RU2519269C1 - Method of surveying bottom topography of water area and apparatus therefor - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: unlike the existing method, the present method includes, while emitting hydroacoustic signals towards the bottom, performing magnetic survey using a gradient metre which is towed 5 m from the bottom, seismoacoustic profiling using a profile recorder with operating frequency of 3.5 kHz, measuring the sea level, when processing depth measurements, further performing linear interpolation of the obtained bottom surface through triangulation, when mapping the obtained information with determination of geodesic coordinates of the depth measurements, evaluating the degree of spatial homogeneity of coverage of the survey region by measurement points by determining outer boundaries (contour) of the survey region using the apparatus for surveying the bottom topography of the water area, which consists of a transceiving antenna, a transmitting unit, a receiving-measuring unit, a control unit, a unit for determining the average speed of sound in water, a unit for collecting and processing information and mapping the bottom topography, a multibeam echo sounder, a unit for imaging the region of the bottom topography, a hydroacoustic Doppler log, a satellite navigation system receiver, a heading system, a roll measuring device, characterised by that the apparatus for surveying the bottom topography further includes a towed gradient metre, a profile recorder and a sea level metre, connected by their outputs to the inputs of the unit for collecting and processing information and mapping the bottom topography.

EFFECT: broader functional capabilities while increasing reliability and information value when mapping the bottom topography of a water area based on depth measurements using a multibeam echo sounder.

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Description

The invention relates to hydrography, in particular to methods and technical means for barometric surveying of the bottom topography by determining depths in a given water area and determining their geodetic coordinates.

A known method of shooting the topography of the bottom of the water surface with an echo sounder (Kolomiychuk ND Hydrography. L., GUNiO MO USSR, 1988, p.240-277 [1]), including the passage of a vessel with an echo sounder installed on it given tacks in the water area, the emission of hydroacoustic signals towards the bottom, receiving signals reflected from the bottom, measuring distances from the sonar receiving emitting antenna to the reflecting surface (bottom points), determining the ship's geographic coordinates, determining the geodetic coordinates of the sonar receiving emitting antenna, measuring the airborne parameters, kil eva and vertical pitching, the true heading and speed of the vessel, the determination of the true depths and their geodetic coordinates with their subsequent registration and display.

Also known is a device for implementing this method, which is an echo sounder (Hare R. Depth and position error budgets for multibeam echosounding // International Hydrographic Review. 1995, v. LXXII, No. 2, p. 37-69 [2]), containing a transceiver an antenna, a transmitting unit, a receiving-measuring unit, a control unit, a registration unit for processing the bottom topography, in which the output of the receiving-emitting antenna is connected to the input of the receiving-measuring unit, the output of the transmitting unit is connected to the receiving-radiating antenna, the outputs of the receiving-radiating unit are connected to the input of the registration unit, о processing and mapping of the bottom topography, the inputs of which are connected to the outputs of ship gauges of components of pitching, heading, speed and coordinates, and the control unit is connected to a transmitting unit, a receiving and measuring unit and a unit for collecting information, processing and mapping of the bottom topography.

Significant disadvantages of the known method and device are the relatively low accuracy of shooting the topography of the bottom of the water area, which does not meet the requirements for hydrographic surveying, as well as the significant complexity of the method, which is due to the need to perform calculations related to determining corrections for the deviation of the actual average speed of sound in water from used in the calculation of the calculated values of the average speed of sound in water for a particular echo sounder, which is determined indirectly fired by the measured values of the temperature, salinity and sea water density at the accepted practice in standard horizons in depth or by direct measurement of the sound velocity in a uniformly distributed points throughout the water area.

Due to the fact that the required reliability of determining the average speed of sound, performed by calculation, is provided only in a small local spatial area in which the temperature, salinity and density of sea water are measured or directly the speed of sound propagation in water for a particular echo sounder, the accuracy of shooting the bottom topography is the result is aggravated by the error due to the influence of small-scale and large-scale variability in time of wind displacement and turbulence of internal waves, odvodnyh currents. This error can reach 3% of the measured depth (see, for example: DE Dinn, BD Loncarevic et al. The effect of so und velocity errors on multibeam sonar depth accuracy // Proceedings of American Hydrograhic Symposium. 1995, p.1001-1009 ) In accordance with the requirements of the standard of the International Hydrographic Organization (see, for example: Notes on hydrography. St. Petersburg, GUNiO of the Ministry of Defense of the Russian Federation, No. 248.1999, p. 27-32) in water areas with depths exceeding 200 m, where shooting is carried out in the interests of safety of navigation, the mean square error (SEC) of determining the depth should not exceed 0.3%.

When using the known method of shooting a relief and a device for its implementation, the UPC determines the depth for depths up to 100 m from 0.7 to 3.5 m, and for depths up to 200 m from 2.3 to 11.0 m, respectively, which does not satisfy the requirements.

When mapping the bottom topography of the UPC, the bottom topography should not exceed 0.5 mm on the tablet scale, which, in combination with the error in determining the depth by a known method and device for its implementation, in most cases does not make it possible to provide this requirement.

In addition, when surveying the bottom topography with subsequent mapping of the bottom topography, especially in the coastal zone of the sea and in the narrowness, it is necessary to have cartographic information both by land and by the adjacent water area. The use of typographic topographic and navigation maps for these purposes is quite difficult. One of the reasons for this is different cartographic projections. Topographic maps are built in the Gauss-Krueger projection, and navigation maps in the Mercator projection. The same reason is the main obstacle to the use of raster images of printing cards in electronic geographic information systems, which are the means of displaying the mapped information when shooting the bottom topography.

