Polar axis alignment method, imaging apparatus and computer program product

Abstract

The invention provides a polar axis alignment method, imaging equipment and a computer program product, and relates to the field of astronomical photography. The polar axis alignment method comprises the following steps: controlling an optical module of the imaging equipment to obtain at least two celestial body images at different azimuth angles obtained by rotating around a horizontal rotating shaft of a two-axis alignment device of the imaging equipment at a first elevation angle; determining an adjustment amount based on the at least two celestial body images and the target celestial pole position coordinates; wherein the adjustment amount is used for adjusting the two-shaft alignment device; and updating the adjustment amount based on the adjusted two-axis alignment device until the adjustment amount is within the allowable deviation range. According to the polar axis alignment method provided by the embodiment of the invention, the horizontal rotating shaft of the theodolite can be quickly pointed to the polar axis, the axis is controlled to rotate at a constant speed after the horizontal rotating shaft of the theodolite is controlled to point to the polar axis, and a shot picture is also fixed, so that long-time exposure can be realized, and the imaging quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of astronomical photography, in particular, to a polar axis alignment method, an imaging device and a computer program product. BACKGROUND

[0002] In astronomical photography, the rotation of the earth will cause the celestial coordinate system to continuously rotate relative to the camera sensor. In the fixed tripod mode, the theodolite can only rotate in the horizontal and vertical directions, and the position of the celestial body is constantly offset, resulting in star point trailing lines during long exposure. Even if the theodolite is controlled to rotate so that the optical lens group always points to a certain direction, this situation cannot be avoided.

[0003] Therefore, in the field of astronomical photography, an equatorial telescope is often used to replace the theodolite in a scene requiring long exposure, so that the equatorial telescope points to the target celestial pole (north celestial pole or south celestial pole), and the equatorial telescope rotates at a constant speed with the rotation of the celestial body, so that the image observed by the imaging device remains unchanged.

[0004] However, based on the theodolite imaging device (not including the equatorial telescope), there is still a problem of star point trailing lines when the exposure time is slightly long, and even after post-processing, the upper limit of the image quality is relatively low. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a polar axis alignment method, an imaging device and a computer program product, which quickly and accurately adjusts the horizontal rotation axis of the theodolite of an all-in-one machine, and introduces a real-time feedback mechanism during the adjustment process, thereby greatly shortening the time length of the polar axis alignment of the horizontal rotation axis of the theodolite.

[0006] In a first aspect, the embodiments of the present application provide a polar axis alignment method, which comprises: controlling an optical module of an imaging device to rotate at different azimuth angles around a horizontal rotation axis of a two-axis alignment device of the imaging device at a first altitude angle, and obtaining at least two celestial images; determining an adjustment amount based on the at least two celestial images and a target celestial pole position coordinate; wherein the adjustment amount is used to adjust the two-axis alignment device; updating the adjustment amount based on the adjusted two-axis alignment device until the adjustment amount is within an allowable deviation range.

[0007] In the above implementation process, the polar axis alignment method provided by the embodiments of the present application controls the imaging device to capture at least two celestial images at different azimuth angles of the two-axis alignment device, calculates the deviation amount of the target adjustment axis and the polar axis based on the image center coordinates, adjusts the target adjustment axis, and continuously adjusts the deviation to be within the allowable range, thereby achieving high-precision polar axis calibration. Using the polar axis calibration method provided by the embodiments of the present application can significantly improve the accuracy of celestial body tracking, ensure that the star points are not trailing lines during long exposure, and simplify the operation process, thereby providing a more efficient polar axis alignment method for astronomical photography.

[0008] Optionally, in the embodiment of the present application, the adjustment amount is updated based on the adjusted two-axis alignment device, comprising: obtaining an actual change amount of the two-axis alignment device, determining an actual pointing coordinate of the horizontal rotation axis of the two-axis alignment device; determining a deviation amount between the current horizontal rotation axis and the target celestial pole based on the actual pointing coordinate and the target celestial pole coordinate; and updating the adjustment amount according to the deviation amount.

[0009] In the above implementation process, the polar axis alignment method provided by the embodiment of the present application can obtain an actual change amount of the two-axis alignment device based on the capture of the physical motion of the mechanical axis of the two-axis alignment device after adjusting the two-axis alignment device through two-diagram analysis or three-diagram analysis; and update the adjustment amount according to the deviation amount between the current horizontal rotation axis and the target celestial pole; thereby quickly updating the adjustment amount, greatly shortening the length of adjustment-feedback-readjustment, and greatly improving the efficiency of polar axis alignment.

[0010] Optionally, in the embodiment of the present application, the actual change amount of the two-axis alignment device is obtained based on a gyroscope; and in the case that the adjustment amount is within the deviation allowable range, the current position is taken as the zero position of the gyroscope.

[0011] In the above implementation process, the polar axis alignment method provided by the embodiment of the present application can monitor the physical motion of the two-axis alignment device in real time through the gyroscope, dynamically lock the zero position of the gyroscope within the deviation allowable range, and dynamically correct the zero position of the gyroscope through real-time motion data, so as to adapt to the zero drift caused by mechanical wear or environmental disturbance.

[0012] Optionally, in the embodiment of the present application, the adjustment amount is updated based on the adjusted two-axis alignment device, comprising: changing the azimuth angle of the optical module again, and obtaining an astronomical image; determining a deviation amount between the current horizontal rotation axis and the target celestial pole based on the last two astronomical images and the target celestial pole coordinate; and updating the adjustment amount according to the deviation amount.

