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    • 专利摘要:
    A method of observing a region of the earth's surface, said region of interest (RI), implementing a plurality of satellites (SAT1, SAT2) spaced along at least one moving orbit (O), said method comprising: acquiring by at least two of said satellites, during a same passage over said region of interest and during successive acquisition periods, a plurality of images of the earth's surface, said partial images, each covering a portion (RO1, RO2) of said region of interest; and obtaining an image covering the whole of said region of interest by merging at least two said partial images, having a predefined time offset between their acquisition periods, for each of said at least two satellites. Satellite system for observing a region of the earth's surface for the implementation of such a method, and ground segment (ST) belonging to such a system.
    公开号:FR3023435A1
    申请号:FR1401509
    申请日:2014-07-04
    公开日:2016-01-08
    发明作者:Herve Sainct；Vincent Soulignac
    申请人:Thales SA；
    IPC主号:
    专利说明:

    [0001] METHOD FOR OBSERVING A REGION OF THE GROUND SURFACE, PARTICULARLY LOCATED WITH HIGH LATITUDES; The invention relates to a method for observing a region of the earth's surface by means of a plurality of satellites sharing the same orbit, as well as on a ground segment. and on a satellite system for implementing such a method. The invention is particularly applicable to the observation of regions of the Earth's surface located at high latitude (greater than or equal to 60 ° North or South) by means of satellites located in high elliptical orbits (HEO, for "Higly Elliptical Orbit ") and inclined. These orbits are characterized by a low altitude perigee (typically of the order of 500-1000 km), a high altitude apogee (typically greater than 35.786 km, the altitude of the geostationary satellites) and a high inclination (typically greater than 50 ° and most often between 50 ° and 90 °). The invention is however not limited to the case of inclined HEO orbits; it can also be applied to the case of observation satellites moving on orbits of other types, for example Tundra orbits. Most of the satellite observation services are operated either from geostationary platforms or from low-scrolling orbits. The former guarantee a very wide coverage (about one-third of the globe) and a permanence of observation (fast rate of shooting, allowing for example to measure the movements of clouds), 25 while the seconds allow better spatial resolutions at the same time. detriment of permanence (scrolling orbits with a periodicity of the hour type not allowing, for example, to measure rapid atmospheric evolutions). Geostationary orbits have heretofore been favored for applications such as the re-fitting of weather forecast models, and have given rise to the development of dedicated satellite series such as "Meteosat" and "Goes", whose images regularly Repetitions allow many estimates, including the calculation of wind speeds (AMV, "Atmospheric Motion Vectors"), the first and essential product of climate prediction. There are, however, terrestrial areas at high latitudes where the positioning of a satellite in geostationary orbit - necessarily located above the equator - does not allow to obtain correct images, because of the angle of important inclination under which these regions are observed. For this reason many Nordic countries are poorly served by currently deployed geostationary satellite systems, and are considering particular projects in more suitable orbits. These will typically be highly inclined HEO-type orbits, whose apogee, much higher than the perigee, is in the same hemisphere as the country to be served. The inclination of the orbit makes it possible to observe the regions situated at high latitudes at a relatively low angle of inclination; the high altitude of the apogee, relative to that of the perigee, ensures that the satellite spends most of its orbital period over the region of interest (for example 8 hours exploitable for observation in a period orbit 12h). For example, the TAP orbits ("Three-APogee", that is, orbit at three apogees per day) and Molnyia. Figure 1 compares a HEO orbit with low orbits (LEO, for "Low Earth Orbit"), medium (MEO, for "Medium Earth Orbit") and geostationary (GEO). Since these orbits are not geostationary, permanent observation from a single satellite is impossible, which leads to the deployment of two or more satellites in similar or different inclined orbits, shifted so that when one of the satellites loses the visibility of the region of interest (typically by returning to its perigee) another is present to take the relay. One consequence of the use of HEO orbits is that, unlike geostationary observation systems, in which an image of the region of interest is taken entirely by the same satellite, the systems adapted for high latitudes conventionally envisage to regularly share the coverage of the region of interest between two satellites, with a part of said region of interest covered by a first "partial image" acquired by one of the satellites, while