There is also known a method of capturing the topography of the bottom of the water area and a device for its implementation (patent RU No. 2340916 [3]), in which the technical result, which consists in increasing accuracy, is solved due to the fact that the method of shooting the topography of the bottom of the water area with an echo sounder installed on the vessel, including radiation of hydroacoustic signals in the direction of the bottom, receiving signals reflected from the bottom surface, measuring distances from the receiving-emitting antenna to the bottom, determining the coordinates of the vessel from external sources of information, measuring onboard, keel and vert pitching, true heading and speed of the vessel, referencing the measurement results in time, determining the true depths with the correction for the deviation of the actual speed of sound in water from the calculated one, mapping the received information with determining the geodetic coordinates of the measured depths, in which the correction for true depths the deviation of the actual speed of sound in water from the calculated one is determined taking into account the Doppler frequency shift between the emitted and reflected hydroacoustic signals sonar lag from the seabed, when mapping the topography of the bottom perform pairing of topographic and navigation raster maps.

This method due to the fact that when determining the true depths, the correction for the deviation of the actual speed of sound in water from the calculated one is determined taking into account the average speed of sound propagation in water through the values of the Doppler frequency shift between the emitted and reflected hydroacoustic signals of the hydroacoustic lag from the seabed, allows to achieve a technical result , which consists in increasing the accuracy of shooting the relief of the bottom of the water area. However, due to the fact that the survey is carried out by means of measuring equipment installed on a surface vessel subject to the influence of external conditions, the so-called faulty data are present during the survey, which are rejected during the final processing of the measured information. The presence of bad data increases the shooting time, and, accordingly, the complexity of processing.

The introduction of corrections envisaged in analogs, depending on the current values of yaw, roll, and trim of the measuring instrument carrier, also does not fully eliminate the errors in measuring the depths of the water area, both due to the large inertia of the sensors and due to uneven energy loss not only along the path from the vibrator to bottom and at the bottom (due to incomplete reflection), but also on the way back.

Even more complex conditions arise when the reflected signals are emitted from an obstacle in the aquatic environment. Here we have to reckon with the influence of solid angles inside which the flow of energy of acoustic waves propagates: solid angle, inside which the vibrator sends signals, and solid angle, at which the obstacle area is visible from the center of the wave sensor (see, for example: V. Shuleykin Short course of sea physics. L., Gidrometeoizdat, 1959, p. 400-401). And if the survey in a known manner provides the necessary requirements for navigation, then when surveying in the interests of searching for objects and pipelines under the bottom silt layer or determining the parameters of the boundaries of the continental shelf, requirements for the accuracy of the survey are not provided. Hydroacoustic search in such conditions is accompanied by a large number of false alarms.

When shooting in the continental shelf, to fulfill the accuracy requirements, it is necessary to exclude or reduce the influence of errors that are systematic or slowly changing in nature, which include errors caused by the spatio-temporal variability of the sound velocity field in the survey area; errors caused by the deviation of the instantaneous level from the observed at the level post; errors associated with determining the position and orientation of the instrument coordinate system in the ship coordinate system. When searching for underwater objects and pipelines with a small thickness of silt by a silt pipeline, it is necessary to use only highly directional systems to obtain high resolution. In this case, the system must be low-frequency for good penetration of the signal into the thickness of bottom sediments. The problem of monitoring pipelines and determining the parameters of the boundaries of the continental shelf / arises, as a rule, in shallow water, which requires limited antenna dimensions. Given the relatively small size of silted objects, it is necessary to use a scan of a narrow parametric beam.

In the known method for capturing the bottom topography (patent RU No. 2434246 [4], improving the accuracy of shooting the bottom topography compared to the known method [3] is achieved due to the fact that additionally perform sonar bottom sounding with a parametric sonar with a scanning directional characteristic set at different horizons depths from ship’s hydroacoustic devices with the possibility of moving them both in the vertical and horizontal planes using the sector survey method with scanning the characteristic directionally in the radiation mode of the parametric antenna with the reception of reflected signals by an antenna of the same size as the pump antenna of the parametric antenna, while the width of the directivity characteristic in the reception mode exceeds the size of the viewing sector, and the antenna scanning plane is deflected relative to the position of the vertical location by an angle of 15 degrees in the direction of movement vessel.

However, when solving applied problems, for example, related to the construction of submarine pipelines at great depths, it is very important that all landforms or artificial underwater objects be identified during bathymetric instrumental surveys by measured depths with sound signals generated, in particular, by high-frequency multipath echo sounders for a detailed picture of the bottom topography.

When shooting the bottom topography with multipath echo sounders, the depths in the horizontal plane are measured (formed) with a certain discreteness, which is associated with the angle of the beam direction, the method of beam formation, the frequency of the multipath echo sounder, the resolution of the beam formation. Moreover, this discreteness is generally a function of the depth L = f (H).

For example, for a high-frequency multipath echo sounder of the EM 100 type, used during bathymetric instrumental surveys during design works when laying underwater trunk pipelines for hydrocarbon transportation, the horizontal discreteness of the depth distribution at an equal distance in shallow mode is L = 6.3% N, where N is depth. When the depths are distributed at equal angles, this distance on the lateral rays increases compared to the central rays. This leads to the fact that with an increase in the depth of shooting, it is possible to skip the relief form, which is dangerous for the pipeline. From the point of view of designing the parameters of the pipeline, the intersection of such a dangerous form by the pipeline leads to an increase in the free span of the pipe and an increase in the load at the point of contact of the pipe with a relief of a dangerous shape. When designing the parameters of the pipeline, the basis is the bathymetric profile, and the absence of fixation of the dangerous depth on the profile in real conditions can lead to exceeding the allowable loads on the pipe and, accordingly, to its damage, therefore, the task of determining the probability of missing the dangerous shape of the relief during bathymetric surveying is very important. There are also known methods for shooting the bottom topography (patent RU No. 2272303C1, 10.12.2006 [5], patent RU No. 2292062С2, 01.20.2007 [6], patent RU No. 23232408C1, 06/10/2006 [7], patent EP No. 1426787A1, 09.06. 2004 [8]) also do not solve this problem. The unique geographical location of the Arctic Ocean basin, the insufficient level of hydrographic and geological and geophysical knowledge, the ambiguity in the interpretation of the deep structure of its subsoil, the lack of a clear concept of the formation of this young ocean leads to significant difficulties in determining the external boundaries of the continental shelf for the Arctic states in the legal framework of the UN Convention on 1982 maritime law. The methods for determining the position of the outer boundary of the continental shelf are associated, first of all, with the need to calculate the foot of the continental slope from bathymetric data. In accordance with the provisions of the Scientific and Technical Guidelines of the UN Commission on the Limits of the Continental Shelf, "the foot of the continental slope is defined as the point of maximum change in the slope at its base." Existing algorithms determine the points of local maximums, changes in the slope of the bottom on the continental margin. These points can be a large number in connection with the complication of the relief of the continental margin by lower-order forms. According to the Convention, the maximum change in the slope of the bottom (the second derivative of the relief), corresponding to the foot of the continental slope (PKS), must be at the base of the continental slope (ACS). Therefore, an important task is to determine the position of the ACS, which can objectively be based on bathymetric, geomorphological and geological and geophysical information (International Convention on the Law of the Sea of 1982 - M .: Military Publishing House of the Ministry of Defense of the USSR, 1985, - 224 p .; Scientific -technical management of the Commission on the Limits of the Continental Shelf, New York: Commission on the Limits of the Continental Shelf, 1999, - 92 c). The objective of the proposed technical solution is to expand the functionality while increasing the reliability and informativeness when mapping the relief of the bottom of the water area at the measured depths using hydroacoustic measuring instruments.