[0013] In the above implementation process, the polar axis alignment method provided by the embodiment of the present application can obtain a new astronomical image again after adjusting the two-axis alignment device through two-diagram analysis or three-diagram analysis, and perform two-diagram analysis or three-diagram analysis again. First, two star maps (N1-N3) at different azimuth angles are photographed at the initial position, the initial polar axis deviation is calculated through fitting star point coordinates (astronomical coordinates), and the first correction is performed; then, two verification star maps (N2-N4) are photographed again at the adjusted position, the residual error is analyzed again based on the displacement of the new star points, and the pointing coordinate of the selected rotation axis is gradually approximated to the target celestial pole through iterative optimization. This method improves the polar axis alignment accuracy through continuous geometric constraints, and finally matches the physical motion trajectory of the mechanical axis with the rotation of the celestial sphere, so as to realize polar axis alignment.

[0014] Optionally, in the embodiment of the present application, after the adjustment amount is updated based on the two-axis alignment device after adjustment, the method further comprises: controlling the optical module of the imaging device to rotate at the different azimuth angles obtained by the optical module of the imaging device around the horizontal rotation axis of the two-axis alignment device at the second elevation angle to obtain at least two celestial images; determining the deviation between the horizontal rotation axis of the two-axis alignment device after adjustment and the target celestial pole based on the at least two celestial images and the target celestial pole position coordinates; and determining whether the adjustment amount is within the deviation allowable range according to the deviation.

[0015] In the above implementation process, the polar axis alignment method provided in the embodiment of the present application can determine whether the current adjustment amount is within the deviation allowable range in time after the horizontal rotation axis of the two-axis alignment device is adjusted twice, and can avoid repeated correction of the user in a small error range while considering the deviation accumulation of the two adjustments.

[0016] Optionally, in the embodiment of the present application, after the adjustment amount is updated based on the two-axis alignment device after adjustment until the adjustment amount is within the deviation allowable range, the method further comprises: monitoring the two-axis alignment device change information, and determining whether the imaging device has a severe pose change according to the two-axis alignment device change information; and generating a positioning mode replacement prompt information in a case where it is determined that the imaging device has a severe pose change.

[0017] In the above implementation process, the polar axis alignment method provided in the embodiment of the present application can quickly and accurately identify the severe displacement or vibration of the imaging device by monitoring the pose change information of the two-axis alignment device in real time, and can generate a positioning mode replacement prompt immediately after determining the abnormality. Thus, the polar axis misalignment problem caused by sudden interference in astronomical photography can be responded in time, and the invalid exposure can be greatly avoided through the early warning or alarm mechanism.

[0018] Optionally, in the embodiment of the present application, before the at least two celestial images are obtained by controlling the optical module of the imaging device to rotate at the different azimuth angles obtained by the optical module of the imaging device around the horizontal rotation axis of the two-axis alignment device at the first elevation angle, the method further comprises: generating initial orientation adjustment information of the imaging device according to the target celestial pole position; and generating the first elevation angle according to the position coordinates of the imaging device.

[0019] In the above implementation process, in the polar axis alignment method provided in the embodiment of the present application, the general orientation of the device needs to be adjusted first, which is beneficial to efficiently and accurately align the horizontal rotation axis of the two-axis alignment device to the polar axis later.

[0020] In a second aspect, an embodiment of the present application provides an imaging device, the imaging device comprising a two-axis alignment device, an optical module, and a control module; the two-axis alignment device is configured to determine a pointing position of the optical module; the optical module is configured to obtain at least two celestial images at different azimuth angles of a target altitude angle of a horizontal rotation axis of the two-axis alignment device; the control module is configured to determine an adjustment amount based on the at least two celestial images and a target celestial pole position coordinate; wherein the adjustment amount is used to adjust the two-axis alignment device; and the control module is further configured to update the adjustment amount based on the adjusted two-axis alignment device.

[0021] Optionally, in an embodiment of the present application, the imaging device further comprises a gyroscope; and during the process of updating the adjustment amount based on the adjusted two-axis alignment device, the control module is specifically configured to: determine an actual pointing coordinate of the horizontal rotation axis of the adjusted two-axis alignment device according to an actual change amount of the two-axis alignment device monitored by the gyroscope; determine a deviation amount between the current horizontal rotation axis and the target celestial pole based on the actual pointing coordinate and the target celestial pole position coordinate; and update the adjustment amount according to the deviation amount.

[0022] Optionally, in an embodiment of the present application, the imaging device further comprises a support module of an altitude angle indicating mechanism and an azimuth angle indicating mechanism; and the two-axis alignment device is fixed to the support module; the altitude angle indicating mechanism is configured to display an altitude angle indication of the optical module; and the azimuth angle indicating mechanism is configured to display an azimuth angle indication of the optical module.

[0023] In a third aspect, an embodiment of the present application provides a computer program product, the computer program product comprising computer programs / instructions, which are executed by a processor to perform the steps in any implementation manner of the first aspect.

[0024] In a fourth aspect, an embodiment of the present application provides an electronic device, the electronic device comprising a memory and a processor; the memory stores program instructions; and the processor reads and runs the program instructions to perform the steps in any implementation manner of the first aspect.

[0025] In a fifth aspect, an embodiment of the present application further provides a computer readable storage medium, the readable storage medium storing computer program instructions; and the computer program instructions are read and run by a processor to perform the steps in any implementation manner of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 A flowchart of polar axis alignment provided for an embodiment of the present application; Figure 2 A first flowchart of adjustment amount updating provided for an embodiment of the present application; Figure 3 A second flowchart of adjustment amount updating provided for an embodiment of the present application; Figure 4 A step flowchart of whether the adjustment amount is within the deviation allowable range provided for an embodiment of the present application; Figure 5 An initial pose adjustment flowchart provided for an embodiment of the present application; Figure 6 A module schematic diagram of an imaging device provided for an embodiment of the present application; Figure 7 A structural schematic diagram of an electronic device provided for an embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described below with reference to the drawings of the embodiments of the present application. For example, the flowcharts and block diagrams in the drawings show the possible implementation architectures, functions and operations of the systems, methods and computer program products according to the embodiments of the present application. In this regard, each block in the flowcharts or block diagrams can represent a module, a program segment or a part of code, which contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur in different orders from those noted in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and sometimes they can be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and the combination of blocks in the block diagrams and / or flowcharts, can be implemented by a dedicated hardware-based system that performs the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions. In addition, the functional modules in the various embodiments of the present application can be integrated together to form a separate part, or each module can exist independently, or two or more modules can be integrated to form a separate part.