the other part of said region of interest interest is covered by a second "partial image" acquired almost simultaneously by the next satellite. In such a case, a correct overlap between the two image parts is necessary, which creates a constraint on the location of the satellites and their orbit. Many such systems have been envisioned, such as the Canadian PCW system which considers inter alia pairs of satellites in TAP orbits, to obtain regular images of the entire region of interest. These orbits are well adapted, geometrically, to the observation missions. However, they have certain important drawbacks: First, the setting of a satellite on an HEO orbit has a significant energy cost and the greater the greater the inclination and / or the altitude of the perigee. This limits the mass of satellites that can be loaded onto a launcher and / or increases the cost of launching. Secondly, the low altitude of the perigee - required to increase the time spent at the apogee, useful for observation causes the regular circulation of the satellite in or near the Van Allen belts, where the radiation environment is extremely aggressive: this severely limits the life of the on-board electronics, and / or imposes heavy shielding which subsequently increases the cost of launching the satellite. It would therefore be desirable to use less inclined and / or less elliptical orbits, but this would unacceptably degrade the observation (too oblique observation and / or coverage gaps of the region of interest at the junction between the partial images). The invention aims to overcome the aforementioned drawbacks of the prior art. More specifically, it aims to relax the constraints on the HEO orbits of satellites used for observing regions of the Earth's surface located at high latitudes, without giving up a complete and continuous observation. For example, to appreciate the importance of a reduction of inclination of the HEO orbits, we can consider an orbit with a perigee at 200 km and an apogee at 42,000 km. For such an orbit, the launchers' manuals make it possible to verify that a reduction of inclination from 64.9 ° to 51.8 °, all other equal parameters, would allow a quasi-doubling of the launable mass.
    [0002] The object of the invention is achieved by exploiting an increase in the frame rate of images - made possible by the technological progress of embedded imaging devices - to allow a relaxation of the constraint due to the overlap between partial images and thus to allow use of less expensive orbits in terms of inclination and / or less penalizing in terms of radiative doses. An object of the invention making it possible to achieve this goal is a method of observing a region of the terrestrial surface, called the region of interest, using a plurality of satellites moving along at least one orbit. said method comprising: - acquisition by at least two of said satellites, during the same passage over said region of interest and during successive acquisition periods, a plurality of images of the terrestrial surface, said partial images, each covering a portion of said region of interest; and obtaining an image covering the whole of said region of interest by merging at least two said partial images, having a predefined time offset between their acquisition periods, for each of said at least two satellites. According to various embodiments of such a method: Partial images, said of the same rank, can be acquired at the same time by said satellites; the number of said satellites, said or each said moving orbit and said acquisition periods being chosen so that partial images of the same rank, taken in combination, provide a partial coverage of said region of interest, having gaps of blanket. Said partial images can be obtained by scanning and, when acquiring a first set of partial images of the same rank, said scanning starting close to said coverage gaps, whereas, at the subsequent acquisition of a second set of partial images of the same rank, said scan terminating near said coverage gaps - Each said partial image can be obtained by scanning a respective observation region, determined so that it does not overflow of said region of interest. The method can implement exactly two satellites. - Which said satellites can be spaced along the same scrolling orbit. Said image covering the whole of said region of interest can be obtained by merging exactly two said partial images for each of said satellites, acquired during successive acquisition periods. Said region of interest may have a spherical cap shape. Said or each said moving orbit may be an inclined high elliptical orbit of the HEO type and said region of interest may be constituted by a portion of terrestrial surface having a latitude greater than or equal to a limit value L, with I_50 ° and preferably 160 °. The method may also comprise an operation of allocating, at each pixel of each said partial image, a set of information representing a moment of acquisition and a point of the terrestrial surface corresponding to said pixel, said set of information being used when merging said partial images.
