Modular camera 4pi imaging device with sparse sampling

Abstract

The application relates to a combined module camera full-sky 4pi single-rotation sparse sampling imaging device, which comprises a plurality of module cameras, a periodic rotation execution mechanism, a periodic rotation execution mechanism controller, a wireless signal transmission device and a central machine. The combined module camera full-sky 4pi single-rotation sparse sampling imaging device is innovative in that a ring 2pi space imaging system with different topological combinations is constructed by using module cameras, and the imaging system is arranged on the same great circle plane of the sky. During imaging, the module cameras are controlled to rotate around a fixed axis and take pictures at a specific frequency, so that a precise time sequence scanning image sequence is obtained without special reset adjustment. The central machine processes the shooting results of the precise time sequence scanning image sequence according to estimated scene information, and a full-sky image containing four-dimensional space-time information is obtained.

Description

Technical Field

[0001] This invention relates to the field of space optical remote sensing technology, and in particular to an imaging device for sparse sampling of the entire celestial sphere using a combined modular camera with 4π individual rotation. Background Technology

[0002] In the complex space environment, high-speed debris, navigation stars, and artificial objects are scattered across the entire celestial sphere, urging remote sensing spacecraft to further expand their observation range. Currently, achieving 4π-dimensional celestial imaging primarily relies on wide-angle equipment acquisition, multi-camera spherical stitching, and multi-dimensional scanning. Chinese patent document CN105530415B, "Large Target Low-Light Celestial Camera System," proposes a panoramic imaging method based on a 220° field-of-view lens. However, due to the limitations of the spatial bandwidth product of optical systems, wide-angle equipment such as fisheye lenses suffer from significant distortion and blurred image quality, making it difficult to meet the high-precision, accurate positioning data acquisition requirements of the space optical remote sensing field. Multi-camera panoramic stitching, such as in Chinese patent document CN107608164A, requires a large number of cameras and is difficult to adjust according to mission needs. Furthermore, domestic and international research on celestial imaging mainly focuses on fields such as automotive navigation, lacking research specifically for the space optical remote sensing field. Chinese patent document CN113781885B proposes a 4π spatial target detection method that uses a camera outer frame and a rigid rotor for three-dimensional scanning. However, the structure and motion are relatively complex, and there are problems such as the superposition of three-axis rotation errors, which limits the imaging accuracy and frequency. Summary of the Invention

[0003] To address the technical challenge of achieving high-precision, low-distortion imaging in the 4π space of the entire celestial sphere in existing technologies, this invention provides an imaging device that uses a combined modular camera for sparse sampling of the 4π space of the entire celestial sphere through individual rotation.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0005] An imaging device using a combined modular camera with 4π individually rotated sparse sampling across the entire celestial sphere, comprising:

[0006] Multiple modular cameras, a periodic rotary actuator, a periodic rotary actuator controller, a wireless signal transmission device, and a central unit;

[0007] Multiple modular cameras are connected by a connecting mechanism and combined on the same plane to form a ring 2π spatial imaging system; the ring 2π spatial imaging system is mounted on a periodic rotary actuator, which has a single-axis 360° rotational degree of freedom.

[0008] The controller for the periodic rotary actuator is used to set the rotational speed and starting point of the periodic rotary actuator;

[0009] The wireless signal transmission device is used to transmit signals between the central unit and the module camera and the controller of the periodic rotary actuator;

[0010] The central unit calculates the operating parameters of the rotating actuator controller and multiple modular cameras based on the imaging task and sends them to the corresponding modules;

[0011] The controller of the periodic rotary actuator is connected to the periodic rotary actuator via a data cable; signals are transmitted between the controller and the periodic rotary actuator via the data cable.

[0012] The central computer processes the precise temporal scan image sequence based on the estimated location and distance of objects to obtain a full-sky 4π spatial image.

[0013] In the above technical solution, in the 2π ring space imaging system, the half-field angle of the imaging unit is θ, and the angle between the imaging unit and the diagonal of the module camera is the imaging unit mounting angle ε; at this time, the angle interval Δρ between two adjacent imaging operations in the 2π ring space imaging system satisfies:

[0014] Δρ≤arccos(cos(2θ) / cos(2ε)).

[0015] In the above technical solution, each module camera is equipped with two imaging units.

[0016] In the above technical solution, the module camera parameters and imaging angle intervals are determined by calculating the module camera blind zone.

[0017] In the above technical solution, ε is the imaging unit mounting angle, θ is the half field of view angle, a is the side length of the module camera, and the scene distance L should satisfy: L≥L1∧L≥L2

[0018] in:

[0019]

[0020] L1 is the center distance of the diagonal blind zone, the length of the intersection between the blind zone and the extended diagonal line of the module camera, and L2 is the length of the intersection between the blind zone and the extended boundary line of the module camera, the center distance of the boundary blind zone.