[0029] For the existing astronomical photography all-in-one machine, it is generally a combination of the theodolite and optical components. Since the celestial bodies rotate around the polar axis with time, the theodolite can only rotate in the horizontal and vertical directions, which is a translation relative to the celestial sphere, and does not allow the rotation axis of the astronomical photography all-in-one machine to move synchronously with the polar axis.

[0030] The inventor has found that in this process, when the single exposure time is slightly longer, serious star streaks are generated, resulting in insufficient single frame signal-to-noise ratio; due to the inability to perform long exposure, even if the quality is improved through multi-frame superposition, complex rotation alignment processing is still required, and due to the rotation of the sensor, the quality of the center and the edge after superposition is uneven, and the overall signal-to-noise ratio is still inferior to long exposure. In addition, the fixed viewing angle limits the composition diversity, and if the viewing angle is expanded through splicing, the efficiency is extremely low.

[0031] Based on this, the present application provides an extreme axis alignment method, an imaging device and a computer program product. The extreme axis alignment method is applied to an all-in-one machine including a theodolite, which can quickly point the horizontal rotation axis of the theodolite to the polar axis, control the horizontal rotation axis of the theodolite to point to the polar axis, and then control the axis to rotate at a constant speed. The captured image is also fixed, so that long-time exposure can be realized, and the imaging quality is improved.

[0032] Please refer to Figure 1 , Figure 1 The flowchart of the extreme axis alignment provided by the embodiment of the present application; the present application provides an extreme axis alignment method, which can be executed by Figure 6 the imaging device.

[0033] The extreme axis alignment method includes the following steps: Step S100: control the optical module of the imaging device to rotate around the horizontal rotation axis of the two-axis alignment device of the imaging device at different azimuth angles under the first elevation angle to obtain at least two celestial images.

[0034] If two celestial images are obtained, in the above step S100, the two celestial images obtained are obtained at different azimuth angles under the first elevation angle.

[0035] If three celestial images are obtained, in the above step S100, the three celestial images obtained are obtained at different azimuth angles under the first elevation angle.

[0036] Among them, the position of the first elevation angle is generally a moderate position without being too close to the zenith and the horizon, to ensure that the horizontal rotation axis is roughly aligned with the target celestial pole. In the embodiment of the present application, the target celestial pole refers to the north celestial pole or the south celestial pole.

[0037] Exemplarily, taking the acquisition of two celestial images as an example, the first azimuth angle position of the horizontal rotation axis is used to capture the first celestial image, and the image center coordinates M1(x1, y1) are recorded. Keep the elevation angle unchanged, rotate the horizontal rotation axis to the second azimuth angle position, realign the same star and capture the second celestial image, and record the image center coordinates M2(x2, y2).

[0038] Exemplarily, taking acquiring three celestial images as an example, a first celestial image is photographed at a first azimuth position of the horizontal rotation axis, and the image center coordinates N1 (x1, y1) are recorded; a second celestial image is photographed at a second azimuth position of the horizontal rotation axis by keeping the altitude angle unchanged, and the image center coordinates N2 (x2, y2) are recorded; a third celestial image is photographed at a third azimuth position of the horizontal rotation axis by keeping the altitude angle unchanged, and the image center coordinates N3 (x3, y3) are recorded.

[0039] The two-axis alignment device, in the embodiment of the present application, refers to an alignment device including a horizontal rotation axis and a vertical rotation axis. By controlling one of the axes to align with the celestial north pole and controlling the axis to rotate at a uniform speed together with the polar axis, the deviation of the celestial visual motion caused by the earth rotation is compensated, the polar axis calibration is realized, and the star point is ensured not to be dragged when long-time exposure.

[0040] The two-axis alignment device may be a theodolite or an equatorial telescope. In the case where the two-axis alignment device provided in the embodiment of the present application is a theodolite, the horizontal rotation axis of the theodolite is adjusted in the process of polar axis alignment. In the case where the two-axis alignment device provided in the embodiment of the present application is an equatorial telescope, the right ascension axis of the equatorial telescope is adjusted in the process of polar axis alignment.

[0041] Step S200: determining an adjustment amount based on the at least two celestial images and the target celestial pole position coordinates. The adjustment amount is used to adjust the two-axis alignment device.

[0042] In the above step S200, the adjustment amount for adjusting the two-axis alignment device is determined based on the at least two celestial images and the target celestial pole position coordinates. According to the three celestial images or the two celestial images obtained in the above step S100, the deviation between the target adjustment axis of the two-axis alignment device to be aligned with the target celestial pole and the polar axis is calculated, and the adjustment amount for adjusting the target adjustment axis of the two-axis alignment device is determined.

[0043] After the imaging device photographs a celestial image, a.wcs file is generated. This file maps the pixel position to the celestial coordinate system through a spatial transformation model, and can realize bidirectional conversion between any position in the image (including the extended area outside the picture) and the astronomical coordinates. This conversion is based on image analysis data, and the coordinate conversion of the central area of the picture is very accurate, but as the position deviates from the image center, the error of the conversion result will gradually increase. Therefore, in the embodiment of the present application, the image center coordinates are used as the basic data for analysis.

[0044] Optionally, the following is an implementation process for solving the coordinates (x, y) of the rotation center P by using two photos A and B taken near the target celestial pole and the corresponding WCS files A.wcs and B.wcs: Since P is the objective rotation center, its celestial coordinates in the two photos, (ra, dec) and (ra', dec'), obtained through WCS conversion, should theoretically be consistent. If they are not consistent, it means that the initial assumption of (x, y) is inaccurate, and an iterative approximation algorithm (such as adjusting the value of x or y) is needed to minimize the deviation of (ra, dec) and (ra', dec') until the preset tolerance threshold is met. The final (x, y) is the real coordinate of the rotation center P, and subsequent deviation analysis and correction can be based on the difference between this coordinate and the actual coordinate of the target celestial pole.