    [0003] Another object of the invention is a ground segment comprising: at least one satellite receiver configured to receive, from at least two satellites spaced along the same moving orbit, signals representative of images of the earth's surface, partial images, each covering a portion of the same region of interest and acquired during successive acquisition periods during the same passage of said satellites above said region of interest; and a data processor configured to merge at least two said partial images for each of said at least two satellites, said partial images received from each said satellites having a predefined time offset between their acquisition periods, in order to obtain a image covering the whole of said region of interest. Yet another object of the invention is a satellite system for observing a region of the earth's surface, called a region of interest, comprising: a space segment comprising a plurality of satellites moving along at least a scrolling orbit, configured to acquire, during the same passage over said region of interest and during successive acquisition periods, a plurality of images of the earth's surface, said 20 partial images, each covering a portion of said region of interest, and for transmitting said partial images to a ground segment; and a ground segment as mentioned above. According to an advantageous embodiment of such a system, said or each said moving orbit may be a high elliptical orbit - of the HEO type - and said region of interest may be constituted by all the points of the terrestrial surface having a latitude greater than or equal to a limit value L50 ° and preferably L60 °. Other features, details and advantages of the invention will be apparent from the description given with reference to the accompanying drawings given by way of example in which: FIG. 1 illustrates LEO, MEO, GEO and HEO orbits; FIG. 2 represents, in a simplified manner, a satellite system for observing a region of the terrestrial surface by means of a plurality of satellites on an HEO orbit suitable for the implementation of the invention; FIG. 3 illustrates a partial coverage, with gaps, of a region of interest at high latitudes obtained by merging two partial images acquired by two satellites offset along the same orbit HEO; FIG. 4 illustrates the coverage obtained, conventionally, by two satellites offset along the same polar HEO orbit; FIGS. 5a to 5c illustrate a first embodiment of the invention; and FIGS. 6a to 6d illustrate a second embodiment of the invention. FIG. 2 very schematically illustrates a satellite system for observing a region of the terrestrial surface suitable for implementing the invention. Conventionally, the system comprises a space segment and a ground segment. The space segment comprises at least two SAT1, SAT2 observation satellites traveling along the same HEO-type orbit O. Since the orbit is elliptical, the speed of the satellites varies greatly between apogee (minimum speed) and perigee (maximum speed); therefore their spacing is also variable in time. In the case where the number of satellites is equal to two, their spacing corresponds to an orbital half-period, so that when the satellite SAT1 is near the apogee, the other satellite SAT2 is near the perigee and vice versa . The satellites each carry a generally scanning instrument (not shown) for acquiring an image of a portion of the earth's surface. The "area of observation" refers to the portion of the Earth's surface observed by each said satellite at a given moment (as the O orbit is moving, the viewing regions move with the satellites). In the figure, the references RO1 and RO2 indicate the observation regions of the two satellites SAT1 and SAT2. Satellites are also equipped with a transmitter enabling them to transmit signals representative of the acquired images towards earth T. The ground segment comprises at least one terrestrial station or ground station ST equipped with a satellite receiver RS for receiving the signals transmitted by the satellites SAT1, SAT2, as well as a data processor PD (computer or set of computers) making it possible to process these signals to reconstruct images of a region of interest on the Earth's surface. Alternatively, the satellite receiver (s) and the data processor may not be co-located. The system may comprise more than two satellites - for example three - and more than one ground station (it is customary to use two or more satellites to increase the acquisition time of each satellite). The satellites constituting the space segment of the system are generally identical, but this is not essential. In addition, they do not necessarily share the same orbit: more generally, it can be considered that each satellite moves in a proper HEO orbit, these orbits (or some of them) possibly coinciding. It should be noted that Figure 2 is not to scale. In particular, it greatly underestimates the altitude of the O orbit and the distance between the satellites. As will be explained in more detail below, a satellite observation system according to the invention differs from a system according to the prior art (for example of the aforementioned PCW type) essentially by: - the choice of the O orbit, which may be less inclined and / or less elliptical; the configuration of the acquisition instruments carried by the satellites (rate of acquisition of the images, scanning, etc.); and the processing of the data implemented by the data processor PD.
