Calibration method and device of photoelectric theodolite, electronic equipment and storage medium

Abstract

The invention provides a calibration method and device of a photoelectric theodolite, electronic equipment and a storage medium, and relates to the technical field of photoelectric theodolites.An image frame corresponding to a target celestial body is obtained through the photoelectric theodolite, the actual pixel position of the target celestial body in the image frame is determined, and the photoelectric theodolite is calibrated according to the actual pixel position of the target celestial body in the image frame. The method comprises the following steps: determining actual directional angle information of a target celestial body, determining theoretical directional angle information of the target celestial body, and determining actual zero directional angle information of the photoelectric theodolite according to the actual directional angle information and the theoretical directional angle information of the target celestial body and initial zero directional angle information of the photoelectric theodolite so as to perform zero calibration on the photoelectric theodolite. According to the method, zero calibration is carried out without using a known fixed azimuth reference mark, so that the deployment area of the photoelectric theodolite is not limited, zero calibration can be carried out in an unsupported region, in addition, the type of a target celestial body for calibration is not limited, and all-day calibration can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric theodolites, and in particular to a calibration method, device, electronic equipment and storage medium for a photoelectric theodolite. Background Art

[0002] Photoelectric theodolites are widely used in astronomical observation, live image recording of flying targets, and pointing measurement. By rotating the azimuth and elevation axes, the photoelectric theodolite is pointed toward a space target, capturing an image of the target. Photoelectric theodolites typically incorporate azimuth and elevation axis angle encoders. These encoders must be zero-calibrated before operation.

[0003] In the related art, the axis angle encoder is calibrated using a known fixed azimuth benchmark or by photographing stars. However, when a photoelectric theodolite is deployed in an unsupported area and needs to quickly perform observation tasks, the axis angle encoder calibration is often difficult. There are no azimuth benchmarks available in the unsupported area, and the method of photographing stars places high demands on the detection capability of the photoelectric theodolite. Most stars cannot be observed by small and medium-sized photoelectric theodolites (400mm and below) due to their high apparent magnitude (dimmness), especially during the day. Therefore, the method of observing stars is not applicable. Summary of the Invention

[0004] The problem solved by the present invention is how to realize the zero-position calibration of a photoelectric theodolite at all times, without limiting the deployment area of the photoelectric theodolite.

[0005] To solve the above problems, the present invention provides a calibration method, device, electronic equipment and storage medium for a photoelectric theodolite.

[0006] In a first aspect, the present invention provides a calibration method for a photoelectric theodolite, comprising: Determining a target celestial body for calibration, and acquiring an image frame corresponding to the target celestial body through a photoelectric theodolite; Determining, based on the image frame corresponding to the target celestial object, an actual pixel position of the target celestial object in the image frame; determining actual pointing angle information of the target celestial object according to an actual pixel position of the target celestial object in the image frame; Determining theoretical pointing angle information of the target celestial body; According to the actual pointing angle information and theoretical pointing angle information of the target celestial body and the initial zero-position pointing angle information of the photoelectric theodolite, the actual zero-position pointing angle information of the photoelectric theodolite is determined to perform zero-position calibration on the photoelectric theodolite.

[0007] Optionally, the target celestial body is the sun or the moon; and determining, based on an image frame corresponding to the target celestial body, an actual pixel position of the target celestial body in the image frame includes: Performing edge detection in the image frame corresponding to the target celestial object to obtain a set of edge points corresponding to the outline of the target celestial object in the image frame; Determine the longest edge line corresponding to the edge point set, and judge whether the longest edge line is greater than a preset threshold; If the longest edge line is greater than or equal to a preset threshold, determining a convex hull point set in the longest edge line, and fitting a first circle according to the convex hull point set; If the longest edge line is smaller than the preset threshold, fitting a first circle according to the edge point set; Filtering the edge point set according to the first circle to obtain filtered edge points; A second circle is obtained by fitting the filtered edge points, and the actual pixel position of the target celestial body in the image frame is obtained based on the second circle.

[0008] Optionally, the preset threshold is half of the length of the image frame and half of the width of the image frame; and determining whether the longest edge line is greater than the preset threshold includes: It is determined whether the projected length of the longest edge line on the image frame is greater than half of the length of the image frame, and it is determined whether the projected width of the longest edge line on the image frame is greater than half of the width of the image frame.