[0021] The present invention has the following beneficial effects:

[0022] This invention presents an imaging device for sparse sampling of the entire celestial sphere using a combined modular camera with 4π individually rotated cameras. It innovatively proposes constructing a 2π-ring spatial imaging system with different topological combinations using modular cameras, arranging them on the same great circle plane of the celestial sphere. During imaging, the control module cameras rotate around a fixed axis while capturing images at a specific frequency, obtaining a precise temporal scan image sequence without the need for dedicated reset and adjustment. The central computer processes the captured results of the precise temporal scan image sequence based on estimated scene information to obtain a full-sky image containing four-dimensional spatiotemporal information.

[0023] The imaging device of the present invention, which uses a combined modular camera for sparse sampling of the entire 4π celestial sphere through individual rotation, is based on the concept of quasi-two-dimensional continuous sampling covering four-dimensional spacetime. It effectively leverages the diverse topological combination capabilities and high-precision, low-distortion imaging performance of the novel modular camera, avoiding the error superposition caused by multi-axis rotation. The invention also includes a geometric mapping model for the optical axis pointing of the 4π celestial sphere spatial sampling, which can guide the optimal topological combination of the modular camera, thereby achieving complete and accurate 4π celestial sphere spatial imaging. Attached Figure Description

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1 This is a flowchart of the imaging device for all-sky 4π individually rotated sparse sampling using a combined module camera according to the present invention.

[0026] Figure 2 This is a schematic diagram of the near-field blind spot of the module camera involved in the embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram illustrating the calculation of near-field blind zone parameters for a module camera according to an embodiment of the present invention, wherein: Left: Schematic diagram of diagonal blind zone parameter calculation; Right: Schematic diagram of boundary blind zone parameter calculation.

[0028] Figure 4 This is a schematic diagram of a 2π-ring spatial imaging system in which modular cameras are combined on the same plane, as described in an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the module camera layout and the rotation of the 2π-ring spatial imaging system with the periodic rotating actuator, as described in the embodiment of the present invention. Detailed Implementation

[0030] The inventive concept of this invention is:

[0031] The advent of modular cameras has made it possible to construct imaging systems with the required topological structures. As is known from geometric principles, a three-dimensional image can be obtained by continuously moving a two-dimensional graphic according to certain rules; by constructing the correspondence between the movement of the two-dimensional graphic and its time series, a sparsely sampled four-dimensional spatiotemporal envelope can be further obtained. Based on this principle, this invention combines and rotates modular cameras according to specific rules, thereby achieving precise temporal sampling of all-sky images, providing strong support for the target search, on-orbit monitoring, and surrounding perception functions of remote sensing spacecraft.

[0032] The present invention relates to a combined modular camera imaging device with all-sky 4π individually rotated sparse sampling, such as... Figure 1 As shown, its hardware includes: multiple modular cameras, a periodic rotary actuator, a periodic rotary actuator controller, a wireless signal transmission device, and a central unit.

[0033] The imaging device of the present invention, which uses a combined modular camera for sparse sampling of 4π individual rotation of the entire celestial sphere, can calculate the near-range blind zone of the modular camera by selecting appropriate modular camera parameters and their combination.

[0034] The modular cameras are connected by a mechanism and can be combined in the same plane to form a 2π-ring spatial imaging system.

[0035] The 2π ring spatial imaging system is mounted on a periodic rotary actuator and has a single-axis 360° rotational degree of freedom.

[0036] The central unit calculates the operating parameters of the cycle rotation actuator controller and the module camera based on the imaging task, and sends them to the corresponding module;

[0037] The controller for the periodic rotary actuator sets the rotational speed and starting point of the periodic rotary actuator;

[0038] The modular camera rotates unidirectionally with the periodic rotating actuator, outputting a precise time-series scan image sequence;

[0039] The central computer processes the precise temporal scan image sequence based on the estimated information such as the location and distance of objects to obtain a full-sky 4π spatial image.

[0040] In the imaging device, the central unit uses a wireless signal transmission device to exchange signals with the module camera and the periodic rotary actuator controller, and the periodic rotary actuator controller and the periodic rotary actuator use a data cable to exchange signals.

[0041] Specific working principle description: According to geometric principles, a three-dimensional image can be obtained by the continuous movement of a two-dimensional graphic in a certain rule; by constructing the corresponding relationship between the movement process of the two-dimensional graphic and the time series, a sparse four-dimensional spatio-temporal envelope can be further obtained. Based on this idea, cameras with connection mechanism modules are combined in the same plane to form a 2π space imaging system, and are installed on a periodic rotation actuator, so that it has a single-axis 360° rotational freedom of movement; the central machine calculates the working parameters of the periodic rotation actuator controller and the module cameras according to the imaging task, and sends them to the corresponding modules; the periodic rotation actuator controller sets the rotation speed and starting point of the periodic rotation actuator; the module cameras rotate unidirectionally with the periodic rotation actuator, and output a precise time-sequence scanning image sequence; the central machine processes the precise time-sequence scanning image sequence based on the estimated information such as the scene azimuth and distance, so as to obtain a 4π space image of the entire celestial sphere.

[0042] The following embodiments given in conjunction with the accompanying drawings will further describe the mechanism device of the present invention in detail.

[0043] As Figure 4 shown, each module camera adopted in this embodiment is equipped with two imaging units, and four module cameras are spliced in a "field" shape.