    [0004] Figure 3 shows the Earth T seen by its north pole PN, with a region of interest RI shaped spherical cap including all points of latitude greater than or equal to 60 ° N. The figure highlights the observation regions at a given instant of the two satellites SAT1, SAT2 constituting the space segment of an observation system according to the invention: RO1 and R02. It should be noted that when the SAT1 satellite is near the apogee, its observation area covers the entire area of interest, while the SAT2 satellite is located near the perigee and flies over the southern hemisphere. Then there is an intermediate period, in which SAT1 moves away from the climax while SAT2 approaches it; during this period, the two satellites each have a partial visibility of the region of interest. Finally, we arrive at a configuration in which the region of interest is observed only by the satellite SAT2. The figure relates to the intermediate period, and more precisely to a moment when the two observation regions RO1 (satellite SAT1) and RO2 (SAT2) cover roughly equivalent portions of the region of interest RI, the region RO1 being shrinking progressively in favor of R02. It is noted that the observation regions "overflow" from the region of interest RI and overlap partially, but especially because, due to an orbit O insufficiently adapted (inclination too low and / or climax too low), they leave there are two gaps in coverage, identified by reference LC; these gaps move in time, and disappear when the region of interest is fully observed by a single satellite. The specification of an observation system of the type of Figure 2 normally requires that images covering the entire region of interest are provided at regular intervals, for example every 30 minutes. The presence of LC coverage gaps prevents this goal from being achieved, and is therefore unacceptable. According to the prior art, it is possible to "close" the gaps by increasing the inclination of the O orbit of satellites SAT1, SAT2 and / or the altitude of its apogee, or even by providing an additional satellite but, as explained above, these solutions are expensive to implement.
    [0005] The invention proposes, on the contrary, to relax the constraints on the orbit O, and to "close" the coverage gaps that result by increasing the acquisition rate of the images, which is made possible by the progress of the instruments imaging, and by exploiting the rotation of the Earth between two acquisitions of successive or close images. According to the invention, the satellites SAT1 and SAT2 are used to acquire a first pair of partial images, corresponding to the observation regions R01, R02, during a first acquisition period of equal duration, for example at 10 min (partial "first row" images). Then, these same satellites are used to acquire a second pair of partial images ("second rank") during a second acquisition period of approximately the same duration. Between the two acquisition periods, the earth turned around its axis and the two satellites advanced along their orbit; as a result, coverage gaps have shifted relative to the land surface. Four partial images are available which, taken in combination, cover the entire region of interest and whose measurements are contemporaneous to within 20 minutes, even though the total recovery of the region of interest is not possible. from a single pair of partial images acquired from orbit O. In some cases, the coverage can be provided by three, instead of four, partial images. Thus, when a first satellite moves away from the apogee while a second satellite appears on the horizon of the region of interest, an image acquired solely by the first satellite is combined with two partial images acquired just afterwards. the two satellites. Later, two partial images are combined with an image acquired only by the second satellite after the first one has disappeared on the horizon. It will also be appreciated that when one of the satellites is near the apogee, it can acquire a single image of the region of interest without the need to combine partial images.
    [0006] It should be noted that, even in the case of a "classical" acquisition, the pixelation of the pixels is not the same throughout the image, because the partial images are acquired by scanning, which takes time. Moreover, in a product of type L1C one does not ask that all the pixels be simultaneous, but only that each one of them is dated and associated with a point of the terrestrial surface. Concretely, for the implementation of the invention it will be possible to proceed as follows: First of all it is necessary to determine the maximum admissible time interval between two complete images, and to verify that this interval allows the acquisition of two partial images. The timing of the two pairs (or more) of partial image acquisitions is thus determined. Then, progressively release the constraints of the orbit O, reducing its inclination and / or lowering its apogee, by checking by simulation that the combination of two pairs (or more) of acquisitions still allows the reconstruction of complete images of the region of interest at the required rate. For example, two satellites spaced half a period apart in a polar orbit (90 ° inclined to the equatorial plane) with a perigee of 20 to 29,500 km and a peak at 54,800 km cover the entire region of the Earth's land surface. greater than or equal to 60 ° N with a rate of one image every 10 minutes. This can be verified in FIG. 4, where RO1 is the region observed by satellite SAT1 six hours after its apogee and RO2 is the region observed