[0009] Optionally, the target celestial body is a star; and determining, based on an image frame corresponding to the target celestial body, an actual pixel position of the target celestial body in the image frame includes: performing binarization processing on the image frame corresponding to the target celestial body to obtain a binarized image; The centroid of the target celestial object is determined according to the binarized image to obtain the actual pixel position of the target celestial object in the image frame.

[0010] Optionally, determining the actual pointing angle information of the target celestial object according to the actual pixel position of the target celestial object in the image frame includes: Determining pixel off-target information of the target celestial object according to an actual pixel position of the target celestial object in the image frame and a center pixel position of the image frame; Converting pixel miss information of the target celestial body into angular miss information of the target celestial body; The actual pointing angle information of the target celestial body is determined according to the angular miss information of the target celestial body and the pointing angle information of the photoelectric theodolite.

[0011] Optionally, determining the theoretical pointing angle information of the target celestial body includes: The theoretical pointing angle information of the target celestial body is determined according to the position of the photoelectric theodolite and the shooting time of the image frame.

[0012] Optionally, if the target celestial body is the sun, the lens of the photoelectric theodolite is at least covered with a Baader film.

[0013] In a second aspect, the present invention provides a calibration device for a photoelectric theodolite, comprising: An image acquisition module is used to determine a target celestial body for calibration and acquire an image frame corresponding to the target celestial body through a photoelectric theodolite; An actual pixel position determination module, configured to determine the actual pixel position of the target celestial object in the image frame according to the image frame corresponding to the target celestial object; an actual pointing determination module, configured to determine actual pointing angle information of the target celestial object based on an actual pixel position of the target celestial object in the image frame; A theoretical pointing determination module, configured to determine theoretical pointing angle information of the target celestial body; The zero position correction module is used to determine the actual zero position pointing angle information of the photoelectric theodolite according to the actual pointing angle information and theoretical pointing angle information of the target celestial body and the initial zero position pointing angle information of the photoelectric theodolite, so as to perform zero position calibration on the photoelectric theodolite.

[0014] In a third aspect, the present invention provides an electronic device comprising a memory and a processor; The memory is used to store computer programs; The processor is configured to implement the calibration method for the photoelectric theodolite as described in the first aspect when executing the computer program.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the calibration method of the photoelectric theodolite as described in the first aspect is implemented.

[0016] The photoelectric theodolite calibration method, device, electronic device, and storage medium of the present invention have the following beneficial effects: determining a target celestial body for calibration and obtaining an image frame corresponding to the target celestial body through the photoelectric theodolite. The type of target celestial body used for calibration is not limited, and compared to calibration that can only be performed at night using stars, calibration can be performed all day long. Based on the image frame corresponding to the target celestial body, the actual pixel position of the target celestial body in the image frame is determined, providing data support for the subsequent determination of the actual pointing angle information of the target celestial body. Based on the actual pixel position of the target celestial body in the image frame, the actual pointing angle information of the target celestial body and the theoretical pointing angle information of the target celestial body are determined. The actual pointing angle information of the target celestial body and the theoretical pointing angle information of the target celestial body are used to determine whether there is a deviation between the actual zero-position pointing angle information of the photoelectric theodolite and the initial zero-position pointing angle information. Based on the actual pointing angle information and the theoretical pointing angle information of the target celestial body, and the initial zero-position pointing angle information of the photoelectric theodolite, the actual zero-position pointing angle information of the photoelectric theodolite is determined to perform zero-position calibration on the photoelectric theodolite. The present invention does not require the use of known fixed azimuth reference marks for zero-position calibration, and therefore is not limited to the deployment area of the photoelectric theodolite, and can achieve zero-position calibration in an unsupported area. In addition, the present invention does not limit the type of target celestial body used for calibration, and can achieve calibration throughout the day. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of a calibration method for a photoelectric theodolite according to an embodiment of the present invention; Figure 2 A schematic diagram of zero position calibration of a photoelectric theodolite according to an embodiment; Figure 3 A flowchart of determining the actual pixel position of a target celestial object in an image frame according to an embodiment; Figure 4 A flowchart of determining the actual pixel position of a target celestial object in an image frame according to another embodiment; Figure 5 A flowchart of determining actual pointing angle information of a target celestial body according to an embodiment; Figure 6 A schematic diagram of pixel off-target information of a target celestial body according to an embodiment; Figure 7 Schematic diagram of the structure of a calibration device for a photoelectric theodolite according to an embodiment of the present invention; Figure 8 The figure is a schematic structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0019] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0020] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to"; the term "based on" means "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0021] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0022] The names of the messages or information exchanged between multiple devices in the embodiments of the present invention are only used for illustrative purposes and are not used to limit the scope of these messages or information.