The problem is solved due to the fact that in the method of shooting the bottom relief of the water area ([4] prototype), which includes emitting hydroacoustic signals in the direction of the bottom, receiving signals reflected from the bottom surface, measuring distances from the receiving-emitting antenna to the bottom, determining the coordinates of the vessel from external information sources, measurement of side, keel and pitching, the true heading and speed of the vessel, the binding of the measurement results in time, the determination of the true depths with the determination of the correction for the deviation of the action the relative speed of sound in water from the calculated one, mapping the obtained information with determining the geodetic coordinates of the measured depths, in which, when mapping the bottom topography, conjugate topographic and navigation raster maps, additionally perform sonar sounding of the bottom with a sonar and / or surveying echo sounder installed at different depth horizons from ship hydroacoustic means with the ability to move them both in the vertical and horizontal planes using the sectoral method the gap with scanning the directivity characteristics in the radiation mode of the parametric antenna with the reception of reflected signals by an antenna of the same size as the pump antenna of the parametric antenna, while the width of the directivity characteristics in the receiving mode exceeds the size of the viewing sector, and the scanning plane of the antenna is deflected relative to the position of the vertical location by an angle of 15 ° in the direction of movement of the vessel, in which, in contrast to the prototype, simultaneously with the emission of hydroacoustic signals in the direction of the bottom, m magnetic recording by means of a gradiometer towed at a distance of 5 m from the bottom, seismic-acoustic profiling by means of a profilograph with an operating frequency of 3.5 kHz, sea level is measured, while processing the values of the measured depths, linear interpolation of the obtained bottom surface through triangulation is additionally carried out, when mapping the received information with determination the geodetic coordinates of the measured depths assess the degree of spatial uniformity of the coverage with measuring points of the measuring area by determining the external boundaries (contour) of the measurement area, and into a device for recording the bottom relief of the water area, consisting of a receiving-radiating antenna, transmitting unit, receiving-measuring unit, control unit, unit for determining the average speed of sound propagation in water, unit for collecting, processing information and mapping the bottom topography , multi-beam echo sounder, module for visualizing the relief area, sonar Doppler log, satellite navigation system receiver, heading system, pitch meters, we additionally introduced towing a gradiometer, profilograph, and sea level meter connected by their outputs to the inputs of the unit for collecting, processing information, and mapping the bottom topography.

The invention is illustrated by drawings (Fig.1-7).

Figure 1. Structural block diagram of the device. A device for capturing the relief of the bottom of the water area consists of a receiving-emitting antenna 1, a transmitting unit 2, a receiving-measuring unit 3, a control unit 4, a unit for determining the average speed of sound propagation in water 5, a unit for collecting, processing information, and mapping the relief of the bottom 6, a multi-beam echo sounder 7, module visualization of the relief region 8, sonar Doppler lag 9, receiver 10 of the satellite navigation system, heading system 11, pitch meters 12, towed gradiometer 13, profiler 14, sea level meter i'm 15.

The drawings (Fig.2-4) illustrate the application of the algorithm for calculating the contour of the survey area with a multi-beam echo sounder to specific measurements obtained by a multi-beam echo sounder.

Figure 2. Coordinate points of measurements with a multi-beam echo sounder - stereographic projection. Measurement points 16, measurement gaps 17.

Figure 3. Graph of the distribution function of the radii of circles circumscribed around triangles.

Figure 4. The contours of the outer borders and gaps, calculated by the algorithm for shooting (stereographic projection, figure 2). Figa - the overall picture. Figb - enlarged selected area. The contours of the outer borders of the 18 survey, the omissions of the measurements 17, the selected area 19 of the survey, the coordinates 20 of the measured depths.

Figure 5. An example of performing linear interpolation through triangulation.

6. An example of constructing the surface of the second derivatives in the gradient direction, corresponding to the maximum change in the slope of the base at a given point, using the algorithm for constructing the norm surface of the matrix of the second derivative of the depth. Figa - interpolation of the surface by measuring depths. FIG. 6b is the surface of the second derivatives in the direction of the gradient.