[0045] Alternatively, there is another method to obtain the polar axis of the two celestial images, which has a similar operation process as before, but the specific implementation is different. Using a wide-angle lens, two images with adjacent and partially overlapping regions are taken, and the rotation relationship between the two images is determined by aligning the common stars in the overlapping region, and the coordinates of the rotation center are calculated.

[0046] It should be noted that this method requires that there be enough common stars between the images and the rotation amplitude cannot be too small, so a wide-angle lens is required to ensure sufficient field of view overlap and star matching conditions.

[0047] Alternatively, based on three celestial images, one implementation of the polar axis is as follows: by taking three images, aligning and matching the overlapping stars between the second and third images and the first image, and combining the coordinate transformation relationship of the first image to calculate the center coordinates of the other two images, the rotation center position is finally calculated based on the planar geometric relationship of the three center coordinates. In this process, only a single WCS analysis is required, but it needs to ensure sufficient overlapping star matching accuracy between images, and the polar axis calibration is achieved by replacing multiple analyses with geometric derivation.

[0048] In the embodiments of the present application, the adjustment amount is generated based on the deviation amount, and finally displayed on the user end is how much to move up, down, left and right. Of course, this display can be combined with the actual support structure form, for example, the support structure is provided with a height scale, which can be used to display how many degrees the height needs to be adjusted, and the support structure is provided with a horizontal rotation scale, which can be used to display how many degrees to turn in which direction.

[0049] Step S300: Update the adjustment amount based on the adjusted two-axis alignment device until the adjustment amount is within the allowable deviation range.

[0050] In step S300, the position of the target adjustment axis is fine-tuned by the adjustment amount in step S200, so that the pointing coordinate of the target adjustment axis changes; for the two-axis alignment device after adjustment, it is necessary to confirm again whether the target adjustment axis is aligned with the polar axis; if not, the deviation amount is updated according to the existing deviation amount, and the target rotation axis is adjusted again based on the updated deviation amount until the target adjustment axis is aligned with the polar axis, or the deviation between the target adjustment axis and the polar axis is within the allowed deviation range.

[0051] In the above implementation process, the allowed deviation range can be set according to the accuracy requirement of the imaging device. For deep space photography, for example, the allowed deviation range is less than 5 angular minutes.

[0052] By Figure 1 It can be seen that the polar axis alignment method provided in the embodiments of the present application controls the imaging device to shoot at least two celestial images at different azimuth angles of the two-axis alignment device, calculates the deviation amount of the target adjustment axis from the polar axis based on the image center coordinates, and then adjusts the target adjustment axis, and continuously adjusts the target adjustment axis to reduce the deviation to within the allowed range, thereby achieving high-precision polar axis calibration. Using the polar axis calibration method provided in the embodiments of the present application can significantly improve the accuracy of celestial tracking, ensure that the star points do not drag lines during long-time exposure, and at the same time simplify the operation process, providing a more efficient polar axis alignment method for astronomical photography.

[0053] Please refer to Figure 2 , Figure 2 The first flowchart of the adjustment amount updating provided in the embodiments of the present application; in the optional implementation manner of the embodiments of the present application, the updating of the adjustment amount based on the adjusted two-axis alignment device in step S300 can be realized by the following steps: Step S311: obtaining the actual change amount of the two-axis alignment device, and determining the actual pointing coordinate of the horizontal rotation axis of the two-axis alignment device.

[0054] In step S311, the actual change amount of the two-axis alignment device is obtained, that is, the physical movement of the mechanical axis is captured in real time, and the actual pointing coordinate of the horizontal rotation axis of the two-axis alignment device during adjustment and after adjustment is determined. In the above implementation process, the actual change amount of the two-axis alignment device can be obtained in real time by a motion sensor (such as a MU inertial measurement unit), a direction sensor (such as an electronic compass / magnetometer), and / or an acceleration sensor (such as an inclinometer).

[0055] Step S312: determining the deviation amount between the current horizontal rotation axis and the target celestial pole based on the actual pointing coordinate and the target celestial position coordinate.

[0056] In step S312, the actual pointing coordinates obtained in step S311 are compared with the target polar coordinates, and the deviation of the current horizontal rotation axis is calculated. For example, if the actual pointing coordinates deviate from the target polar position, the deviation (e.g., azimuth angle deviation Δα and elevation angle deviation Δβ) between the two can be determined to ensure that the deviation truly reflects the polar axis alignment error.

[0057] Step S313: updating the adjustment amount according to the deviation.

[0058] In step S313, the adjustment amount is dynamically updated based on the deviation in step S312. In actual application, the updated adjustment amount can be sent to the client, and the user manually adjusts the horizontal rotation axis of the two-axis alignment device based on the updated adjustment amount.

[0059] Optionally, for the updated adjustment amount, a correction instruction can be generated by a PID control or an iterative algorithm to drive the motor to fine-tune the horizontal rotation axis.

[0060] By Figure 2 It can be seen that the polar axis alignment method provided in the embodiments of the present application can obtain the actual change amount of the two-axis alignment device based on the capture of the physical movement of the mechanical axis of the two-axis alignment device after adjusting the two-axis alignment device by the three-graph analysis method; and then update the adjustment amount according to the deviation between the current horizontal rotation axis and the target polar axis. The adjustment amount can be quickly updated, the time length of adjustment-feedback-readjustment is greatly shortened, and the efficiency of polar axis alignment is greatly improved.

[0061] In an optional embodiment, the actual change amount of the two-axis alignment device is obtained based on a gyroscope.

[0062] In the case where the adjustment amount is within the deviation allowable range, the current position is taken as the zero position of the gyroscope.