[0023] In the related art, a method for calibrating a photoelectric theodolite using common celestial bodies involves first performing rough orientation by observing the edge of the sun or moon, and then performing secondary orientation by photographing the North Star. However, this method requires the edge of the sun or moon to assist in rough orientation, making it unusable on moonless nights. Furthermore, photographing the edge of the sun by the photoelectric theodolite can pose safety risks, such as detector damage, due to excessive light. Furthermore, the example used in this method uses a large-aperture photoelectric theodolite, and the apparent magnitude of the North Star is 1.98. Small and medium-aperture photoelectric theodolites have weaker detection capabilities and cannot detect the North Star during the day or under strong moonlight.

[0024] In related technology, a method for rapid autonomous orientation of a photoelectric theodolite involves using the photoelectric theodolite to photograph stars, then using a star map recognition algorithm and a star database to identify at least three stars in the field of view. Orientation is then performed using one of these identified stars. However, this requires specialized star map matching software and a large star database. Furthermore, due to the limited detection capabilities of small and medium-aperture photoelectric theodolites, they cannot capture more than three stars simultaneously in the field of view during the day or on moonlit nights, and therefore lack full-time capability.

[0025] In the related art, a field star calibration method for a photoelectric theodolite uses the photoelectric theodolite to photograph stars multiple times and uses the least squares method to solve the orientation error. However, this method does not take into account the initial calibration of the photoelectric theodolite. When the photoelectric theodolite is maneuvered to an unsupported area, it is impossible to introduce stars into the photoelectric theodolite's field of view due to the lack of initial coarse orientation. Similar to the aforementioned method, due to the limited detection capabilities of small and medium-aperture photoelectric theodolites, it is impossible to photograph enough stars for least squares fitting during the day or on a moonlit night.

[0026] In the related art, a high-precision autonomous orientation method for a mobile photoelectric theodolite adopts a combined orientation scheme of gyro coarse orientation and Polaris fine orientation. It requires the use of a dedicated gyroscope device, which is expensive and needs to be precisely installed on the theodolite turntable. Similarly, this method cannot be used when the photoelectric theodolite cannot observe the Polaris, and cannot be applied all day long.

[0027] In related technology, a zero-point calibration method for field optical measurement equipment based on the position of the sun involves installing a flat metal reference plate with a metal calibration rod on top of the theodolite's optical tube. The rod's projection under sunlight is used to determine rough orientation, and the North Star is used for secondary orientation. This method requires modifying the photoelectric theodolite, which is relatively cumbersome. It also cannot be used when there is no sun or when the photoelectric theodolite cannot observe the North Star, and lacks full-time capability.

[0028] In response to the problems existing in the above-mentioned related technologies, this embodiment provides a calibration method, device, electronic device and storage medium for a photoelectric theodolite.

[0029] like Figure 1 As shown, an embodiment of the present invention provides a calibration method for a photoelectric theodolite, comprising the following steps: S100: Determine a target celestial body for calibration, and obtain an image frame corresponding to the target celestial body through a photoelectric theodolite.

[0030] Specifically, the target celestial body can be any of the sun, moon, and stars. During the day, the target celestial body used for calibration is the sun; at night, the target celestial bodies used for calibration are the moon and stars. The moon is preferred as the target celestial body, and stars are selected as target celestial bodies when there is no moon at night. The apparent magnitude of the sun is approximately -26.70, and the apparent magnitude of the moon at full moon is -13.00. The apparent diameter of the sun is between 31.6 and 32.7 arc minutes, and the apparent diameter of the moon is between 29.3 and 33.4 arc minutes. Both are large surface targets, very visible in the sky, and easy to find and introduce into the field of view of the photoelectric theodolite. To address the weak detection capabilities of small-aperture photoelectric theodolites, this embodiment selects stars with higher apparent magnitudes, such as Sirius (-1.46), Alpha Centauri (-0.3), Arcturus (-0.04), Vega (0.03), Capella (0.08), and Rigel (0.12). These stars have high apparent magnitudes and are easy to find in the sky, making them suitable targets for calibration in the evening or at night. Magnitude represents the brightness of a celestial object as observed from Earth; the higher the apparent magnitude, the brighter the object appears.

