• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The method comprises at least the following steps: a step of data acquisition by said radar to obtain said SAR image (1) covering a given geographical area; a step of acquiring at least one secondary image (2, 3) covering said domain produced by a source (4, 5) external to the radar, said image providing color information of the elements composing said SAR image; a superposition step of said SAR image and said secondary image; a step of assigning colors to said elements as a function of their position in said superimposed secondary image.
    公开号:FR3037660A1
    申请号:FR1501260
    申请日:2015-06-17
    公开日:2016-12-23
    发明作者:Patrick Garrec；Vincent Corretja；Julien Petitjean；Richard Montigny
    申请人:Thales SA；
    IPC主号:
    专利说明:

    [0001] 1 METHOD OF COLORING SAR IMAGES. The present invention relates to a method for colorizing SAR images. It applies for example for multifunctional airborne radars 5 performing SAR images. The images produced by radars with synthetic aperture, also called SAR images according to the English terminology, make it possible in particular to obtain views in all weather, day and night, can even penetrate certain surfaces or certain environments, such as vegetation, making these surfaces or media transparent. They therefore have an advantage over optical images. A disadvantage of these SAR images is their lack of realistic colorization. They make it possible to distinguish forms and shadows, but with arbitrary colors. Their exploitation or analysis is therefore not simple, the interpretation of the elements of these images requiring training or learning. Colorization solutions are known but the colors attributed to the components of the SAR image are arbitrary, the image being in false colors. In these solutions, the HH channels are for example in red, the HV channels in green and the VV channels in blue, H corresponding to the horizontal polarization and V to the vertical polarization. These colors do not have a goal of realism, they are simply used to facilitate the technical analysis by a specialist. In no way, these colors are intended to facilitate interpretation by a simple, non-specialist operator. Current SAR images therefore require extensive operator training to interpret and analyze them. The interpretation of a SAR image is indeed very different from that of an image acquired by an optical sensor. They are in fact without color. They give information relating to the roughness of the sensed surface. An operator accustomed to seeing conventional video is taken aback by the representation produced by a SAR image. An object of the invention is to overcome this disadvantage, in particular by enabling exploitable colorization of a SAR image, that is to say 3037660 comprehensible by any operator. For this purpose, the subject of the invention is a method for colorizing SAR images produced by a radar, for colorizing a SAR image, said method comprising at least the following steps: a step of data acquisition by said radar for obtaining said SAR image covering a given geographical area; a step of acquiring at least one secondary image covering said domain produced by a source external to the radar, said image providing color information of the elements composing said SAR image; a superposition step of said SAR image and said secondary image; a step of assigning colors to said elements according to their position in said superimposed secondary image.
    [0002] In one possible embodiment, said external source is a prerecorded image file, the prerecorded images being for example provided by a search engine. Said external source is for example a digital terrain model, said secondary image being a representation of said domain in said model. Said external source may also be for example an optical sensor embedded on the carrier of said radar. Other features and advantages of the invention will become apparent with the aid of the description which follows, given with reference to the appended drawings which represent: FIG. 1, an illustration of the principle of the invention; FIG. 2, a presentation of possible steps for implementing the method according to the invention; Figures 3a to 3d, an example of application of the method according to the invention. FIG. 1 illustrates the principle of the method according to the invention. Advantageously, in order to produce the images, the invention exploits secondary images 2, 3 from sources other than radar capture, and couples these images with the data 1 acquired by the radar, the colors being obtained by means of these data 2, 3. To obtain the conventional colorless SAR image, hereinafter referred to as the basic SAR image or the raw image, the method uses the conventional means of obtaining otherwise well-known SAR images. In the exemplary implementation illustrated in FIG. 1, the method uses two sources of external images: data 2 coming from a digital terrain model, called DTM, giving a particular representation of the domains covered by the images. SAR; images 3 provided by a search engine 5, which may also be referred to hereafter as external images. These representations are for example known a priori. The DTM data sources or the search engine are in a certain way entities providing a priori knowledge of the locations imaged by the radar, this a priori knowledge being intended to be coupled with the SAR images produced in real time. The DTM data are for example stored in a file 4, the other data 3 being accessible by the search engine 5, also in real time, or by storage by the radar processing means.