7. An example of finding the PKS line (approximation of the PKS line).

The output of the transceiver antenna 1 (Fig. 1) is connected to the input of the receiving-measuring unit 3, the output of the transmitting unit 2 is connected to the receiving-radiating antenna 1, the outputs of the receiving-measuring unit 3 are connected to the input of the unit for collecting, processing information, and mapping the topography of the bottom of the water area 6, the inputs of which are connected to the outputs ship gauges of the components of pitching, heading, speed and coordinates, and the control unit 4 is connected to the transmitting unit 2, the receiving unit 3 and the unit for collecting information, processing and mapping the topography of the bottom 6. The input unit the distribution of the average speed of sound propagation in water 5 in the direction of emission of the hydroacoustic signal through the control unit 4 is connected to the output of the ship's hydroacoustic Doppler lag 9 and the output of the satellite navigation system receiver, and the output is connected to the input of the unit for collecting, processing information and mapping the topography of the bottom 6 of the water area, multipath the echo sounder 7 is connected by its inputs and outputs to the control unit 4 and the input of the unit for collecting, processing information and mapping the topography of the bottom of the water area 6, the visualization module This type of relief 8 is connected at its input to the output of the block for collecting, processing and mapping the relief of the bottom of the water area 6. The towed gradient meter 13, profilograph 14 and sea level meter 15 are connected by their outputs to the inputs of the block for collecting, processing information and mapping the relief of the bottom 6. Device and principle the actions of blocks 1-9 are similar to the devices and the principle of operation of blocks 1-6 of the prototype [4]. At the same time, as in the prototype, the transceiving antenna 1 is assembled from piezoceramic acoustic transducers located in one housing, which are used both for radiation and reception of signals reflected from the bottom. In the radiation cycle, these transducers are connected in parallel, and during the reception of echo signals they work independently of each other.

The transmitting unit 2 consists of a frequency-stabilized crystal oscillator, a shaper of the period of the emitted pulses, a device for generating the duration of the emitted pulse, a synchronizer, a quantization device, a power amplifier, a converter, a switch.

The generator generates continuous oscillations with a frequency of 4.8 MHz, which by means of a synchronizer is reduced to 600 kHz, and a radiation pulse is formed. The power amplifier amplifies the pulse to the value necessary to excite the electro-acoustic transducers of the transceiving antenna 1. Through the switch, the transducers of the transceiving antenna 1 are connected to the transmitting unit 2 during radiation, and to the receiving-measuring unit 3 during reception.

The receiving unit 3 consists of a block of band amplifiers, an antenna amplifier, a main amplifier, a block of control code drivers, a filter block, an amplitude detector, a low-pass filter, a switch, an output amplifier, and is designed to receive, amplify, and frequency select the received signals.

The control unit 4 consists of a micro-command ROM, an address selection control ROM, a microprogram control LSI, two microprocessors, a ROM, a RAM, a hyphenation scheme, three buffer registers and five lines: address lines, micro-lines, lines D, lines M, lines L, and is designed to generate and broadcast teams and information files received from external sources of information, as well as information located in ROM.

The unit for determining the average speed of sound propagation in water 5 consists of a micro command decoder, buffer stages, an address register, an arithmetic logic device, multiplexers, a decoder, line A, line D, and a battery.

The unit for collecting, processing information and mapping the bottom topography 6 consists of receiving registers, a system trunk unit, an amplifier, a memory manager, an operation unit, a command flow control unit, a microprogram control unit, an interrupt unit, and output registers.

The multi-beam echo sounder 7 is a multi-beam echo sounder with a complex linear-frequency modulated signal and is designed to measure depths from 20 to 6000 m. The power of the received signals is scanned in range and angle. The nature of the change in power in the beam with a range depends on the shape of the bottom topography. Of the 32 receiving channels, 256 beams are formed, which makes it possible to obtain a quasi-continuous profile of the relief. The receiving antenna of the multi-beam echo sounder 3 of the frequency range 30 kHz consists of 32 elements.

The towed gradiometer 13 is designed for magnetic imaging and is a proton gradiometer of the type “Sea SPY” or “Marine Magnetic Explorer”. Towed handball gradiometer 13 in deep water towed at a distance of 5 m from the bottom. For stable holding of the towed body at a given distance from the bottom, a DT VARINE 2005EHLWR winch with remote control is used. In shallow areas, the towed handball of the gradiometer 13 is towed to the surface, its location is determined by the length of the cable and the distance to the GPS antenna of the satellite navigation system.

To determine the position of the vessel and information sensors, the equipment of consumers of the GPS satellite navigation system in differential mode (DGPS) operating at two independent control and correction stations, as well as geodetic control and correction stations for working in RTK mode or for receiving Starfix corrections, are used with the necessary accuracy HP via satellite.

Such a coordination system ensures the determination of a place with a mean square error of not more than 0.3 m at any point in the district during round-the-clock operation.

For navigation support, the MS 750 Base type geodetic station, Trimble 5700 RTK and Trimble DSM 2121 shipborne receivers, and a navigation computer with software were also used. Electronic Navigation Information System (ECDIS), ECS -1000 system with dKart Navigator software, ultra-short-range underwater navigation system of the Simrad HRP 4 UR type for high-precision positioning of the gondola of the gradiometer 13 with two transponder beacons.

Profilograph 14 is a bottom profilograph of the “SPB Klein 2275” type (operating frequency 3.5 kHz, resolution 75 cm, maximum towing depth 600 m).

The pitching meters 12 are heading and dynamic displacement sensors of the “Octans” type vessel with compensation of dynamic displacements of 0.01 degrees along the course, vertical displacement, side and keel pitching with a data frequency of 40 Hz.

As a sea level meter used a sea level meter 15 type "GMU-2".

The unit for determining the average speed of sound propagation in water 5 is a sound velocity meter of the type "SVP 15" or type "OLD-1".

The unit for collecting, processing information and mapping the bottom 6 relief is built on the basis of the Trimble Geomatics Office software and mathematics and a geographic information system such as Mapinfo v.7. The operation of the device is as follows.

According to the command pulses generated by the control unit, in the transmitting unit 2, an acoustic pulse is generated and emitted by the receiving-emitting antenna 1 to the bottom side, as well as receiving and converting acoustic signals reflected by the bottom into an electrical signal, transmitting these signals to the input of the receiving-measuring unit 3, in which electrical signals are generated proportional to the time delays in the arrival of signals reflected from the bottom surface, by which the distances from the receiving-emitting antenna are determined nna 1 to signal reflection points on the seabed. At the same time, according to command pulses from control unit 4, electric signals proportional to the Doppler frequency shift of the reference sonar signal from the ship's sonar Doppler speed meter (lag) (the analog of which is the lag described in the book: Absolute and relative lags / Vinogradov K.A., Koshkarev V.I., Osyukhin B.A., Khrebtov A.A. // Shipbuilding, L., 1990, p.30), and electrical signals proportional to the geodetic coordinates x, y from the ship's receiver 10 of the satellite system are input block about definiteness average sound velocity in water 5, which defines the average speed of sound in water according to the algorithms given in [4].