[0063] In the embodiments of the present application, the actual change amount of the two-axis alignment device can be obtained based on a gyroscope. The gyroscope is a sensor for measuring or maintaining angular velocity or direction. In the embodiments of the present application, the gyroscope detects the physical change amount of the azimuth angle and the elevation angle of the horizontal rotation axis of the two-axis alignment device.

[0064] When the user considers the polar axis alignment (the adjustment amount is within the deviation allowable range or the adjustment amount is 0), the current position is taken as the zero position of the gyroscope.

[0065] Optionally, in the case where the adjustment amount is within the deviation allowable range, the current position is taken as the zero position of the gyroscope, and after forced zero position refreshing (or prompting the gyroscope zero position refreshing), the shooting mode can be entered.

[0066] Therefore, the polar axis alignment method provided by the embodiment of the application can monitor the physical movement of the two-axis alignment device in real time through the gyroscope, dynamically lock the gyroscope zero within the deviation allowable range, dynamically correct the gyroscope zero through real-time movement data, and adapt to the zero drift caused by mechanical wear or environmental disturbance.

[0067] Based on the introduction of the gyroscope, the polar axis alignment method provided by the embodiment of the application can realize accurate and efficient alignment of the polar axis through a simpler way through real-time feedback mechanism in the process of polar axis alignment, greatly reduce the probability of invalid operation caused by increased deviation after adjustment, and reduce negative feedback. The angle between the sensor (rectangle) in the equatorial mode and the photographed celestial body is always consistent, and they rotate around the polar axis at the same speed, so each image can be effectively superimposed with the maximum amplitude. In the image processing method, the step of rotating the image is omitted, which reduces the computational burden to a certain extent, but more importantly, improves the image quality.

[0068] Please refer to Figure 3 , Figure 3 The second flowchart for updating the adjustment amount is provided for the embodiment of the application. In the optional embodiment of the embodiment of the application, the updating of the adjustment amount based on the adjusted two-axis alignment device in the step S300 can be realized through the following steps. Step S321: Change the azimuth angle of the optical module again, and obtain a celestial image.

[0069] In the above step S321, similarly, the optical module of the imaging device is controlled to rotate around the horizontal rotation axis of the two-axis alignment device of the imaging device at the current altitude angle (after the first adjustment), the azimuth angle is changed, and a celestial image is obtained again.

[0070] Step S322: Based on the latest three celestial images and the target celestial pole position coordinates, determine the deviation amount between the current horizontal rotation axis and the target celestial pole.

[0071] In the above step S322, based on the star point coordinates of the latest three celestial images and the target celestial pole theoretical position, the real-time deviation amount of the horizontal rotation axis is recalculated; by fitting the star point displacement trajectory (such as a circular arc or a linear deviation), the residual error component of the azimuth angle and the altitude angle, i.e., the deviation amount between the current horizontal rotation axis and the target celestial pole, can be separated out.

[0072] Step S323: Update the adjustment amount according to the deviation amount.

[0073] In the above step S323, the adjustment amount is dynamically updated based on the deviation amount of step S322. In actual application, the updated adjustment amount can be sent to the client, and the user can manually adjust the horizontal rotation axis of the two-axis alignment device based on the updated adjustment amount.

[0074] Optionally, for the updated adjustment amount, a correction instruction can be generated by PID control or an iterative algorithm to drive the motor to fine-tune the horizontal rotation shaft.

[0075] Taking three image analysis as an example, two implementation modes of the updated adjustment amount are illustrated: Illustratively, after obtaining three celestial images in the above step S100, the center coordinates of the three celestial images are N1(x1, y1), (x2, y2) and N3(x3, y3), after the initial adjustment of the two-axis alignment device, a celestial image is obtained again based on the adjusted imaging device, and the center point coordinate is N4(x4, y4), assuming that the target celestial pole theoretical position is (a0, d0). According to (x2, y2), N3(x3, y3) and N4(x4, y4), the pointing coordinates of the current horizontal rotation shaft are calculated, assuming that they become (a1, d1), then the azimuth deviation amount is Da = a1-a0, and the altitude angle deviation amount is Dd = d1-d0. Take Da and Dd as the updated adjustment amount, prompt the user the degree of azimuth angle that should be adjusted in a certain direction, and the degree of altitude angle that should be adjusted in a certain direction.

[0076] Illustratively, after obtaining three celestial images in the above step S100, the center coordinates of the three celestial images are N1(x1, y1), (x2, y2) and N3(x3, y3), after the initial adjustment of the two-axis alignment device, three celestial images are obtained again based on the adjusted imaging device, and the center point coordinates are N4(x4, y4), N5(x5, y5) and N6(x6, y6), assuming that the target celestial pole theoretical position is (a0, d0). According to N4(x4, y4), N5(x5, y5) and N6(x6, y6), the pointing coordinates of the current horizontal rotation shaft are calculated, assuming that they become (a1, d1), then the azimuth deviation amount is Da = a1-a0, and the altitude angle deviation amount is Dd = d1-d0. Take Da and Dd as the updated adjustment amount, prompt the user the degree of azimuth angle that should be adjusted in a certain direction, and the degree of altitude angle that should be adjusted in a certain direction.

[0077] By Figure 3It can be known that the polar axis alignment method provided in the embodiment of the application can obtain new celestial images again after adjusting the two-axis alignment device through the three-image analysis method, and then perform three-image analysis again. Firstly, three star images (N1-N3) at different azimuth angles are photographed at the initial position, the initial polar axis deviation is calculated through fitting star point coordinates (celestial coordinates), and the first correction is performed; then, three verification star images (N2-N4) are photographed again at the adjusted position, the residual error is analyzed again based on the new star point displacement, and the pointing coordinates of the selected rotation axis are gradually approximated to the target celestial pole through iterative optimization. The method improves the polar axis alignment accuracy through continuous geometric constraints, finally matches the physical motion trajectory of the mechanical axis with the rotation of the celestial sphere, and realizes the polar axis alignment.