[0044] As Figure 2 shown, in this embodiment, from the symmetry relationship of the 2π space imaging system, it can be known that by only calculating the field of view ranges of the imaging units inside the module cameras and adjacent module cameras, the relationship between the field of view range of the 2π space imaging system and the module camera parameters and installation methods can be obtained. The field of view blind areas include diagonal blind areas and boundary blind areas, which are marked with diagonal lines in the figure.

[0045] As Figure 3 shown, in this embodiment, the side length a of the module camera is 250 mm, the installation angle ε of the imaging unit is 22.5°, the distance d from the principal point of the imaging unit to the edge of the module camera is 10 mm, and the half field of view angle θ is 35°.

[0046] In this embodiment, the parameters describing the blind area range can be calculated as:

[0047]

[0048] L1 is the length of the intersection part of the center distance of the diagonal blind area and the extension line of the diagonal of the module camera, and L2 is the center distance of the boundary blind area, which is the length of the intersection part of the blind area and the extension line of the boundary of the module camera. The scene distance L should satisfy:

[0049] L≥L1^L≥L2

[0050] In this embodiment, the scene distance L>450 mm is selected to ensure no missing imaging and facilitate laboratory use.

[0051] In this embodiment, when the periodic rotation actuator drives the 2π-ring spatial imaging system to rotate around the rotation axis from ρ = 0° to ρ = 180°, full-sky imaging can be completed. During this process, the shooting position can be selected according to the target distribution. To ensure no omissions, the interval Δρ between two adjacent imaging angles should satisfy the following:

[0052] Δρ≤arccos(cos(2θ) / cos(2ε))=61°

[0053] In this embodiment, during the rotation process of the 2π ring spatial imaging system, with an interval of Δρ = 60° between two adjacent imaging angles and ρ = 0° to 180°, t0 and t2 are selected. i t j Imaging is performed three times at ρ = 0°, 60°, and 120°, which not only satisfies the requirement of complete imaging of the entire sky, but also ensures that the fine temporal scan image sequence has good spatial symmetry, making it easy for the central computer to process.

[0054] In this embodiment, after performing one full-sky imaging at ρ = 0° to 180°, another full-sky imaging can be completed by rotating ρ = 180° to 360° without the need for special resetting.

[0055] In this embodiment, as Figure 5 As shown, eight high-precision imaging units are numbered n=1 to 8 respectively. The captured images are arranged according to the imaging unit and time sequence and then sent to the central unit via a wireless signal transmission device. The central unit processes the precise time-series scan image sequence based on the estimated information such as the location and distance of objects to obtain a full-sky 4π spatial image.

[0056] It should be noted that the topology of the 2π ring spatial imaging system is not unique, depending on the module camera parameters and mission requirements. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An imaging device for 4π individual rotational sparse sampling of the entire celestial sphere using a combined modular camera, characterized in that, include: Multiple modular cameras, a periodic rotary actuator, a periodic rotary actuator controller, a wireless signal transmission device, and a central unit; Multiple modular cameras are connected by a connecting mechanism and combined on the same plane to form a ring 2π spatial imaging system; the ring 2π spatial imaging system is mounted on a periodic rotary actuator, which has a single-axis 360° rotational degree of freedom. The controller for the periodic rotary actuator is used to set the rotational speed and starting point of the periodic rotary actuator; The wireless signal transmission device is used to transmit signals between the central unit and the module camera and the controller of the periodic rotary actuator; The central unit calculates the operating parameters of the rotating actuator controller and multiple modular cameras based on the imaging task and sends them to the corresponding modules; The controller of the periodic rotary actuator is connected to the periodic rotary actuator via a data cable; signals are transmitted between the controller and the periodic rotary actuator via the data cable. The central computer processes the precise temporal scan image sequence based on the estimated location and distance of objects to obtain a full-sky 4π spatial image.

2. The imaging device for all-sky 4π individually rotated sparse sampling using a combined modular camera according to claim 1, characterized in that, In a 2π-ring spatial imaging system, the half-field angle of the imaging unit is θ, and the angle between the imaging unit and the diagonal of the modular camera is the imaging unit mounting angle ε. At this time, the angular interval Δρ between two adjacent imaging operations in the 2π-ring spatial imaging system satisfies: Δρ≤arccos(cos(2θ) / cos(2ε)).

3. The imaging device for all-sky 4π individual rotational sparse sampling using a combined modular camera according to claim 1, characterized in that, Each modular camera has two imaging units.

4. The imaging device for all-sky 4π individually rotated sparse sampling using a combined modular camera according to claim 1, characterized in that, The module camera parameters and imaging angle intervals are determined by calculating the module camera blind zone.

5. The imaging device for all-sky 4π individually rotated sparse sampling using a combined modular camera according to claim 1, characterized in that, ε is the mounting angle of the imaging unit, θ is the half-field angle, a is the side length of the module camera, and the scene distance L should satisfy: L≥L1∧L≥L2 in: L1 is the center distance of the diagonal blind zone, the length of the intersection between the blind zone and the extended diagonal line of the module camera, and L2 is the length of the intersection between the blind zone and the extended boundary line of the module camera, the center distance of the boundary blind zone.

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