Further, by command pulses from control unit 4, information from blocks 3, 4, and 5 is fed to a block for collecting, processing information, and mapping the topography of bottom 6, which also receives information from ship meters of pitching components 12 and course 11.

In block 6, the correction to the depths measured by the multi-beam echo sounder 7 is determined. Information from the multi-beam echo sounder 7 is fed to the visualization module of the relief region 8.

Information mapping is carried out by applying the geodetic coordinates of the reflection points of hydroacoustic signals from the seabed onto a tablet, which is built by pairing topographic and navigation raster maps in the following sequence:

- the raster of the navigation map in the Mercator projection is subjected to vectorization of the coastline of the navigation map;

- a site is selected that corresponds to the marine area on which the bottom topography is recorded taking into account the vectorization of the coastline of the navigation map;

- a record is made in the final raster of the navigation map;

- the raster of the topographic map in the Gauss-Kruger projection is reduced to the scale of the navigation map;

- the coordinates of the Gauss-Kruger projection are converted into geographical coordinates;

- the conversion of geographical coordinates to the coordinates of the Mercator projection is performed;

- a raster plot is selected that corresponds to the land (coastal) region;

- the topographic map is written to the final raster;

- based on the results of recordings in the final rasters of the navigation and topographic map, the final raster map of the combined navigation and topographic information in the Mercator projection is built;

- on the final raster map displayed on the display device, the path of the vessel is also displayed.

When visualizing the registered bottom topography, the data for the VRML interpreter is generated in the RAM of the computer of the computing device with subsequent loading into the interpreter. For this purpose, a JavaScript node is included in the boot VRML file, whose functions control the area of visible space. Software tools for cartographic visualization are data structures in the SVG format, which supports vector and raster data.

The display in the browser of data in the SVG format is carried out by the interpreter of the declarative language SVG. The data in the SVG structure is generated similarly to the formation of data in the VRML format. Based on the data in the XML structure (geospatial information) received from the database upon request, the browser is converted to the SVG structure using XSLT-T. For the simultaneous presentation of geospatial data in a two-dimensional and three-dimensional representation, support is provided for synchronization of navigation across one and the other scene. A rectangle corresponding to the current region of space is displayed on the cartographic scene, the data of which is loaded into the memory of the VRML interpreter. Synchronization from the side of SVG is based on JavaScript functions built into SVG and HTML. Since synchronization on the part of VRML is more difficult, a JavaScript node is included in the VRML boot file with navigation functions that do not allow a three-dimensional image to go beyond the viewport and constantly monitor the coordinates of the viewport. These coordinates serve as necessary information for synchronization with the cartographic scene, which is possible using the HTML timer.

The navigation system is constructed using an alternative principle to the observation point of a three-dimensional scene, which is alternative to the well-known GA 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. Information from block 6 goes to the visualization module of the relief region 8, by means of which interpolation of heights (depths) is performed using two-dimensional spline functions, and specifically in the form of two-dimensional irregular rational fundamental splines (NURBS) (see, for example: N. N. Golovanov Geometric modeling. M., Fizatlit, 2002. - 472 s), mathematical expressions of which are not given due to the lack of sufficient space. An advantage of the proposed method is the interpolation of elevation points in the form of two-dimensional rational two-dimensional spline-functions NURBS, which allows you to build a smooth surface for any shape of the relief, even for cliffs with a negative angle of inclination. Secondly, the surface of the relief is determined by the analytical dependence, i.e. a finite set of parameters of a fixed set of functions (polynomial splines). The analytical form of the terrain assignment, i.e. in the form of a superposition of analytic functions of two variables, it allows you to use the entire apparatus of differential geometry to describe the morphometric properties of the relief, for example, calculating the value of a function (height, depth) or its differential (slope) at any point (points) of the domain of the function. Third, NURBS provides the ability to locally edit surface shapes. In addition, for the same area of the earth, the DEM data array using NUBRS will be at least an order of magnitude smaller than with the traditional point representation. Consequently, the use of NURBS improves the efficiency of automated geospatial systems by reducing processing time and the required amount of memory. The use of NURBS in computing is a long-held fact - in the graphics packages of all operating systems, NURBS processing and visualization algorithms are integrated, for example, in low-level graphics packages: DirectX and OpenGL for Windows. However, when constructing a DTM, there are obstacles associated with the effect of the occurrence in some situations of a violation of monotony in surface changes — the local appearance of false oscillations. In the inventive method, this obstacle is removed either by adding new points to the array for interpolation, or by using iso-geometric approximation methods with splines. In the first case, the solution to the problem is associated with an increase in the expert’s work in the iterative procedure for constructing NURBS, in the second, with a significant complication of the mathematical algorithms of the technology.

The proposed method implements the technology of building a DEM based on NURBS in the form of an iterative expert automated procedure. The programming language used is the MatLab language. In this system, the quality of DEM construction is determined by expert comparison of the position of contours calculated according to NURBS with the position of the corresponding isohypses (isobaths) on the original map. In a specific implementation of the proposed method, raster maps serve as a source of terrain information.

In the general case, when approximating the profile of the relief with one-dimensional splines, one should specify the values of the first two derivatives at the end points of the section. However, such information is unknown, and it is impossible to obtain it in practice. Therefore, the simplest cubic spline with zero boundary derivatives was used as the base spline for approximating the relief profile along the section. Due to the fact that there are no explicitly defined two-dimensional splines, since it is impossible to construct an infinite system of algebraic equations for matching the first two derivatives in all directions at the adjacent boundaries of two pieces of a spline surface, the construction of a two-dimensional spline function is performed using the tensor product of one-dimensional splines. The coordination of the first two DPC differentials for adjacent rectangular map sections is ensured by overlapping task areas of adjacent NURBS.

