A compact spaceborne cloud detection and identification camera and satellite

Abstract

The application discloses a small cloud detection and identification camera and satellite, and relates to optical measurement and metrology. The application comprises a lens group, a pre-filter arranged on the image side of the lens group, the pre-filter being a double-channel narrow-pass filter, a color detector arranged on the other side of the pre-filter, the color detector being a surface array imaging detector adopting a Bayer filter, a processing circuit in communication connection with the color detector, used for receiving detection data of the color detector and performing image identification, and a support structure provided with an inner cavity matched with the support structure, the lens group, the pre-filter, the color detector and the processing circuit, wherein the lens group, the pre-filter, the color detector and the processing circuit are arranged in the inner cavity, so that the problem that the existing cloud judgment method and load cannot completely meet the on-orbit use requirement of high-resolution remote sensing imaging satellites is solved.

Description

Technical Field

[0001] This invention belongs to the field of optical measurement and metrology, and in particular relates to a small spaceborne cloud detection and identification camera and satellite. Background Technology

[0002] The presence of numerous clouds in high-resolution optical remote sensing data affects the quality of remote sensing images, thereby reducing data utilization, wasting valuable satellite data transmission bandwidth, and even impacting the lifespan of some satellites. According to global cloud cover data provided by the International Satellite Cloud Climatology Project (ISCCP), clouds cover more than 60% of the Earth's surface. Therefore, cloud detection and identification are crucial in the field of high-resolution optical remote sensing satellites for Earth observation.

[0003] Current cloud detection and removal by Earth-based optical remote sensing satellites primarily relies on ground-based processing. This involves receiving satellite images from the ground, performing cloud detection, classification, and removal, and then further processing to obtain satellite data products. The main drawback of this ground-based processing method is that the satellite images, already transmitted to the ground, contain a large amount of invalid image data, wasting transmission bandwidth and sacrificing the satellite's limited imaging time. Therefore, real-time cloud identification in orbit has become an important development trend in recent years.

[0004] Currently, on-orbit cloud detection primarily utilizes the imaging capabilities of the satellite's main camera, removing cloud components through image processing. However, due to the limited on-orbit processing capabilities of high-resolution images, and the fact that the main camera is not designed for cloud detection, problems such as saturation and high false positive rates exist, hindering technological breakthroughs. Deploying dedicated cloud detection payloads is another feasible approach. However, existing cloud detection payloads are overly complex, primarily used in meteorological remote sensing, and not suitable for remote sensing imaging satellites. In conclusion, existing cloud detection methods and payloads cannot fully meet the on-orbit usage requirements of high-resolution remote sensing imaging satellites.

[0005] Therefore, it is essential to design a cloud determination method and payload that are suitable for high-resolution remote sensing imaging satellites. Summary of the Invention

[0006] The purpose of this invention is to provide a small cloud detection and identification camera and satellite. By combining a pre-filter and a Bayer filter and using a dual-band cloud identification algorithm for cloud detection and identification, it solves the problem that existing cloud judgment methods and payloads cannot fully meet the on-orbit usage requirements of high-resolution remote sensing imaging satellites.

[0007] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0008] This invention provides a small cloud detection and identification camera, comprising:

[0009] case;

[0010] A lens assembly, a pre-filter, and a color detector are sequentially installed within the housing along the main optical axis.

[0011] A processing circuit, communicatively connected to the color detector, is used to receive the detection data from the color detector and perform cloud identification.

[0012] The pre-filter is a dual-channel narrow-pass filter, and the color detector is an area array imaging detector using a Bayer filter.

[0013] In one embodiment of the present invention, the center wavelengths of the two channels of the pre-filter are 465nm±15nm and 750nm±15nm, respectively; the bandwidth range is 1nm~20nm.

[0014] In one embodiment of the present invention, the type of Bayer filter used in the color detector includes RGGB, RGBW and RYYB.

[0015] In one embodiment of the present invention, the support structure is disposed within the housing along the main optical axis, and the lens group, pre-filter and color detector are sequentially installed within the support structure along the main optical axis.

[0016] In one embodiment of the present invention, the pre-filter is disposed close to the color detector.

[0017] In one embodiment of the invention, a light shield is further included, which is mounted on one end of the support structure near the lens group.

[0018] In one embodiment of the present invention, the angular magnification of the lens group is 2-5 times.

[0019] In one embodiment of the present invention, the housing is further provided with a communication interface, which is connected to the processing circuit and is used to connect the processing circuit with an external circuit so that the processing circuit can communicate with the external circuit.

[0020] In one embodiment of the present invention, the processing circuit performs cloud contour and cloud shape recognition based on a dual-band cloud recognition algorithm.