by satellite SAT2 at the same time, ie six hours after its passage to perigee (for the sake of brevity, we will call this moment "apogee + 6h"). The figure also makes it possible to verify that the ring between latitude 50 ° N and 60 ° N is not correctly observed because of two LC coverage gaps. If the inclination is reduced to 85 °, leaving all other 30 parameters unchanged, the coverage gaps extend within the region beyond 60 ° N of latitude, which is not acceptable. . This can be observed in FIG. 5a, corresponding to the instant "apogee + 6h", as in FIG. 5b, corresponding to the instant "apogee + 6.333h", that is to say 20 minutes later. However, if we combine the two images (Figure 5c), we obtain again complete coverage beyond 60 ° N. Conversely, the combination of images acquired at different times makes it possible to extend the coverage at lower latitudes for a given inclination of the satellite orbit. FIGS. 6a, 6b (substantially identical to FIG. 4) and 6c correspond, respectively, to an orbital inclination of 90 ° and to the instants "apogee + 5,83333h", "apogee + 6h" and "apogee + 5", 3333h "; Figure 6d is a combination of these images, taken over a time interval of 30 minutes, which is still acceptable. It can be verified that the composite image allows full coverage up to a latitude of 55 ° (dashed circle). This example is interesting because it shows a case where one must combine more than two pairs of elementary images or "sub-images" (three, in this case). FIGS. 4 to 5c make it possible to verify that, after the acquisition of two pairs of sub-images: most points of the region of interest are covered by two pixels, since seen twice by the same satellite or once by each satellite; Some of these points are covered by three or four pixels, since seen simultaneously by the two satellites during an acquisition, or both; - And some others by a single pixel, because located in correspondence of a gap coverage for the first or second acquisition, this gap being filled by the other acquisition. In a conventional strategy, taking a single satellite partial image, these points would not have been covered. After the double acquisition, it is necessary to merge the four partial images to arrive at a final image where each point is covered by a single pixel. For those points of the area of interest that are covered by two or more images, any conventional strategy of reconstituting the final pixel from the set of original pixels by combination, extrapolation, resampling, etc. is achievable. In accordance with the invention, the terrestrial rotation that took place between the first and the last acquisition displaced the coverage gaps; consequently, the points of the region of interest which were initially in correspondence of one of these gaps are now covered by one (and only one) pixel acquired during the second acquisition, and conversely the points corresponding to a gap in coverage during the second acquisition are covered by a pixel obtained via the first acquisition. For these points, it is sufficient to retain the only pixel that corresponds to them, in all the available acquisitions (before, if necessary, perform a resampling of the image, which is conventional). These remarks can be generalized to cases where more than two pairs of sub-images are combined, as for example in the embodiment of FIGS. 6a-6d.
    [0007] In a particularly simple embodiment of the invention, two satellites with identical imagers are used, which acquire partial images in the same way. In this embodiment, each satellite acquires - generally by scanning - an image of the entire portion of the earth's surface that is accessible to it at a given moment, even if it overflows from the region of interest, after which the pixels "Surplus" (outside the RI area of interest) are simply eliminated. This method is not optimal, because it makes spend unnecessarily time for the acquisition of the pixels outside region of interest. It is therefore more advantageous to use two identical satellites, but having different image acquisition laws and variables over time depending on the position of the satellites, so that each satellite acquires only pixels to inside the region of interest. Such programming is complex, but perfectly deterministic and predictable, and can therefore be defined once and for all according to the position of the satellite in its orbit, therefore simply as a function of time. An example of such a programming consists, from the total area accessible at a given moment by a satellite, to subtract the part out of region of interest, and to redefine the image acquisition law of the instrument (eg, by scanning) so that at the end of the image acquisition only the region of interest is acquired. For example, we think of a law of acquisition by scanning successive lines, each line of which would be interrupted as soon as it meets the frontier of the region of interest, allowing without going further to immediately restart the next line inside. of the region ("constrained programming by the usable area"). In the case of an imaging instrument whose operation would, however, require regular aiming of the space beyond the terrestrial edge for purposes such as calibration of the detectors, however, the scanning can be extended to Earth edges for this purpose, only at times when calibration will become essential. In the general case of two or more satellites located in any positions on their orbits, the acquisition times of the areas assigned to each are potentially different. The constrained programming by the usable area can also be applied