Thus, the technology of building DEM in an analytical form based on NURBS allows you to exclude the triangulation stage and thereby eliminate the disadvantages of existing technologies. The proposed implementation of the technology can be adapted to other types of source information, and more complex types of basic splines can be included in it.

When using the proposed method and device for its implementation, designed to capture the bottom topography of the water area, the accuracy requirement for determining the depth when shooting the topography of the bottom of the water area is established by the current regulatory documents, due to the possibility of measuring the Doppler frequency shift of the reference sonar signal of the sonar doppler log, absolute speed movement of a vessel with an echo sounder through external sources of information (for example, satellite navigation systems type GPS), which determines the average vertical velocity of sound propagation in aqueous medium. When shooting the bottom topography with an echo sounder, the mean square error in determining the vertical velocity of sound propagation should not exceed ± 7.5 m / s. The fulfillment of this requirement can be ensured if the speed of the vessel is determined with a mean square error not exceeding ± 0.037 m / s, which can be done provided that geodetic coordinates are determined with a mean square error not exceeding ± 7.8 m.

The navigation systems installed on hydrographic vessels, in particular the combined receiver-indicators of satellite and coast-based satellite navigation and radio navigation systems, make it possible to determine geodetic coordinates with an accuracy of ± 6.0 m, and when operating in differential mode with an accuracy of ± 3.0 m.

When pairing topographic and navigation raster maps when mapping the topography of the bottom, the errors of the resulting raster map are no more than two pixels. For example, for a map scale of 1: 250000 with a resolution of 400 dpi, this is 30 m on the surface of the earth, which does not exceed the errors of the raster map itself.

In the process of shooting, informative depths are selected from the set of measured depths, which are corrected by corrections for the speed of sound and are tied to the calculated probable coordinates for drawing on a working tablet and for an operational assessment of the quality of shooting.

Next, an assessment is made of the degree of spatial homogeneity of the coverage with measuring points of the measuring area, namely, the exact external boundaries (contour) of the measuring area, the presence of gaps, local gaps (holes) and their boundaries in accordance with the algorithm for calculating the contour of the survey area with a multipath echo sounder 7.

The results of surveys with a multi-beam echo sounder are large arrays (files) of data, including the values of latitude, longitude and depth when passing a survey tack. According to the presented measurement results, the problem arises of assessing the degree of spatial uniformity of coverage by measuring points of the measuring area, namely, the exact external boundaries (contour) of the measuring area, the presence of gaps, local gaps (holes) and their boundaries. In turn, the determination of these boundaries with a multipath echo sounder 7 will allow you to accurately determine the area of the survey.

Given the large volume of measurements obtained using the multi-beam echo sounder 7, the solution to the problem of determining the boundaries of the measurement should be sought using computer-aided computing automation. To build an automated algorithm for calculating the boundaries of measurements, it is necessary to formalize the idea of a gap between the points of depth measurement. The construction of an automated algorithm is based on the theory of computational topology (see, for example: Zomorodian A. Topology for Computing. - ser. Cambr. Mon. Appl. Coll. Math. Cambr. Univ. Press, 2005, 259 p.).

The core of the algorithm is as follows. For simplicity, we assume that the coordinates of the measurement points are given on the Euclidean plane with a natural metric (the distance between the points). Essentially, the set of coordinates of the points {x _i , y _i } (i = [1, N]) of the depth measurement by the multi-beam echo sounder 7 is an unordered "cloud" of points. To organize the set of coordinates of points, it is necessary to specify some sorting formal structure. We choose a triangulation network as such a structure. Then this network defines an array of sets of three points {i ₁ , i ₂ , i ₃ } forming a triangle in this triangulation. As a matter of fact, the array {i ₁ , i ₂ , i ₃ } defines the ordering structure on {x _i , y _i }.

The technology of measurement with a multi-beam echo sounder 7 involves obtaining measuring points "uniformly" distributed in space, that is, with almost the same distances between adjacent points. We denote this distance by R. From this point of view, the structure defined by the set {i ₁ , i ₂ , i ₃ } is redundant. Indeed, by construction, the set {i ₁ , i ₂ , i ₃ } includes triangles whose side lengths are arbitrary, that is, they are determined only by the general triangulation process. Consequently, the set {i ₁ , i ₂ , i ₃ } includes both triangles with short side lengths formed by close interior points, and triangles with long side lengths formed by boundary triangles whose sides form a convex hull {x _i , y _i } . (The convex hull {x _i , y _i } is the smallest convex set of points on the plane containing {x _i , y _i }).

We exclude from the set {i ₁ , i ₂ , i ₃ } triangles for which the length of either side exceeds the value of R. As a result, we obtain the set {i ₁ , i ₂ , i ₃ } _{≤R of} triangles for which all sides are less than or are equal to R. Then the union of the set of triangles {i ₁ , i ₂ , i ₃ } _≤R will determine the exact area covered by the survey with a multipath echo sounder.

By the construction of triangulation in the set {i ₁ , i ₂ , i ₃ }, each edge {i ₁ , i ₂ } of the triangulation is part of the sides of either two triangles or one. Obviously, only those sides of the triangles of the set {i ₁ , i ₂ , i ₃ } _≤R that are represented in {i ₁ , i ₂ , i ₃ } _≤R in a single copy make up the boundary of this region. The triangles corresponding to these sides are boundary. At the same time, if some side of the triangle is represented in {i ₁ , i ₂ , i ₃ } _{≤R by} more than one instance, then it lies inside the region (with the possible exception of the end (s) point). We denote the set of boundary sides of triangles by the symbol {i ₁ i ₂ ,} _≤R;

The whole algorithm for calculating the contour of the survey area with a multipath echo sounder 7 is a simple linear sequence of calculations.

Input: an array of latitudes and longitudes of the measurement points with a multipath echo sounder - {φ _i , λ _i }.

Step 1. For {φ _i , λ _i } calculate the arithmetic mean longitude and latitude - [φ ₀ , λ ₀ ].

Step 2. Convert the geographical coordinates {φ _i , λ _i } to stereographic coordinates {x _i , y _i }. The stereographic projection pole sets the values [φ ₀ , λ ₀ ].