[0031] Specifically, the target celestial body is tracked and photographed by a photoelectric theodolite to obtain a plurality of consecutive image frames of the target celestial body. The photoelectric theodolite in the embodiment of the present application is a photoelectric theodolite of small or medium aperture (400 mm or less).

[0032] S200: Determine the actual pixel position of the target celestial object in the image frame according to the image frame corresponding to the target celestial object.

[0033] Specifically, the actual pixel position of the target celestial object in the image frame is the pixel coordinate of the target celestial object in the image coordinate system of the image frame, wherein the image coordinate system uses a preset position in the image frame (for example, the center position of the image frame) as the origin, the horizontal right direction (column direction) of the image frame as the X-axis, and the vertical downward direction (row direction) of the image frame as the Y-axis.

[0034] Specifically, the actual pixel position of the target celestial object in the image frame may be the actual pixel position of the center point of the target celestial object in the image frame.

[0035] S300: Determine actual pointing angle information of the target celestial object according to the actual pixel position of the target celestial object in the image frame.

[0036] Specifically, the actual pointing angle information of the target celestial body refers to the angle in space of the direction vector from the photoelectric theodolite to the target celestial body, which may include: the actual angle in the azimuth direction and the actual angle in the pitch direction, which is defined based on the horizontal coordinate system. In the horizontal coordinate system, the actual angle in the azimuth direction is the horizontal angle rotated clockwise from the reference direction (usually due north) to the direction of the target celestial body, and the actual angle in the pitch direction is the vertical angle of the direction of the target celestial body relative to the horizontal plane.

[0037] Ideally, the target celestial object in the image frame acquired by the photoelectric theodolite should be located at the center pixel position of the image frame, that is, the pixel position corresponding to the center point of the image frame. However, due to the zero position error of the photoelectric theodolite in actual situations, there is a pixel miss amount between the actual pixel position of the target celestial object in the image frame and the center pixel position of the image frame. Therefore, the actual pointing angle information of the target celestial object can be obtained based on the pixel miss amount and the angle value corresponding to each pixel in the image frame.

[0038] S400: Determine theoretical pointing angle information of the target celestial body.

[0039] Specifically, the theoretical pointing angle information of the target celestial body refers to the angular information of the expected direction of the target celestial body calculated based on a reference coordinate system (such as a horizontal coordinate system or an equatorial coordinate system) in astronomical observation or space navigation, which may include: the theoretical angle of the azimuth direction and the theoretical angle of the pitch direction.

[0040] Specifically, the theoretical pointing angle information of the target celestial body can be calculated using an existing method for calculating the apparent position of a celestial body according to the position of the photoelectric theodolite and the shooting time of the image frame, which will not be described in detail in this embodiment.

[0041] S500: Determine the actual zero-position pointing angle information of the photoelectric theodolite according to the actual pointing angle information and the theoretical pointing angle information of the target celestial body and the initial zero-position pointing angle information of the photoelectric theodolite, so as to perform zero-position calibration on the photoelectric theodolite.

[0042] Specifically, the initial zero-point pointing angle information of a photoelectric theodolite refers to the zero-point pointing angle information of the photoelectric theodolite's encoder. This refers to the reference angle defined by the encoder during initial calibration. This information typically includes initial zero degrees in azimuth and initial zero degrees in elevation, and is used to calibrate the starting direction of measurement. Due to mechanical installation errors, environmental and time-related factors, and electronic system errors, the initial zero degrees in azimuth and elevation during initial calibration may deviate from the actual zero degree, known as zero-point deviation. Therefore, the actual zero-point pointing angle information of the photoelectric theodolite (i.e., actual zero degrees in azimuth and elevation) must be calculated to perform zero-point calibration.