if the two satellites are not identical. Another example of a constraint of the programming, which can be cumulated with the preceding one, consists in defining the observation regions, and the scanning path in the case of a scan acquisition, so that the set of pixels obtained is as homogeneous as possible temporally. In other words, it is a question of choosing, from among all the possible scans covering the entire region of interest, that giving a final image in which the difference between the acquisition dates of any two pixels is minimal. This can be obtained in particular by allocating to each satellite a portion of the region of interest to be covered such as the time taken by each satellite to obtain the image of this portion being identical to or close to that put by the other satellite for the other portion. Another criterion, alternative or complementary, can consist in choosing, when a point of the region of interest is seen by two satellites, the pixel acquired by that of the 30 satellites whose ground projection (sub-satellite point) is the closer to said point of the region of interest. This choice makes it possible to minimize the scanning time while giving priority to the quality of the shot (all the better that the observed point is close to the sub-satellite point) Any other criterion allowing to cut a target zone in two parts of time Likewise, it is advantageous to choose the scans used by each satellite in such a way that the acquisition of the first pair of partial images begins near the gaps. cover, and that the acquisition of the second (or last) pair of partial images ends near said gaps, which has the effect that between the beginning of the first image (acquisition near the gap) and the end of the second image (acquisition again near the gap) the longest time has elapsed, this is interesting because the rotation of the Earth between the beginning of the first imagery and the The end of the second will have induced a greater displacement of the coverage gaps relative to the earth's surface, making it possible to fill larger gaps, and thus to further relax the constraints on the orbit of the satellites. So far, only the case of a two-satellite system in which each final image is made up of two or three pairs of partial images has been considered, but this is not a limitation. essential. Indeed, the space segment of the observation system can comprise any number - strictly greater than one - of satellites. For example, we can consider the case of a system with three satellites of which only two at the most observe the region of interest at any moment. We can also consider a system in which, at certain times, three or more satellites share the observation of the region of interest. In addition, variants of the method of the invention may be considered in which more than three partial satellite images are acquired. Alternatively, it is possible to insert "zooms" on a critical region (for example during a dangerous local meteorological episode) within the normal cycle; a "usual" image acquisition plan can be designed more generally, with margins designed to allow such "zooms" in the event of a dangerous weather event (or any other critical event to be observed quickly). The region of interest need not be spherical cap-shaped, nor be limited to the circumpolar regions, although this is a preferred embodiment of the invention; for example, it can be defined by the territories and territorial waters of a given country or group of countries. In addition, it is not essential that the satellites move along one or more inclined orbits. On the contrary, the invention can also be implemented by means of satellites moving in an orbit located substantially in an equatorial plane. It could be, for example, two microsatellites (or more) launched as passengers on a geostationary transfer orbit firing with a period of 12h.15
    权利要求:
    Claims (13)
    [0001]
    REVENDICATIONS1. A method of observing a region of the earth's surface, said region of interest (RI), implementing a plurality of satellites (SAT1, SAT2) moving along at least one moving orbit (0), said method comprising: - acquiring by at least two of said satellites, during a same passage over said region of interest and during successive acquisition periods, a plurality of images of the surface terrestrial, 10 said partial images, each covering a portion (R01, R02) of said region of interest; and obtaining an image covering the whole of said region of interest by merging at least two said partial images, having a predefined time offset between their acquisition periods, for each of said at least two satellites.
    [0002]
    2. Method according to claim 1 wherein partial images, said of the same rank, are acquired at the same time by said satellites; the number of said satellites, said or each said moving orbit and said acquisition periods being chosen so that partial images of the same rank, taken in combination, provide a partial coverage of said region of interest, having gaps cover (LC).
    [0003]
    The method of claim 2 wherein said partial images are scanned and, upon acquisition of a first set of partial images of the same rank, said scanning begins in proximity to said coverage gaps, while when subsequently acquiring a second set of partial images of the same rank, said scanning terminates near said coverage gaps 30
    [0004]
    4. Method according to one of the preceding claims wherein each said partial image is obtained by scanning a respective observation region (R01, R02), determined so that it does not exceed said region of interest.