Step 3. Triangulate {x _i , y _i } using the Delaunay method. The result is {i ₁ , i ₂ , i ₃ }.

Step 4. Calculate the lengths of the sides of the triangles {i ₁ , i ₂ , i ₃ }. The result is the set {l (i ₁ i ₂ )}.

Step 5. The value of R is calculated: find the distribution function {l (i ₁ i ₂ )}, the value of R is equal to the length at which saturation of the distribution function {l (i ₁ i ₂ )} is achieved (see Fig. 3).

Step 6. Find the set, {i ₁ , i ₂ , i ₃ } _≤R .

Step 7. Find the set {i ₁ i ₂ } _{≤R; G.}

Step 8. Using {i ₁ , i ₂ , i ₃ } _≤R and {i ₁ i ₂ } _{≤R; Γ} , define a connected sequence of boundary sides - the set {P _j } (j = [1, K]. In total K polygons. Each connected sequence forms a simple polygon. Each polygon defines either an external boundary or an internal boundary (hole boundary).

Step 9. Using {x ₁ , y ₁ } and {P _j }, determine the set of coordinates of the corner points of the boundaries of the polygons - {XY _j }.

Step 10. Using {XY _j }, define the set {XY _n } _OL (n = [1, N], N≤K) of sets of corner points of the polygons that form the outer boundaries. Criterion: polygons from the set do not intersect in pairs [XY _n } OL (with the possible exception of one point touching the boundary of another polygon).

Step 11. Excluding the set {XY _n } _OL from {XY _j }, we obtain {XY _m } _H (m = [1, M], M = NK) - the set of sets of corner points of the polygons that make up the internal boundaries (hole boundaries). If {XY _m } _{H is} not empty, then for each polygon from {XY _n } _OL find the indices Inch of those polygons from {XY _m } _H that lie completely in it.

Step 12. The stereographic coordinates {XY _m } _OL and {XY _m } _{H are} converted to the geographic coordinates {φλ _n } _OL and {φλ _m } _H , given that according to step 2, the values of [φ ₀ , λ were the pole of the stereographic projection ₀ ].

Output: Geographic coordinates of the angular external {φλ _n } _OL and internal {φλ _m } _H polygons, the set of indices of nesting of internal polygons in external polygons.

The conversion of geographic coordinates to stereographic is due to the need to move from a spherical to a Euclidean metric.

The use of the Delaunay method is determined by the extreme properties of the triangulation obtained by this method (see, for example: D'Azevedo E.F., Simpson R.V. On optimal interpolation triangle incidences. // SIAM J. Sci. Statist. Comput., 1989. 10 (6). P. 1063-1075). In particular, for the Delaunay triangulation, a characteristic property is that only the points forming this triangle fall inside the circle circumscribed around each triangle. Delaunay triangulation triangles are “stable” in the sense that they are most similar to regular ones and their sizes tend to be the same.

As R, one can use not only the trivial Euclidean metric - the length of the edge of the triangle, but also other metrics isomorphic to it, for example, the radius of the circle circumscribed around the triangle. The latter is due to the fact that Delaunay triangulation minimizes the maximum radius of the circumscribed circle among all triangulation triangles.

The output of the algorithm allows us to calculate the total area covered by hydrographic survey with a multi-beam echo sounder 7. However, if in those cases where the coordinates of the boundary contours are not important, but you only need to estimate the survey area, then the algorithm can be completed in step 6. Then, using {φ _i , λ _i }, calculate the area of each spherical triangle from {i ₁ , i ₂ , i ₃ } _≤R and add, obtaining the desired total shooting area.

The figures (Fig.2-4) show illustrations of the application of the algorithm to specific measurements obtained by the multi-beam echo sounder 7.

The determination of these measurement boundaries with a multipath echo sounder 7 will allow you to accurately determine the area of the survey.

To determine the foot of the continental slope (PKS), algorithms based on a three-dimensional determination of the foot of the continental slope, i.e. determination of PCD is carried out over the entire distribution area of the measured depths, while in the known methods, the algorithms are developed on the basis of a two-dimensional determination of PCD, i.e. determination of PKS is carried out according to the depth profile. These algorithms are developed in the Math Lab application package.

The input data of the algorithms is a bathymetric data base compiled on the basis of depth measuring plates. A tablet is an array of two-dimensional coordinates of points and depths at these points. The depth measurement error is 1% of the absolute value. Many measurement points distributed unevenly form a polygon with a non-convex boundary and vertices at the “boundary” points.

In view of the introduced randomization, the output of the algorithms yields a band defined by two bounding extreme broken lines. Broken lines are defined as a sequence of line segments on a tablet. The most extreme of these lines form a strip, inside which lies the real line of the PKS. The width of this strip in different parts of the tablet changes, reflecting the stability of data in a particular region of the map. Based on this, you can specify specific regions in which the in-depth information requires more clarification.

In order to avoid the error arising from the interpolation of the surface due to the non-uniform distribution of measurements, the tablet was limited by a non-convex polygon to search for the PCB line inside it. The algorithm is based on the construction of the convex hull of points ({x _i }, {y _i }) using the Graham scan method. The algorithm uses the LIFO structure (Last In - First Out), “Last Entered, First Entered”) - the S stack, in which points ({x _i }, {y _i }) are stored - candidates for the “boundary points” of the convex hull ( at the end of the algorithm, the stack will contain points that form a convex hull in the traversal order). Two auxiliary procedures are also used - Top (S) and Next_To_Top (S), which return the highest and the next (second from the top) after the highest point in the stack, respectively. Push (x _i , y _i ), S and Pop (S) are the standard operations of adding a point to the stack (at the top of the stack) and extracting (deleting) the highest point.

The pseudocode of Graham's algorithm is as follows.

Let (x ₀ , y ₀ ) be a point from the set of dimensions with a minimum coordinate y or the leftmost of such points if there are matches.