[0021] To achieve the purposes of this application and other related purposes, this application also provides a satellite that uses a small cloud detection and identification camera as described in any of the preceding claims.

[0022] This invention employs a combination of pre-filters and Bayer filters for filtering, and performs image processing based on a dual-band cloud recognition algorithm. It requires only a single optical channel and has no moving parts to complete cloud recognition, and can utilize existing, relatively mature color detectors, making the overall technical solution simple and reliable. It not only meets the on-orbit cloud identification requirements of high-resolution remote sensing imaging satellites but also improves the accuracy of on-orbit cloud recognition for these satellites. Furthermore, it boasts advantages such as small structural size, low resource consumption, and high reliability.

[0023] This invention, by setting up a light shield, can effectively prevent the lens group from being directly exposed to strong light, reduce halos, and help the camera adapt to harsh environments. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of a small cloud detection and identification camera provided for an exemplary embodiment of this application.

[0026] Figure 2 This is a typical design curve for a color detector in an exemplary embodiment of this application.

[0027] Figure 3 This is a transmittance curve of the pre-filter in an exemplary embodiment of this application.

[0028] Figure 4 This is a quantum efficiency curve of a color detector after passing through a pre-filter in an exemplary embodiment of this application.

[0029] Figure 5 A cross-sectional view of a small cloud detection and identification camera provided for an exemplary embodiment of this application. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] To address the problems of saturation, high false positive rate, and overly complex detection payloads in existing on-orbit cloud detection technologies that are unsuitable for remote sensing imaging satellites, this invention provides a small-scale spaceborne cloud detection and identification camera and satellite. These embodiments will be discussed in detail below.

[0032] Please see Figure 1 As shown in an exemplary embodiment of this application, the small spaceborne cloud detection and identification camera includes: a lens group 1, a pre-filter 2, a color detector 3, a processing circuit 4, and a housing 5. The lens group 1, the pre-filter 2, and the color detector 3 are sequentially mounted within the housing along the principal optical axis. Specifically, the pre-filter 2 is mounted on the image side of the lens group 1, and the color detector 3 is mounted on the side of the pre-filter 2 away from the lens group 1. The processing circuit 4 is communicatively connected to the color detector 3 and is used to receive the detection data from the color detector 3 and perform cloud identification. The pre-filter 2 is a dual-channel narrow-pass filter, and the color detector 3 is an area array imaging detector using a Bayer filter.

[0033] It should be noted that the lens group 1 is used to focus light. The lens group 1 consists of multiple lens elements, which are arranged in a specific order to correct aberrations and improve image quality. In an exemplary embodiment of this application, the angular magnification of the lens group is 2-5 times in order to achieve high-resolution, high-sensitivity observation of the target.

[0034] In an exemplary embodiment of this application, the center wavelength of the channel of the pre-filter 2 needs to be selected based on the transmittance curve of the Bayer filter of the color detector 3. Specifically, the two wavelengths with the least crosstalk are calculated based on the transmittance curve of the Bayer filter, and these wavelengths are selected as the center wavelengths of the channel of the pre-filter 2. In an exemplary embodiment of this application, the center wavelength of one channel of the pre-filter 2 is 465nm and the center wavelength of the other channel is 750nm. Furthermore, the center wavelengths of the two channels of the pre-filter 3 can be adjusted within a certain range relative to the calculation results obtained from the transmittance curve of the Bayer filter to select a more effective scheme. For example, the center wavelength of one channel of the pre-filter 3 can be 450nm, 455nm, 460nm, 465nm, 470nm, 475nm, or 480nm, etc. Similarly, the center wavelength of the other channel can be 735nm, 740nm, 745nm, 750nm, 755nm, 760nm, or 765nm, etc. The bandwidth of the pre-filter is 1nm to 20nm, for example, 5nm, 10nm, 15nm, or 20nm. The pre-filter is cut off in the non-passband region within the range of 350nm to 1100nm.

[0035] It is important to understand that the center wavelength and bandwidth of a channel together determine the channel range. For example, if the center wavelength of the channel is 750nm and the bandwidth is 20nm, then the channel range is 740nm-760nm.

[0036] Please see Figure 2-4 As shown, Figure 2 This is a typical design curve for the color detector in an exemplary embodiment of this application. Figure 3 This is the transmittance curve of the pre-filter 3 described in an exemplary embodiment of this application. Figure 4 The image shows the quantum efficiency curve of the color detector 4 after passing through the pre-filter 3. It can be seen that after filtering by the pre-filter 3, the original three-color peak curve of the color detector 4 is confined to two relatively narrow bands. The G channel is essentially suppressed to 5% of its original value and is therefore discarded in this invention. The R and B channels have their bandwidth compressed by the pre-filter 3. Furthermore, from... Figure 4 It can also be seen that the crosstalk between the channels is small and the out-of-band response is low, which can meet the requirements of dual-channel detection cloud. Among them, the R, G and B channels represent the red light channel, green light channel and blue light channel, respectively.