[0043] Specifically, based on the actual pointing angle information and theoretical pointing angle information of the target celestial body, the deviation between the two can be obtained. This deviation is also the deviation between the initial zero-position pointing angle information and the actual zero-position pointing angle information. That is, through the deviation between the actual pointing angle information and the theoretical pointing angle information of the target celestial body, combined with the initial zero-position pointing angle information of the photoelectric theodolite, the actual zero-position pointing angle information of the photoelectric theodolite can be calculated. For ease of understanding, the embodiment of the present application provides the following exemplary method for calculating the actual zero-position pointing angle information of the photoelectric theodolite, such as Figure 2 As shown, point A is the initial zero position, and the initial zero pointing angle information is A_0 and E_0. A_0 is the initial zero angle in the azimuth direction, and E_0 is the initial zero angle in the elevation direction. Point B is the actual position of the target celestial body, and the actual pointing angle information is A_measure and E_measure. A_measure is the actual angle in the azimuth direction, and E_measure is the actual angle in the elevation direction. Point C is the theoretical position of the target celestial body, and the theoretical pointing angle information is A_theory and E_theory. A_theory is the theoretical angle in the azimuth direction, and E_ theory is the theoretical angle in the pitch direction, point D is the pointing position of the photoelectric theodolite, that is, the pointing position of the photoelectric theodolite when photographing the target celestial body. The corresponding position information is the pointing angle information of the photoelectric theodolite, including A_code and E_code. A_code is the pointing angle of the photoelectric theodolite encoder in the azimuth direction when photographing the target celestial body, and E_code is the pointing angle of the photoelectric theodolite encoder in the pitch azimuth when photographing the target celestial body. It should be noted that the pointing position of the photoelectric theodolite is located at the center of the image frame after being converted from the horizontal coordinates to the image coordinate system where the image frame is located. Specifically, the actual zero-position pointing angle information (A0, E0) can be calculated using the following expression: A0=A_0+(A_theory-A_measure); E0=E_0+(E_theory-E_measure); Among them, A0 is the actual zero angle in the azimuth direction, and E0 is the actual zero angle in the elevation direction.

[0044] In this embodiment, a target celestial body for calibration is determined, and an image frame corresponding to the target celestial body is acquired using a photoelectric theodolite. The type of target celestial body used for calibration is not limited. Compared to calibration that can only be performed at night using stars, calibration can be performed all day long. Based on the image frame corresponding to the target celestial body, the actual pixel position of the target celestial body in the image frame is determined, providing data support for the subsequent determination of the target celestial body's actual pointing angle information. Based on the actual pixel position of the target celestial body in the image frame, the actual pointing angle information of the target celestial body is determined, as well as the theoretical pointing angle information of the target celestial body. The actual pointing angle information of the target celestial body and the theoretical pointing angle information of the target celestial body are used to determine whether there is a deviation between the actual zero-position pointing angle information of the photoelectric theodolite and the initial zero-position pointing angle information. Based on the actual and theoretical pointing angle information of the target celestial body and the initial zero-position pointing angle information of the photoelectric theodolite, the actual zero-position pointing angle information of the photoelectric theodolite is determined, thereby performing zero-position calibration on the photoelectric theodolite. The present invention does not require the use of known fixed azimuth reference marks for zero-position calibration, and therefore is not limited to the deployment area of the photoelectric theodolite, and can achieve zero-position calibration in an unsupported area. In addition, the present invention does not limit the type of target celestial body used for calibration, and can achieve calibration throughout the day.

[0045] Optionally, the target celestial body is the sun or the moon. Since both the sun and the moon can be regarded as perfect circles, the center pixel position of the sun or the moon in the image frame can be calculated using a circle fitting method, that is, the actual pixel position of the sun or the moon can be obtained.

[0046] like Figure 3 As shown, according to the image frame corresponding to the target celestial object, determining the actual pixel position of the target celestial object in the image frame includes the following steps: S310: Perform edge detection in the image frame corresponding to the target celestial object to obtain a set of edge points corresponding to the outline of the target celestial object in the image frame.

[0047] Due to the high intensity of sunlight, the photoelectric theodolite cannot directly photograph the sun, which may burn the detector. The sunlight needs to be filtered. Therefore, when the target celestial body is the sun, the lens of the photoelectric theodolite is equipped with a Baader film with a density of 5.0 on the basis of the original structure. This can attenuate the transmitted solar energy to about 10^-5 of its original value, effectively ensuring the safe imaging of the sun by the photoelectric theodolite.

[0048] In addition, before edge detection is performed on the image frame, the image frame must first be filtered to remove noise from the image frame. The filtering process may be an existing image filtering method, such as Gaussian filtering.

[0049] Specifically, the purpose of edge detection is to identify the intensity mutation area between the target celestial body and the background in the image frame (such as a sharp change in brightness or color). The image frame obtained after edge detection will retain the detected edges, while other areas (non-edges) will be suppressed. For example, the image obtained after edge detection is a binary image, in which the detected edges are assigned white (255) and non-edges are assigned black (0). For another example, the image obtained after edge detection is a grayscale image, and the intensity of the edge pixels reflects the gradient amplitude. For example, the edge area is different gray levels, and the non-edge is close to black. Among them, the edge pixels in the image after edge detection are the edge point set corresponding to the outline of the target celestial body in the image frame.