[0078] Please refer to Figure 4 , Figure 4 The step flow chart for judging whether the adjustment amount is within the deviation allowable range is provided in the embodiment of the application. In the optional implementation manner of the embodiment of the application, after the adjustment amount is updated based on the adjusted two-axis alignment device in the step S300, the error is fed back to the user in real time after the adjustment of the two-axis alignment device, and the user can adjust the error to 0 or within the allowable range. However, the error generated in the two adjustment processes cannot be ignored after being accumulated, because the result of the first three-image analysis may have an error, and the update of the deviation amount in the second time may also have an error.

[0079] Therefore, the polar axis alignment method provided in the embodiment of the application further includes the following judgment method for whether the updated adjustment amount is within the deviation allowable range, including the following steps. Step S400: controlling the optical module of the imaging device to rotate around the horizontal rotation axis of the two-axis alignment device of the imaging device at a second elevation angle to obtain at least three celestial images at different azimuth angles.

[0080] In the step S400, the optical module of the imaging device is controlled to rotate around the horizontal rotation axis of the two-axis alignment device of the imaging device at a second elevation angle at least twice, and at least three celestial images are obtained again.

[0081] It should be noted that the first elevation angle and the second elevation angle in the above implementation process can be the same or different elevation angles, and generally are different angles from the first elevation angle.

[0082] Step S500: determining the deviation amount between the horizontal rotation axis of the adjusted two-axis alignment device and the target celestial pole based on the at least three celestial images and the target celestial pole position coordinates.

[0083] Step S600: judging whether the adjustment amount is within the deviation allowable range according to the deviation amount.

[0084] In the steps S500 to S600, based on the three celestial images obtained in the step S400, the deviation between the pointing coordinate of the horizontal rotation axis of the two-axis alignment device and the target celestial pole position is calculated according to the center coordinates of the three celestial images, and whether the adjustment amount is within the deviation allowable range is determined according to the deviation amount, so as to prompt the user whether the adjustment needs to be continued.

[0085] Thus, in the polar axis alignment method provided in the embodiments of the present application, after the horizontal rotation axis of the two-axis alignment device is adjusted twice (i.e., the adjustment is implemented by obtaining the adjustment amount based on the three-image analysis in the first time, and the adjustment is implemented by obtaining the adjustment amount based on the actual change amount of the two-axis alignment device in the second time; or, the adjustment is implemented by obtaining the adjustment amount based on the three-image analysis in the first time and the second time), the three-image analysis is performed again, which can avoid that after the adjustment, the user does not know that the rotation axis of the two-axis alignment device has been aligned with the polar axis, thereby causing the user to repeatedly correct in a small range, and it is difficult to align the polar axis.

[0086] By Figure 4 It can be known that the polar axis alignment method provided in the embodiments of the present application can timely determine whether the current adjustment amount is within the deviation allowable range after the horizontal rotation axis of the two-axis alignment device is adjusted twice, and can consider the deviation accumulation of the two adjustments, and also avoid that the user repeatedly corrects in a small error interval.

[0087] In an optional embodiment, the polar axis alignment method provided in the embodiments of the present application further includes: Monitoring the two-axis alignment device change information, and determining whether the imaging device has a dramatic pose change according to the two-axis alignment device change information.

[0088] In the case that it is determined that the imaging device has a dramatic pose change, generating alignment mode replacement prompt information.

[0089] In the embodiments of the present application, the dramatic pose change refers to that the imaging device may have a large amplitude of movement or vibration. For example, the tripod is collided to cause the whole imaging device to deviate (such as the horizontal rotation axis azimuth mutation > 5°), or the device base is shaken by strong wind, which is regarded as a dramatic change. For example, the mechanical vibration (acceleration > 0.5g) caused by the accidental touch of the lens barrel during the manual operation is also regarded as a dramatic change.

[0090] Optionally, the dramatic pose change is comprehensively determined by detecting the sudden increase of the angular velocity (such as > 10° / s) through the gyroscope or capturing the abnormal vibration (such as the frequency > 10Hz) through the acceleration sensor, and combining the displacement threshold (such as the cumulative deviation > 2° within 5 seconds) of the two-axis encoder.

[0091] The alignment mode changing prompt information is to prompt the user that the current equatorial mount mode is no longer applicable, to suggest the user to stop using the equatorial mount mode for shooting, or to suggest the user to use the altazimuth mount mode for shooting.

[0092] In some embodiments, the celestial body images are continuously monitored during shooting, and when the continuous multiple images are seriously dragged, the alignment mode changing prompt information is also generated.

[0093] Optionally, the user can be prompted by a sound signal and / or a warning, and at the same time, the equatorial mount mode can be automatically changed to the altazimuth mount mode.

[0094] Optionally, after the alignment mode changing prompt information is generated, the steps S100 to S600 provided in the embodiments of the present application can be re-executed to re-implement the polar axis alignment, the shooting plan can be re-executed after the polar axis alignment is re-completed, or the uncompleted shooting plan can be continuously executed.

[0095] Optionally, after the shooting plan is set, due to a long shooting period, errors can be accumulated, and the polar axis operation provided in the embodiments of the present application can be automatically re-executed after each target is shot.

[0096] Therefore, the polar axis alignment method provided in the embodiments of the present application can quickly and accurately identify the violent displacement or vibration of the imaging device by monitoring the pose change information of the two-axis alignment device in real time, and can immediately generate an alignment mode changing prompt after determining the abnormality. Thus, the polar axis misalignment problem caused by sudden interference in astronomical photography can be responded in time, and the invalid exposure can be greatly avoided through the early warning or warning mechanism.

[0097] Please refer to Figure 5 , Figure 5 the initial pose adjustment flowchart provided in the embodiments of the present application; in the optional implementation manner of the embodiments of the present application, before the step S100 in which the optical module of the imaging device is controlled to rotate at different azimuth angles under the first altitude angle around the horizontal rotation axis of the two-axis alignment device to obtain at least three celestial body images, the polar axis alignment method provided in the embodiments of the present application further includes the following steps: Step S1: generating initial orientation adjustment information of the imaging device according to the target celestial pole position; Step S2: generating a first altitude angle according to the position coordinates of the imaging device.