[0037] In an exemplary embodiment of this application, the color detector is used to convert the received optical signal into an electrical signal to generate detection data, and then sends the detection data to the processing circuit. It should be noted that the color detector in this application includes CCD (Charge-coupled Device) type and CMOS (Complementary Metal Oxide Semiconductor) type, and the Bayer filter used can be of type RGGB, RGBW, RYYB, etc. It should be noted that a Bayer filter is a mosaic color filter array formed by arranging RGB color filters on a grid of light-sensing components. RGGB is a specific arrangement of Bayer filters, where R, G, and B represent red, green, and blue, respectively. In this arrangement, the number of green sub-pixels is typically twice that of red or blue sub-pixels, i.e., 50% green, 25% red, and 25% blue; the RGBW type Bayer filter is an improvement on the traditional RGB Bayer filter. Traditional RGB Bayer filters are primarily used in image sensors, capturing color information through an array of red (R), green (G), and blue (B) filters. RGBW type Bayer filters add a white (W) filter to this structure. RYYB Bayer filters are a new type of filter that improves upon the traditional RGB Bayer filter. They replace the green (G) filter in the RGB array with a yellow (Y) filter, resulting in the RYYB (red, yellow, yellow, blue) arrangement. When light of a certain wavelength passes through a Bayer filter, its wavelength changes, while another wavelength remains unchanged or changes only slightly. This process further filters and adjusts the light, resulting in the final output light with a specific wavelength and polarization state.

[0038] In addition, it should be noted that, in order to improve the parallelism and intensity of light, reduce light attenuation and loss, maintain the compactness and stability of the system, and optimize imaging quality, the distance between the pre-filter and the color detector described in this application should be as small as possible.

[0039] In an exemplary embodiment of this application, the processing circuit 4 receives the detection data from the color detector and analyzes the detection data based on a dual-band cloud recognition algorithm. Specifically, when there are objects in the ground image that are similar in color to clouds, since the reflectivity of ground objects is different from that of clouds, the ratio of dual-band radiance values ​​is used, referring to the surface reflectivity spectral library data, and combined with conventional image processing algorithms, to effectively determine whether a certain pixel contains clouds, and to distinguish cloud outlines or cloud shapes.

[0040] In an exemplary embodiment of this application, the housing is further provided with a communication interface, which is connected to the processing circuit and used to connect the processing circuit and an external device. The processing circuit is communicatively connected to the external device and communicates with the outside to send data information such as recognition results to other external devices, receive instructions from external devices, or perform other functions.

[0041] Please see Figure 5 As shown, in an exemplary embodiment of this application, a support structure is provided inside the housing, and the support structure is disposed inside the housing along the main optical axis. The lens group 1, the pre-filter 2, and the color detector 3 are sequentially installed inside the support structure along the main optical axis.

[0042] Please see Figure 5 As shown in the exemplary embodiment of this application, a light shield 7 is also installed at one end of the support structure 6 near the lens group 1. The light shield 7 is arranged around the main optical axis, with one end connected to the support structure 6 and the other end extending away from the lens group 1. The shape of the light shield 7 is partially conical or partially pyramidal. The connection method between the light shield 7 and the support structure 6 can be a snap-fit ​​connection, screw-in connection, snap-fit ​​connection, twist-lock connection, or adapter connection, etc. Of course, the light shield 7 and the support structure 6 can also be an integral structure. Of course, in other embodiments, the shape of the light shield 7 can also be other approximate shapes, and the light shield 7 can also be disposed on the housing 5.

[0043] During operation, light first passes through lens group 1, where it is focused by refraction. Next, the light passes through pre-filter 2. Since pre-filter 2 is a dual-channel narrow-pass filter, only light with wavelengths within the channel range can pass through it; other wavelengths are filtered out. Then, the light passes through the Bayer filter of the color detector 3. When the light selected by pre-filter 2 enters the Bayer filter, its wavelength is further adjusted. Specifically, the wavelength of one wavelength changes after passing through the Bayer filter, while another wavelength remains unchanged or changes only slightly. This process further filters and adjusts the light, resulting in a final output light with a specific wavelength and polarization state. The light is then received by the photosensitive element of the color detector 3. The photosensitive element uses the photoelectric effect to convert the light signal into an electrical signal to generate detection data, which is then sent to the processing circuit 4. After receiving the detection data, the processing circuit 4 analyzes and processes the detection data based on the dual-band cloud recognition algorithm to finally obtain the required cloud outline and cloud morphology data.