[0050] Specifically, the method for performing edge detection in the image frame corresponding to the target celestial body may be an existing edge detection method, for example, a Canny edge detection method.

[0051] S320: Determine the longest edge line corresponding to the edge point set, and judge whether the longest edge line is greater than a preset threshold.

[0052] Due to the limitations of the quality of the image frames acquired by the photoelectric theodolite and some influences of the edge detection algorithm, the edge points in the detected image frames may contain noise and the edges of other small targets in space. Therefore, by determining the longest edge line and comparing the longest edge line with the preset threshold, noise and small targets can be filtered out to ensure that the detected longest edge line corresponds to the target celestial body in the image frame.

[0053] In some embodiments, the preset threshold can be half the length of the image frame and half the width of the image frame to ensure that the edge line of the detected target celestial body is large and significant enough, avoid interference from small-size noise or debris, and balance detection sensitivity and false detection rate.

[0054] In some embodiments, determining whether the longest edge line is greater than a preset threshold includes: It is determined whether the projected length of the longest edge line on the image frame is greater than half the length of the image frame, and it is determined whether the projected width of the longest edge line on the image frame is greater than half the width of the image frame.

[0055] S330: If the longest edge line is greater than or equal to a preset threshold, determine a convex hull point set in the longest edge line, and obtain a first circle by fitting the convex hull point set.

[0056] Specifically, when the longest edge line detected in an image frame is greater than or equal to a preset threshold, it can be determined that this longest edge line corresponds to the target celestial object. To further analyze the geometric characteristics of the target celestial object, the convex hull point set of this longest edge line (i.e., the vertices of the outermost convex polygon enclosing the longest edge line) is extracted to eliminate local edge depressions or noise interference. Based on this convex hull point set, a first circle is fitted using the least squares method or a similar algorithm to obtain the approximate center and radius of the target celestial object.

[0057] S340: If the longest edge line is smaller than a preset threshold, a first circle is obtained by fitting according to the edge point set.

[0058] Specifically, when the longest edge line is smaller than a preset threshold, it indicates that the target object may be small or have an incomplete edge (e.g., an incomplete lunar phase, noise, or a broken edge due to unclear imaging). In this case, the first circle is fitted directly based on the original edge point set (rather than the convex hull) to preserve more detailed local features.

[0059] S350: Filter the edge point set according to the first circle to obtain filtered edge points.

[0060] Specifically, after obtaining the first circle, the original edge point set is screened based on geometric consistency, abnormal points that deviate too far from the first circle (such as noise or non-target structures) are eliminated, and edge points distributed within a reasonable neighborhood of the first circle are retained (such as setting the threshold to be within ±2 pixels of the radius from the center of the circle).

[0061] S360: Obtain a second circle by fitting the filtered edge points, and obtain the actual pixel position of the target celestial body in the image frame based on the second circle.

[0062] Specifically, the second circle is refitted using the filtered edge points (for example, using the least squares method). In this case, the fitting result is more accurate and can effectively suppress the interference of outliers in the initial edge point set.

[0063] Specifically, the center of the second circle is used as the actual pixel position of the target celestial object in the image frame.

[0064] In this optional embodiment, for the target celestial body of the sun or the moon, since the sun and the moon are surface targets, it is difficult to select the calibration point when used for zero-position calibration, and they cannot be used directly for calibration. It is necessary to calculate the centroid of the sun and the moon as the calibration point; and the apparent diameter of the sun and the moon are both about 30 arc minutes, and there may be uneven brightness of the image, non-full moon, etc. during imaging, and the centroid of the sun and the moon cannot be directly calculated using the binarization method. Therefore, the embodiment of the present application provides a method for effectively determining the centroid position of the sun and the moon to accurately obtain the actual pixel position of the sun or the moon in the image frame.

[0065] Optionally, the target celestial body is a star.

[0066] like Figure 4 As shown, according to the image frame corresponding to the target celestial object, determining the actual pixel position of the target celestial object in the image frame includes the following steps: S410: Binarizing the image frame corresponding to the target celestial body to obtain a binarized image.

[0067] Specifically, the target celestial body in the image frame is binarized and segmented to separate it from the background, thereby obtaining a binarized image. In one embodiment, the pixel values of the binarized image are 0 (pure black, background) and 255 (pure white, target celestial body).

[0068] S420: Determine the centroid of the target celestial object based on the binarized image to obtain the actual pixel position of the target celestial object in the image frame.