[0098] In the steps S1-S2, first, initial orientation adjustment information of the imaging device is generated according to the target celestial pole position, that is, the orientation of the imaging device needs to be adjusted to the target celestial pole position. In the initial orientation, according to the position coordinates of the imaging device, mainly relying on the latitude of the current geographic position, a first height angle to which the optical module of the imaging device needs to be adjusted is generated, for guiding the user or controlling the motor to adjust the height angle of the optical module to the first height angle.

[0099] By Figure 5 It can be known that, in the polar axis alignment method provided in the embodiment of the present application, the general orientation of the device needs to be adjusted first, which is beneficial to efficiently and accurately align the horizontal rotation axis of the two-axis alignment device with the polar axis later.

[0100] Please refer to Figure 6 , Figure 6 The module schematic diagram of the imaging device provided in the embodiment of the present application; the imaging device provided in the embodiment of the present application includes a two-axis alignment device 110, an optical module 120 and a control module 130.

[0101] The two-axis alignment device 110 is used to determine the pointing position of the optical module.

[0102] The optical module 120 is used to obtain at least three celestial images under different azimuth angles of the horizontal rotation axis of the two-axis alignment device at the target height angle.

[0103] The control module 130 is used to determine an adjustment amount based on the at least three celestial images and the target celestial pole position coordinates, wherein the adjustment amount is used to adjust the two-axis alignment device.

[0104] The control module 130 is also used to update the adjustment amount based on the adjusted two-axis alignment device.

[0105] In an optional embodiment, the imaging device 100 further includes a gyroscope; in the process of updating the adjustment amount based on the adjusted two-axis alignment device, the control module 130 is specifically used to: determine actual pointing coordinates of the horizontal rotation axis of the adjusted two-axis alignment device according to actual change amount of the two-axis alignment device monitored by the gyroscope; determine deviation amount between the current horizontal rotation axis and the target celestial pole based on the actual pointing coordinates and the target celestial pole position coordinates; and update the adjustment amount according to the deviation amount.

[0106] In an optional embodiment, in the process of updating the adjustment amount based on the adjusted two-axis alignment device, the control module 130 is specifically used to: change the azimuth angle of the optical module again and obtain a celestial image; determine deviation amount between the current horizontal rotation axis and the target celestial pole based on the last three celestial images and the target celestial pole position coordinates; and update the adjustment amount according to the deviation amount.

[0107] In an optional embodiment, the imaging device 100 is further configured to, after updating the adjustment amount based on the adjusted two-axis alignment device, control the optical module of the imaging device to capture at least three celestial images at different azimuth angles obtained by rotating the optical module of the imaging device at the second elevation angle around the horizontal rotation axis of the two-axis alignment device; determine a deviation amount between the horizontal rotation axis of the adjusted two-axis alignment device and the target celestial pole based on the at least three celestial images and the target celestial pole position coordinate; and determine whether the adjustment amount is within the deviation allowable range according to the deviation amount.

[0108] In an optional embodiment, the imaging device 100 is further configured to, after updating the adjustment amount based on the adjusted two-axis alignment device until the adjustment amount is within the deviation allowable range, monitor the two-axis alignment device change information, and determine whether the imaging device has a dramatic change in position and orientation according to the two-axis alignment device change information; and generate an alignment mode change prompt information in a case where it is determined that the imaging device has a dramatic change in position and orientation.

[0109] In an optional embodiment, the imaging device 100 is further configured to, before controlling the optical module of the imaging device to capture at least three celestial images at different azimuth angles obtained by rotating the optical module of the imaging device at the first elevation angle around the horizontal rotation axis of the two-axis alignment device, generate initial orientation adjustment information of the imaging device according to the target celestial pole position; and generate the first elevation angle according to the position coordinate of the imaging device.

[0110] In an optional embodiment, the imaging device 100 further comprises a support module of an elevation angle display mechanism and an azimuth angle display mechanism.

[0111] The two-axis alignment device is fixed to the support module. The elevation angle display mechanism is configured to display the elevation angle indication of the optical module, and the azimuth angle display mechanism is configured to display the azimuth angle indication of the optical module.

[0112] The elevation angle display mechanism can display how many degrees of elevation adjustment is needed and in which direction to turn, and the azimuth angle display mechanism can display the scale of horizontal rotation needed and in which direction to turn. When the elevation angle display mechanism and the azimuth angle display mechanism display specific adjustment amounts, it is convenient for the user to directly adjust according to the indications, and the user experience can be improved.

[0113] The elevation angle display mechanism can also display the current elevation angle indication, and the azimuth angle display mechanism can also display the current azimuth angle indication.

[0114] In the embodiments of the present application, the imaging device 100 is an all-in-one machine, and at least comprises a support module, a theodolite, and an optical module with a sensor. The movement of the support module can make the horizontal rotation axis of the theodolite point to the polar axis, and the support module is usually installed at the interface reserved below the horizontal rotation axis of the theodolite.

[0115] Optionally, the support module can be a wedge structure, the wedge including a fixed surface, an adjusting surface and a horizontal rotation surface, the angle between the fixed surface and the adjusting surface being adjustable; by fine-tuning the angle between the fixed surface and the adjusting surface, the height angle adjustment of the horizontal rotation axis of the theodolite can be realized; by rotating the horizontal rotation surface, the azimuth adjustment of the horizontal rotation axis can be realized.

[0116] Optionally, the support module can be a ball table, a camera holder or other mechanical structure capable of controlling and adjusting the direction of the horizontal rotation axis of the theodolite, and finally capable of aligning the polar axis.