Let [(x _i , yi, ..., (x _n , y _n )] be the remaining points of this set sorted in ascending order of the polar angle, measured counterclockwise relative to the point (x ₀ , y ₀ ) (if the polar angles of several points coincide, then all these points are deleted from the set except for the one farthest from the point (x ₀ , y ₀ )):

Push (x ₀ , y ₀ ),

S Push (x ₁ , y ₁ ),

S Push (x ₂ , y ₂ ), S

For i ← 3 to N do while (the angle formed by the points Top (S) and Next_To_Top (S) and (x _i , y _i ) forms a non-left turn) do

Pop (s)

Push (x _i , y _i ), S

Return S.

Further, to reduce the empty space at the border of the tablet, the resulting polygon is refined by replacing the long edges with shorter ones. As a result, we obtain a non-convex polygon bounding the measurement region.

When processing the results of the experimental data, linear interpolation through triangulations was chosen, since it provided the best stability when measuring the PCD line under the action of a test disturbance (Fig. 5).

Based on the obtained surface interpolation algorithm, the surface of the second derivatives in the gradient direction is constructed corresponding to the maximum change in the slope of the base at a given point (Fig. 6) using the algorithm for constructing the norm surface of the matrix of the second derivative of depth.

Based on the surface model of the second derivatives, the PCB line is calculated. For each tablet, a gradient barrier value is calculated based on the dispersion of the gradient throughout the tablet. The algorithm starts from a point lying inside the border of the tablet at a certain distance from it. After determining the highest point in the field of second derivatives for the current profile, the algorithm proceeds to the next profile and finds the highest point for it in a displaced neighborhood of the previous one. The selected points, the height of which turned out to be greater than the indicated barrier, form a sequence of ends of the segments of the polygonal line that defines the approximation of the PCB line (Fig. 7).

Distinctive features:

- use as source data an array of two-dimensional coordinates of points and depths at these points;

- the possibility of determining confidence, within which with a probability of 95% lies the foot of the continental shelf.

The results obtained, which fully comply with the requirements of the UN Commission and the Scientific and Technical Guide for the Limits of the Continental Shelf, provide additional information for the expert assessment of the ACL, and, therefore, can be used to determine and justify the external border of the continental shelf of the Russian Federation in the Arctic Ocean.

To confidently detect potentially dangerous objects, a corridor 60 m wide along the axial line of the route is worked out with a distance between profiles of 10 m. Then, up to a width of the corridor of 400 and 2000 m (expansion areas), the step between profiles is 50 m. This allows you to confidently track linearly elongated objects - pipes, cables, etc. For control, perform measurements on longitudinal tacks after 1 km.

Shooting of the bottom topography is carried out by multipath echo sounders without gaps with overlapping adjacent bands. To capture the bottom topography, multi-beam echo sounders (Sea Beam 1180, Simrad EM 3002) are used. Sonar imaging is performed using a 500 kHz sonar. The composition of the areal survey complex includes sound velocity meters and vertical pitch and roll trim sensors, which provide proofreading of the data of the area bathymetric and sonar surveys.

The measured depths in post-processing are corrected by depths at sea level according to the data obtained from the sea level meter 15. Based on the results of the survey, depth tablets are compiled on a scale of 1: 2000.

The practical implementation of the proposed method of technical complexity does not represent in view of the fact that its implementation uses standard measuring instruments installed on hydrographic vessels designed to record the bottom topography.

Information sources

1. Kolomiychuk N.D. Hydrography. L., GUNiO of the Ministry of Defense of the USSR, 1988, p. 240-277.

2. Hare R. Depth and position error budgets for multibeam echosounding // International Hydrographic Review. 1995, v. LXXII, No. 2, p. 37-69.

3. Patent RU No. 2340916.

4. Patent RU No. 2434246.

5. Patent RU No. 2272303C1, 12/10/2006.

6. Patent RU No. 2292062C2, 01.20.2007.

7. Patent RU No. 23232408C1, 06/10/2006.

8. EP patent No. 1426787A1, 09.06.2004.

Claims (2)

1. The method of shooting the bottom topography of the water area, including emitting hydroacoustic signals in the direction of the bottom, receiving signals reflected from the bottom surface, measuring distances from the receiving-emitting antenna to the bottom, determining the coordinates of the vessel from external sources of information, measuring the side, keel and vertical pitch, true heading and vessel speed, reference of measurement results over time, determination of true depth values with determination of correction for deviation of the actual speed of sound in water from the calculated one, mapping the information obtained with the determination of the geodetic coordinates of the measured depths, when mapping the bottom topography, conjugate topographic and navigation raster maps, additionally perform sonar sounding of the bottom with a sonar and / or surveying echo sounder installed at different depth horizons from ship’s sonar equipment with the possibility of moving them in vertical, and in horizontal planes by sector survey method with scanning directivity characteristics in the radiation mode a parametric antenna with receiving reflected signals by an antenna of the same size as the pump antenna of the parametric antenna, while the width of the directivity characteristic in the receiving mode exceeds the size of the viewing sector, and the antenna scanning plane is deflected relative to the position of the vertical location by an angle of 15 ° to the side of the vessel, different in that, simultaneously with the emission of hydroacoustic signals in the direction of the bottom, magnetic recording is performed by means of a gradiometer towed at a distance of 5 m from the bottom seismoacoustic profiling by means of a profilograph with an operating frequency of 3.5 kHz, sea level is measured, when processing the values of the measured depths, linear interpolation of the obtained bottom surface through triangulations is additionally performed, when mapping the received information with the determination of the geodetic coordinates of the measured depths, the degree of spatial uniformity of the coating by measuring points is evaluated measuring area by determining the external boundaries (contour) of the measuring area. 2. A device for capturing the relief of the bottom of the water area, consisting of a receiving-radiating antenna, a transmitting unit, a receiving-measuring unit, a control unit, a unit for determining the average speed of sound propagation in water, a unit for collecting, processing information and mapping the bottom topography, a multi-beam echo sounder, a module for visualizing the relief area, sonar Doppler log, satellite navigation system receiver, heading system, pitch meter, characterized in that the device for recording the bottom topography is additionally introduced towed gradiometer, profilograph and sea level meter, connected by their outputs to the inputs of the unit for collecting, processing information and mapping the bottom topography.

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