[0069] Specifically, based on the binarized image, the geometric centroid of the binary connected region is calculated to obtain the actual pixel position of the target celestial body in the image frame.

[0070] Specifically, since stars are generally point targets when being imaged, a binarization method can be used to find the centroid and obtain the actual pixel position of the star in the image frame.

[0071] In this optional embodiment, when the target celestial body is a star, a binarization method is used to obtain the centroid of the star, which is simple and efficient and suitable for rapid positioning of the star in the image frame.

[0072] Alternatively, as Figure 5 As shown, determining the actual pointing angle information of the target celestial body according to the actual pixel position of the target celestial body in the image frame includes the following steps: S510: Determine pixel off-target information of the target celestial object according to the actual pixel position of the target celestial object in the image frame and the center pixel position of the image frame.

[0073] S520: Convert the pixel miss information of the target celestial body into the angular miss information of the target celestial body.

[0074] S530: Determine actual pointing angle information of the target celestial body according to the angular miss information of the target celestial body and the pointing angle information of the photoelectric theodolite.

[0075] In some embodiments, as Figure 6As shown in the figure, the pixel miss information of the target object is Δpx and Δpy, where Δpx is the pixel miss information in the azimuth direction and Δpy is the pixel miss information in the elevation direction. The pixel equivalents in the azimuth and elevation directions in the image frame are A_equivalents and E_equivalents, respectively. The pixel equivalent is the angle information corresponding to each pixel in the image frame. The angular miss information (Δx, Δy) of the target object is calculated according to the following expression: Δx=Δpx*A_equivalents*sec(E_code); Δy=Δpy*E_equivalents; Wherein, Δx is the angular miss information in the azimuth direction, Δy is the angular miss information in the elevation direction, and E_code is the pointing angle of the encoder of the photoelectric theodolite in the elevation direction when photographing the target celestial body.

[0076] Based on the target celestial body's angular miss information (Δx, Δy) calculated above, the target celestial body's actual angle in azimuth is A_measure = A_code + Δx, and the target celestial body's actual angle in elevation is E_measure = E_code + Δy. A_code is the azimuth angle of the photoelectric theodolite's encoder when photographing the target celestial body, and E_code is the elevation angle of the photoelectric theodolite's encoder when photographing the target celestial body. A_code and E_code are the pointing angle information of the photoelectric theodolite, and A_measure and E_measure are the actual pointing angle information of the target celestial body.

[0077] In this optional embodiment, the actual pixel position of the target celestial object in the image frame is converted into the angular miss information of the target celestial object in the horizontal coordinate system, thereby obtaining the actual pointing angle information of the target celestial object in the horizontal coordinate system, thereby realizing the conversion of the position of the target celestial object from the image coordinate system to the horizontal coordinate system to obtain the actual pointing angle information of the target celestial object in the horizontal coordinate system.

[0078] like Figure 7 As shown, an embodiment of the present invention provides a calibration device 700 for a photoelectric theodolite, comprising: An image acquisition module 710 is configured to determine a target celestial body for calibration and acquire an image frame corresponding to the target celestial body through a photoelectric theodolite; The actual pixel position determination module 720 is configured to determine the actual pixel position of the target celestial object in the image frame according to the image frame corresponding to the target celestial object; An actual pointing determination module 730 is configured to determine actual pointing angle information of the target celestial object based on the actual pixel position of the target celestial object in the image frame; Theoretical pointing determination module 740 is used to determine the theoretical pointing angle information of the target celestial body; The zero position correction module 750 is used to determine the actual zero position pointing angle information of the photoelectric theodolite based on the actual pointing angle information and theoretical pointing angle information of the target celestial body and the initial zero position pointing angle information of the photoelectric theodolite, so as to perform zero position calibration on the photoelectric theodolite.

[0079] Optionally, the target celestial body is the sun or the moon; and determining, based on an image frame corresponding to the target celestial body, an actual pixel position of the target celestial body in the image frame includes: Performing edge detection in the image frame corresponding to the target celestial object to obtain a set of edge points corresponding to the outline of the target celestial object in the image frame; Determine the longest edge line corresponding to the edge point set, and judge whether the longest edge line is greater than a preset threshold; If the longest edge line is greater than or equal to a preset threshold, determining a convex hull point set in the longest edge line, and fitting a first circle according to the convex hull point set; If the longest edge line is smaller than the preset threshold, fitting a first circle according to the edge point set; Filtering the edge point set according to the first circle to obtain filtered edge points; A second circle is obtained by fitting the filtered edge points, and the actual pixel position of the target celestial body in the image frame is obtained based on the second circle.