    [0005]
    5. Method according to one of the preceding claims 5 implementing exactly two satellites.
    [0006]
    6. Method according to one of the preceding claims wherein said satellites are spaced along the same scrolling orbit (0). 10
    [0007]
    7. Method according to one of the preceding claims, wherein said image covering all of said region of interest is obtained by merging exactly two said partial images for each of said satellites, acquired during successive acquisition periods. 15
    [0008]
    8. Method according to one of the preceding claims, wherein said region of interest has a spherical cap shape.
    [0009]
    The method according to one of the preceding claims, wherein said or each said traveling orbit is an inclined high elliptical orbit - of the HEO type - and said region of interest is constituted by a portion of terrestrial surface having a higher latitude or equal to a limit value L with I 50 ° and preferably L 60 °.
    [0010]
    10. Method according to one of the preceding claims 25 also comprising an operation of assigning, to each pixel of each said partial image, a set of information representative of a moment of acquisition and a point of the terrestrial surface corresponding to said pixel, and wherein said set of information is used when merging said partial images. 30
    [0011]
    11. Ground segment comprising: at least one satellite receiver (RS) configured to receive, from at least two satellites (SAT1, SAT2) spaced along the same moving orbit, signals representative of images of the earth's surface, said partial images, each covering a portion (R01, R02) of the same region of interest (RI) and acquired during successive acquisition periods during the same passage of said satellites above said region of interest. interest; and - a data processor (PD) configured to merge at least two said partial images for each of said at least two satellites, said partial images received from each said satellites having a predefined time offset between their acquisition periods, in order to obtain an image covering all of said region of interest.
    [0012]
    12. A satellite system for observing a region of the earth's surface, called a region of interest (RI), comprising: a space segment comprising a plurality of satellites (SAT1, SAT2) traveling along at least one a scrolling orbit (0), configured to acquire, during the same passage over said region of interest and during successive acquisition periods, a plurality of images 20 of the terrestrial surface, called partial images, covering each a portion (R01, R02) of said region of interest, and for transmitting said partial images to a ground segment; and - a ground segment according to claim 11. 25
    [0013]
    13. The system of claim 12 wherein said or each said scrolling orbit is a high elliptical orbit - HEO type - and said region of interest is constituted by all the points of the terrestrial surface having a latitude greater than or equal to a value. limit 1.50 ° and preferably L _60 °. 30
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
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    FR1401509A|FR3023435B1|2014-07-04|2014-07-04|METHOD FOR OBSERVING A REGION OF THE GROUND SURFACE, PARTICULARLY LOCATED WITH HIGH LATITUDES; SOIL STATION AND SATELLITE SYSTEM FOR IMPLEMENTING SAID METHOD|FR1401509A| FR3023435B1|2014-07-04|2014-07-04|METHOD FOR OBSERVING A REGION OF THE GROUND SURFACE, PARTICULARLY LOCATED WITH HIGH LATITUDES; SOIL STATION AND SATELLITE SYSTEM FOR IMPLEMENTING SAID METHOD|
    EP15175059.3A| EP2962943B1|2014-07-04|2015-07-02|Method for observing a region of the earth's surface, in particular located at high latitudes; ground station and satellite system for implementing said method|
    US14/790,843| US11050950B2|2014-07-04|2015-07-02|Method for observing a region of the earth's surface, notably located at high latitudes; ground station and satellite system for implementing this method|
    CA2896205A| CA2896205A1|2014-07-04|2015-07-03|Method for observing a region of the earth's surface, notably located at high latitudes; ground station and satellite system for implementing this method|
    CL2015001908A| CL2015001908A1|2014-07-04|2015-07-03|Procedure for observing a region of the earth's surface, in particular at high latitudes; ground station and satellite system for the implementation of this procedure.|
    ARP150102151A| AR101546A1|2014-07-04|2015-07-03|OBSERVATION PROCEDURE OF A REGION OF THE GROUND SURFACE, IN PARTICULAR LOCATED TO ELEVATED LATITUDES; SOIL STATION AND SATELLITE SYSTEM FOR THE PRACTICE OF THIS PROCEDURE|
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