    [0003] The radar processing means 6 exploit the data 1 acquired by the radar, the DEM data and the data from the search engine. The radar data makes it possible to obtain the basic SAR image in a known manner. The DTM data notably makes it possible to obtain an altitude-based representation of the elements composing the SAR image. The images provided by the search engine make it possible to obtain the texture of these elements. The data acquired by the radar is used to locate the scene or geographic area imaged. In particular, the geographic coordinates of the SAR image are obtained by the georeferencing system of the platform carrying the radar. From this geographical location of the domain, it is therefore possible to acquire the secondary images covering this domain in the MNT 5 model and from the search engine. The provider entities then provide texture characteristics, for the search engine, and altitude for the DTM file 4, all of this information for assigning colors to the various elements composing the SAR image. The secondary images, formed from the DEM images and the external images from the search engine, are input data of the radar processing 6. The colorization of a SAR image is obtained by superimposing this image with the DEM images and the external image. The access to the DEM data is done by means of an appropriate interface between the file 4 and the processing means 6. The access to the data of the search engine is done either by a suitable internet communication or by an interface adapted to a file storing these data or equivalent data. The principle of the invention having been illustrated in FIG. 1, FIG. 2 presents the various possible steps of the method according to the invention.
    [0004] Figure 2 thus illustrates the possible steps for colorizing a SAR image covering a given geographical area. It applies in the same way for all SAR images.
    [0005] In a first step 21, the radar acquires the data to obtain the basic SAR image, covering the geographical domain. This first step 21 is followed by a step of acquiring at least one secondary image supplied by a source external to the radar. An external source to the radar is a source that provides image data that does not involve radar detection. This secondary image gives color information for the elements composing the basic SAR image. As previously indicated, this information may be texture information if the external source is a search engine or altitude information if the external source is a DTM terrain digital model. As in the example of Figure 1, it is possible to provide two or more external sources. Another external source may for example be an optical sensor embedded on the radar carrier, the data received by the sensor then being transferred to the radar processing means. In a next step 23, the processing means superimposes the basic SAR image with the secondary image produced by the external source. If several external sources are used, the overlay relates to all the secondary images with the SAR image. In this case, each secondary image can be superimposed with the SAR image. So if there are two secondary images, two overlays are performed. The overlay consists of comparing the digital data constituting an image of the domain. Overlay methods will be described later. In a next step 24, colors are assigned to the different elements of the SAR image next to the result of the superposition of the images. For example, if the representation DTM indicates that an area of the image corresponds to a surface of water, the sea in particular, the zone can be colored in blue. The image provided by the search engine gives for example more nuanced information on the texture of the elements. The colors assigned in the final may be arbitrary or not, and are intended in particular to make the SAR image more comprehensible. Several solutions can be used to superimpose the secondary image (s) with the SAR image. To superimpose all these representations, SAR image, DTM image and external image, it is necessary to readjust them geographically and put them all on the same scale. In a first solution, the different images can be referenced with respect to a singular point present in the SAR image and in the secondary images. The radar processing means may use GPS information to reference the different images with respect to this singular point. In particular, the GPS coordinates of the singular point 3037660 are used, these coordinates being the reference coordinates for all the superimposed images. The SAR images are for example corrected with respect to the secondary images, DEM and others, by correlation in the image. As indicated above, the geographical coordinates of a SAR image are for example obtained by the carrier's geo-referencing system. A division, in zones, of secondary images, DTM and others, is carried out thanks to these geographical coordinates in order to superimpose the images, the corresponding zones between images being superimposed. A registration is performed by adapting the size of the secondary images by stretching the data of the secondary images corresponding to the georeferencing of the data of the SAR image, the stretch corresponding to a change of scale. The data of the images are in particular the pixels 15 or the altitude data for the representation DTM. Stretching affects the positions of the pixels or altitude measurement points in the image. Once this cutting is done, it may be necessary to superimpose the two images. This superposition is done for example on remarkable points. The images being digital, the superposition 20 can also be done by a numerical correlation of the two images, the SAR image and the secondary image, making it possible to measure the displacements between the two images. For this purpose, for example, a video-type secondary image, derived from a search engine or an optical sensor, may in particular be converted into gray levels for greater ease, and then by stretching. In addition, a Laplacian operator of order 1 is used to more precisely determine the contours of the objects or elements of the images according to known techniques, with respect to a mean threshold. Once the dimensions have been adjusted, and thus the superposition performed in the corresponding step 23, the color assignment on the elements of the SAR image can be done in the next step 24 by a point-to-point correlation, making match the hue information (red, green and blue of the digital encoding) retrieved from the secondary image. The intensity is applied using, for example, directly the information from the SAR image.
    [0006] For example, a conventional contour treatment is performed to prevent the colors from overflowing outlines. Color intensity gradient use is for example effected by labeling the zones of the SAR image by uniqueness of color, the color being uniform over an entire area. For a moving target present on a SAR image, we do not know a priori its color, at least in the general case. Indeed, this target is not present in the secondary images that are prerecorded, in particular for images from search engines or DEM models. In a treatment in the presence of moving targets, they are dynamically recalibrated on the SAR image and an arbitrary color can be assigned to them, this color must be different from the background to help their visualization.
