dimensional and / or module for constructing a three-dimensional image of ice floes, while the carrier is made in the form of a rigid-frame airship equipped with an acoustic locator, satellite navigation receiver gatsii, laser scanning devices, aerial photography and thermal recording.

The carrier of the device for measuring the thickness of ice floes is a rigid-frame airship, also equipped with a satellite navigation system, laser scanning devices, aerial photography and thermal imaging, an analog of which is the airship listed in the information source: A. Frolov. Airships in the Gazprom system. The corporate magazine of Gazprom (www.GAZPROM.RU). No. 6, 2009, pp. 40-41.

The device for measuring ice thickness is an acoustic locator, the principle of which is based on the pulsed method of ice positioning (Linearisierung des Schreibermasstabes vom Seitensicht - Sonar. Kilian Zech, Marszal Tacek / Wiss. Z. Wik / Ihelm-Pieck-Univ. Rostok, Naturwiss. R., 1986. - V.34, No. 3, p. 36-40).

In contrast to the well-known pulsed methods of ice location, this method is implemented with continuous high-frequency radiation. In this case, in contrast to the methods used for ice location, in which high-frequency sound vibrations (100 kHz and higher) are used to ensure high resolution, a method based on nonlinear or parametric effects is used (V.A. Voronin, S.P. Tarasov, V.I. Timoshenko, Hydroacoustic Parametric Systems (Rostov-on-Don, Rostizdat LLC, 2004, pp. 11-42), due to the fact that the direct application of the known frequency range for measuring ice thickness is difficult due to acoustic attenuation ox n in the thickness of the ice.

To eliminate this drawback in a specific technical implementation of an acoustic locator, continuous oscillation is modulated in amplitude by a low-frequency signal segment, and due to nonlinear effects, a low-frequency wave propagates in ice. The thickness of the ice is determined by the delay value of the low-frequency signal reflected from the ice-air interface with respect to the envelope of the signal reflected from the water-ice interface.

Based on the measurement results, a digital model of the studied ice topography is built.

In addition to the obtained measurement results, source data for creating a digital model of ice relief (DEM) can be topographic maps when conducting research in the coastal zone, aerial photographs, satellite images, altimetry measurements, and marine navigation charts.

At the same time, the following DTM construction technology was adopted (Suvorov S.G., Dvoretsky E.M., Kovalenko S.A. Methodology for creating digital elevation models of high accuracy. // Information and space. No. 1, 2005 - p. 52-54) .

All available information is digitized. The data obtained from various sources are combined into a single set of coordinates of points and heights in them. This set is triangulated (Delaunay method). The triangulation procedure gives a system of disjoint triangles covering the considered region of the earth's surface (TIN model). As a result, the relief appears as a multifaceted (elementary face - a triangle) surface with elevations (depth marks) at the nodes of the triangular network. Each face of this surface is described either by a linear function (polyhedral model) or by a polynomial surface, the coefficients of which are determined by the values at the vertices of the triangle faces. This technology in various versions is implemented in all geoinformation systems used in practice.

When visualizing the measurement results, the navigation system is constructed using the principle of organizing the observation point of a three-dimensional scene, which is alternative to the well-known GA type technology, in which the standard principle is used - the observation point is located outside the scene and the scene is stationary during navigation, and the coordinates of the observation point and the viewing angle are changed. In this case, the center of rotation is not clearly determined, which is one of the reasons for the loss of image during navigation. In the proposed technology, the observation point is constantly in the center of the observation window and is visualized by a small trihedral of axes, and the beginning of the trihedron is always the center of rotation of the image, and when navigating the scene moves relative to this center.

The personal computer is an industrial microcomputer with a liquid crystal display and the necessary software based on the ATMEC family of microprocessors from the A8rR family. The receiver of the satellite navigation system through the port is connected to a microcomputer. Electronic navigation charts for the required research area are displayed on the monitor when conducting research in water areas equipped with geographic landmarks, natural or artificial, with known coordinates, which allows you to determine the position of the ice with reference to the coordinates.

The presence of laser scanning, aerial and thermal imaging devices on board the carrier also makes it possible to carry out an operational assessment of the state of the ice cover, in terms of age stages of ice and their private cohesion by gradation (young - one-year-old ice).

The main nodes and elements of the proposed device have industrial applicability, and the main technical methods, the implementation of the method have practical implementation.

Information sources

1. Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Alexandrov V.Yu., Frolov I.E. et al. St. Petersburg, Nauka, 2007, p. 68-71.

2. Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Alexandrov V.Yu., Frolov I.E. et al. St. Petersburg, Nauka, 2007, pp. 72-76.

3. Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Alexandrov V.Yu., Frolov I.E. et al. St. Petersburg, Nauka, 2007, pp. 79-88.

4. Scientific research in the Arctic. Volume 3. Remote sensing of sea ice on the northern sea route: study and application / Johannessen OM, Alexandrov V.Yu., Frolov I.E. et al. St. Petersburg, Nauka, 2007, p. 88-116.

5. Copyright certificate of the USSR No. 1788487.

6. Instructions for observing the ice from the ship. L .: Sea transport - 1956.53 s.

7. Instructions to hydrometeorological stations and posts. Issue 9. Hydrometeorological observations at marine stations. Part III. Hydrometeorological observations made by the navigational staff on marine vessels (observations of weather and sea conditions). L .: Gidrometeoizdat - 1966.

8. Patent for utility model RU No. 566595.

9. Patent for utility model RU No. 70983.

Claims (1)

A method of measuring the thickness of ice, including obtaining images of ice using instrumentation, analyzing and interpreting images, determining the thickness of ice using a cameral processing of ice images, characterized in that the image of ice is obtained by sensing ice surfaces with high-frequency acoustic waves, while the continuous oscillation is modulated by amplitude low frequency signal, and image interpretation is performed by forming a single set of coordinates of points and heights to every ice floe received from the ice image instrumentation equipment, and a single set of coordinates of points and ice heights is triangulated by the Delaunay method.