[0117] No matter what kind of support module is, a number display mechanism capable of displaying the height angle and the azimuth is arranged, so that the user can directly obtain the specific position of the horizontal rotation axis of the theodolite from the device, and the user experience can be improved.

[0118] Please refer to Figure 7 , Figure 7 A structure schematic diagram of an electronic device provided by the embodiment of the present application. The electronic device 200 provided by the embodiment of the present application includes a processor 201 and a memory 202, the memory 202 stores machine readable instructions executable by the processor 201, and the machine readable instructions are executed by the processor 201 to perform the polar axis alignment method as above.

[0119] Based on the same inventive concept, the embodiment of the present application further provides a computer program product, which includes computer programs / instructions, and the computer programs / instructions are executed by a processor to realize the steps in any of the implementation manners of the polar axis alignment method.

[0120] Based on the same inventive concept, the embodiment of the present application further provides a computer readable storage medium, which stores computer program instructions, and the computer program instructions are read and run by a processor to perform the steps in any of the implementation manners of the polar axis alignment method.

[0121] The computer readable storage medium can be a random access memory (RAM), a read only memory (ROM), a programmable read only memory (PROM), an erasable programmable read only memory (EPROM), an electric erasable programmable read only memory (EEPROM) and various media capable of storing program codes.

[0122] In this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0123] The embodiments of the present application described hereinabove are implemented in software, firmware, hardware, or a combination of them. The elements and acts of the embodiments described herein can be combined, divided, re-ordered, omitted, or supplemented, other elements and acts can be added, or some of the elements and acts can be improved, without departing from the scope of the present application. It is therefore apparent that the particular embodiments of the present application are provided for purposes of illustration and not for purposes of limitation.

Claims

1. A polar alignment method, characterized in that: The polar alignment method comprises: Controlling the optical module of the imaging device to rotate around the horizontal rotation axis of the two-axis alignment device of the imaging device at a first altitude angle to obtain at least two celestial body images at different azimuth angles; Determining an adjustment amount based on at least two of the celestial body images and the target celestial pole position coordinates; wherein the adjustment amount is used to adjust the two-axis alignment device; The adjustment amount is updated based on the adjusted two-axis alignment device until the adjustment amount is within the allowable deviation range.

2. The method according to claim 1, characterized in that The updating of the adjustment amount based on the adjusted two-axis alignment device includes: Obtaining the actual change of the two-axis alignment device and determining the actual pointing coordinates of the horizontal rotation axis of the two-axis alignment device after adjustment; Determining a deviation between a current horizontal rotation axis and the target celestial pole based on the actual pointing coordinates and the target celestial pole position coordinates; The adjustment amount is updated according to the deviation amount.

3. The method according to claim 2, characterized in that in, The actual variation of the two-axis alignment device is obtained based on a gyroscope; When the adjustment amount is within the allowable deviation range, the current position is used as the zero position of the gyroscope.

4. The method according to claim 1, wherein The updating of the adjustment amount based on the adjusted two-axis alignment device includes: Changing the azimuth angle of the optical module again and acquiring an image of a celestial body; determining a deviation between a current horizontal rotation axis and the target celestial pole based on at least two most recent images of the celestial body and the coordinates of the target celestial pole position; The adjustment amount is updated according to the deviation amount.

5. The method according to claim 1, wherein After updating the adjustment amount based on the adjusted two-axis alignment device, the method further includes: Controlling the optical module of the imaging device to rotate around the horizontal rotation axis of the two-axis alignment device of the imaging device at a second altitude angle to obtain at least two celestial body images at different azimuth angles; Determining the deviation between the adjusted horizontal rotation axis of the two-axis alignment device and the target celestial pole based on at least two of the celestial body images and the target celestial pole position coordinates; According to the deviation, it is determined whether the adjustment amount is within the allowable deviation range.

6. The method according to claim 1, characterized in that The method further comprises: Monitoring change information of a two-axis alignment device, and judging whether the imaging device has a drastic posture change according to the change information of the two-axis alignment device; When it is determined that the imaging device has a drastic posture change, a prompt message for changing the alignment mode is generated.

7. The method according to claim 1, characterized in that Before acquiring at least two celestial body images at different azimuth angles obtained by rotating the optical module of the imaging device at the first altitude angle around the horizontal rotation axis of the two-axis alignment device of the imaging device, the method further includes: generating initial orientation adjustment information of the imaging device according to the target celestial pole position; The first altitude angle is generated according to the position coordinates of the imaging device.

8. An imaging device, characterized in that The imaging device includes a two-axis alignment device, an optical module and a control module; The two-axis alignment device is used to determine the pointing position of the optical module; The optical module is used to obtain at least two celestial body images when the horizontal rotation axis of the two-axis alignment device is at different azimuth angles of the target altitude angle; The control module is used to determine an adjustment amount based on at least two images of the celestial body and the coordinates of the target celestial pole position; wherein the adjustment amount is used to adjust the two-axis alignment device; The control module is further configured to update the adjustment amount based on the adjusted two-axis alignment device.

9. The imaging device according to claim 8, wherein The imaging device further includes a gyroscope; and the control module is specifically configured to: determining the actual pointing coordinates of the horizontal rotation axes of the two-axis alignment device after adjustment based on the actual change of the two-axis alignment device monitored by the gyroscope; Determining a deviation between a current horizontal rotation axis and the target celestial pole based on the actual pointing coordinates and the target celestial pole position coordinates; The adjustment amount is updated according to the deviation amount.

10. The imaging device according to claim 8, wherein The imaging device further includes a support module for an altitude angle indicating mechanism and an azimuth angle indicating mechanism; The two-axis alignment device is fixed to the support module; The altitude angle indicating mechanism is configured to display the altitude angle indicating number of the optical module, and the azimuth angle indicating mechanism is configured to display the azimuth angle indicating number of the optical module.

11. A computer program product, characterized in that The computer program product comprises a computer program / instruction, which implements the steps of the method according to any one of claims 1 to 7 when executed by a processor.

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