    [0007] In the case where the secondary image is produced by an optical sensor in real time, the moving targets can be labeled with colors in relation to the colors of the actual target. In a colorization variant, to optimize the color, the colors from the search engine file are used, for example, and the intensity of the color is adjusted in proportion to the intensity of the backscattered signal in the SAR image. All these treatments for colorizing the SAR images using external image sources can be performed by the radar processing means 6 without any particular arrangement. Only a few additional communications interfaces are expected, possibly. FIGS. 3a to 3d illustrate, by way of example, the coloration of a SAR image 30 according to the invention, with the aid of secondary image files, more particularly with the aid of a DTM file or with the using a prerecorded image provided by a search engine. Figure 3a shows the SAR basic image at the radar processing output. The optical image of the imaged area is given in Figure 3b. Figure 3c shows the image provided by the search engine. The MNT file 3037660 8 corresponding to the image area 31 is also available. By distinguishing the land 32 from the sea 33 thanks to the DTM file, we arrive at the colorized image presented by the figure 3d. In this example of colorization, the sea is represented in blue and the earth in red. The invention advantageously makes it possible to trivialize and simplify the training of the operators who will thus be able to concentrate more on their mission thanks to a lesser effort of interpretation of the images. 5 10
    权利要求:
    Claims (5)
    [0001]
    REVENDICATIONS1. A method of colorizing SAR images produced by a radar, characterized in that for the colorization of a SAR image, said method comprises at least the following steps: a step (21) of data acquisition by said radar to obtain said SAR image (1, 30) covering a given geography domain (31); a step (22) for acquiring at least one secondary image (2, 3) covering said domain produced by a source (4, 5) external to the radar, said image providing color information of the elements composing said image SAR; a step (23) of superposition of said SAR image and said secondary image; a step (24) of assigning colors to said elements according to their position in said superimposed secondary image.
    [0002]
    2. Method according to claim 1, characterized in that said external source is a prerecorded image file (5).
    [0003]
    3. Method according to claim 2, characterized in that the prerecorded images are provided by a search engine.
    [0004]
    4. Method according to any one of the preceding claims, characterized in that said external source is a digital terrain model (4), said secondary image being a representation (2) of said domain in said model. 25
    [0005]
    5. Method according to any one of the preceding claims, characterized in that said external source is an optical sensor embedded on the carrier of said radar. 30
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    同族专利:
    公开号 | 公开日
    FR3037660B1|2020-01-31|
    US20180210078A1|2018-07-26|
    EP3311187A1|2018-04-25|
    WO2016202662A1|2016-12-22|
    引用文献:
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    EP2180337A1|2007-08-17|2010-04-28|PASCO Corporation|Terrestrial object information judging image producing method and program|
    WO2015192056A1|2014-06-13|2015-12-17|Urthecast Corp.|Systems and methods for processing and providing terrestrial and/or space-based earth observation video|
    US10871561B2|2015-03-25|2020-12-22|Urthecast Corp.|Apparatus and methods for synthetic aperture radar with digital beamforming|
    CN108432049B|2015-06-16|2020-12-29|阿卜杜拉阿齐兹国王科技城|Efficient planar phased array antenna assembly|
    CA3044806A1|2015-11-25|2017-06-01|Urthecast Corp.|Synthetic aperture radar imaging apparatus and methods|
    法律状态:
    2016-05-26| PLFP| Fee payment|Year of fee payment: 2 |
    2016-12-23| PLSC| Publication of the preliminary search report|Effective date: 20161223 |
    2017-05-30| PLFP| Fee payment|Year of fee payment: 3 |
    2018-05-29| PLFP| Fee payment|Year of fee payment: 4 |
    2019-06-03| PLFP| Fee payment|Year of fee payment: 5 |
    2020-05-26| PLFP| Fee payment|Year of fee payment: 6 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1501260A|FR3037660B1|2015-06-17|2015-06-17|COLORING PROCESS FOR SAR IMAGES|
    FR1501260|2015-06-17|FR1501260A| FR3037660B1|2015-06-17|2015-06-17|COLORING PROCESS FOR SAR IMAGES|
    EP16731045.7A| EP3311187A1|2015-06-17|2016-06-08|Method for colouring sar images, and radar capable of implementing such a method|
    US15/576,246| US20180210078A1|2015-06-17|2016-06-08|Method for colouring sar images, and radar capable of implementing such a method|
    PCT/EP2016/063026| WO2016202662A1|2015-06-17|2016-06-08|Method for colouring sar images, and radar capable of implementing such a method|
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