[0044] In summary, this application employs a combination of pre-filter 2 and Bayer filter for filtering, and performs image processing based on a dual-band cloud recognition algorithm. It requires only a single optical channel and requires no moving parts to complete cloud recognition, and can utilize the relatively mature color detector 3 from existing technologies, making the overall technical solution simple and reliable. This not only meets the on-orbit cloud identification requirements of high-resolution remote sensing imaging satellites but also improves the accuracy of on-orbit cloud recognition for high-resolution remote sensing imaging satellites, and has advantages such as small structural size, low resource consumption, and high reliability.

[0045] Throughout this description, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of embodiments of this application. However, those skilled in the art will recognize that embodiments of this application may be practiced without one or more of these specific details or by other devices, systems, components, methods, parts, materials, components, etc.

[0046] It should also be understood that one or more of the elements shown in the figures may be implemented in a more separate or more integrated manner, or may even be removed because they are inoperable in certain circumstances or provided because they may be useful for a particular application.

[0047] Furthermore, unless otherwise expressly stated, any arrows in the accompanying drawings should be considered illustrative only and not limiting. Additionally, unless otherwise stated, the term "or" as used herein is generally intended to mean "and / or". Where a term is anticipated to provide a separation or combination capability that is unclear, a combination of components or steps will also be considered as indicated.

[0048] The above description of the embodiments shown in this application (including the content set forth in the abstract of the specification) is not intended to be an exhaustive enumeration or to limit this application to the precise forms disclosed herein. Although specific embodiments and examples of this application have been described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of this application, as will be recognized and understood by those skilled in the art. As indicated, these modifications can be made to this application in accordance with the above description of the embodiments described herein, and such modifications will be within the spirit and scope of this application.

[0049] This document has generally described the systems and methods in detail to aid in understanding the present application. Furthermore, various specific details have been provided to offer a general understanding of the embodiments of this application. However, those skilled in the art will recognize that embodiments of this application can be practiced without one or more specific details, or using other means, systems, accessories, methods, components, materials, parts, etc. In other instances, well-known structures, materials, and / or operations have not been specifically shown or described in detail to avoid obscuring various aspects of the embodiments of this application.

[0050] Therefore, although this application has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are also within the scope of the above disclosure, and it should be understood that in some cases, certain features of this application may be adopted without departing from the scope and spirit of the invention and without corresponding use of other features. Thus, many modifications can be made to adapt a particular environment or material to the essential scope and spirit of this application. This application is not intended to be limited to the specific terminology used in the following claims and / or the specific embodiments disclosed as the best mode of carrying out this application, but this application will include any and all embodiments and equivalents falling within the scope of the appended claims. Therefore, the scope of this application will be determined only by the appended claims.

[0051] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0052] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A small cloud detection and identification camera, characterized in that, include: case; A lens assembly, a pre-filter, and a color detector are sequentially installed within the housing along the main optical axis. The processing circuit is communicatively connected to the color detector. The processing circuit is used to receive the detection data from the color detector and to identify cloud outlines and cloud shapes according to the dual-band cloud recognition algorithm. The pre-filter is a dual-channel narrow-pass filter, and the color detector is an area array imaging detector using a Bayer filter. The center wavelength of the channel of the pre-filter is selected according to the transmittance curve of the Bayer filter of the color detector. The two wavelengths with the least crosstalk are calculated according to the transmittance curve of the Bayer filter, and the wavelengths are selected as the center wavelengths of the channel of the pre-filter.

2. The small cloud detection and identification camera according to claim 1, characterized in that, The center wavelengths of the two channels of the pre-filter are 465nm±15nm and 750nm±15nm, respectively; the bandwidth range is 1nm~20nm.

3. The small cloud detection and identification camera according to claim 1, characterized in that, The color detector uses one of the following types of Bayer filters: RGGB, RGBW, and RYYB.

4. The small cloud detection and identification camera according to claim 1, characterized in that, It also includes a support structure, which is disposed within the housing along the main optical axis, and the lens group, pre-filter and color detector are sequentially installed within the support structure along the main optical axis.

5. The small cloud detection and identification camera according to claim 4, characterized in that, It also includes a light shield, which is mounted on one end of the support structure near the lens group.

6. The small cloud detection and identification camera according to claim 1, characterized in that, The pre-filter is positioned close to the color detector.

7. The small cloud detection and identification camera according to claim 1, characterized in that, The angular magnification of the lens group is 2-5 times.

8. The small cloud detection and identification camera according to claim 1, characterized in that, The housing is also provided with a communication interface, which is connected to the processing circuit. The communication interface is used to connect the processing circuit with an external circuit so that the processing circuit can communicate with the external circuit.

9. A satellite, characterized in that, The satellite uses a small cloud detection and identification camera as described in any one of claims 1-8.

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