[0080] Optionally, the preset threshold is half of the length of the image frame and half of the width of the image frame; and determining whether the longest edge line is greater than the preset threshold includes: It is determined whether the projected length of the longest edge line on the image frame is greater than half of the length of the image frame, and it is determined whether the projected width of the longest edge line on the image frame is greater than half of the width of the image frame.

[0081] Optionally, the target celestial body is a star; and determining, based on an image frame corresponding to the target celestial body, an actual pixel position of the target celestial body in the image frame includes: performing binarization processing on the image frame corresponding to the target celestial body to obtain a binarized image; The centroid of the target celestial object is determined according to the binarized image to obtain the actual pixel position of the target celestial object in the image frame.

[0082] Optionally, determining the actual pointing angle information of the target celestial object according to the actual pixel position of the target celestial object in the image frame includes: Determining pixel off-target information of the target celestial object according to an actual pixel position of the target celestial object in the image frame and a center pixel position of the image frame; Converting pixel miss information of the target celestial body into angular miss information of the target celestial body; The actual pointing angle information of the target celestial body is determined according to the angular miss information of the target celestial body and the pointing angle information of the photoelectric theodolite.

[0083] Optionally, determining the theoretical pointing angle information of the target celestial body includes: The theoretical pointing angle information of the target celestial body is determined according to the position of the photoelectric theodolite and the shooting time of the image frame.

[0084] Optionally, if the target celestial body is the sun, the lens of the photoelectric theodolite is at least covered with a Baader film.

[0085] like Figure 8 As shown, an electronic device 800 provided by an embodiment of the present invention includes a memory 810 and a processor 820; the memory 810 is used to store a computer program; the processor 820 is used to implement the calibration method of the photoelectric theodolite as described above when executing the computer program.

[0086] In other words, an electronic device 800 includes a memory 810 and a processor 820 coupled to the memory 810; the memory 810 is configured to store a computer program; and the processor 820 is configured to perform the following operations when executing the computer program: Determining a target celestial body for calibration, and acquiring an image frame corresponding to the target celestial body through a photoelectric theodolite; Determining, based on the image frame corresponding to the target celestial object, an actual pixel position of the target celestial object in the image frame; determining actual pointing angle information of the target celestial object according to an actual pixel position of the target celestial object in the image frame; Determining theoretical pointing angle information of the target celestial body; According to the actual pointing angle information and theoretical pointing angle information of the target celestial body and the initial zero-position pointing angle information of the photoelectric theodolite, the actual zero-position pointing angle information of the photoelectric theodolite is determined to perform zero-position calibration on the photoelectric theodolite.

[0087] An embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the calibration method of the photoelectric theodolite as described above is implemented.

[0088] In other words, a non-volatile computer-readable storage medium stores a computer program, which, when executed by a processor, causes the processor to perform the following operations: Determining a target celestial body for calibration, and acquiring an image frame corresponding to the target celestial body through a photoelectric theodolite; Determining, based on the image frame corresponding to the target celestial object, an actual pixel position of the target celestial object in the image frame; determining actual pointing angle information of the target celestial object according to an actual pixel position of the target celestial object in the image frame; Determining theoretical pointing angle information of the target celestial body; According to the actual pointing angle information and theoretical pointing angle information of the target celestial body and the initial zero-position pointing angle information of the photoelectric theodolite, the actual zero-position pointing angle information of the photoelectric theodolite is determined to perform zero-position calibration on the photoelectric theodolite.

[0089] An electronic device 800 that can serve as a server or client of the present invention will now be described, which is an example of a hardware device that can be applied to various aspects of the present invention. The electronic device 800 is intended to represent various forms of digital electronic computer equipment, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device 800 can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0090] Electronic device 800 includes a computing unit that can perform various appropriate actions and processes based on a computer program stored in a read-only memory (ROM) or loaded from a storage unit into a random access memory (RAM). The RAM can also store various programs and data required for device operation. The computing unit, ROM, and RAM are interconnected via a bus. An input / output (I / O) interface is also connected to the bus.

[0091] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM). In this application, the units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network elements. Some or all of these units can be selected based on actual needs to achieve the objectives of the embodiments of the present invention. Furthermore, the functional units in the various embodiments of the present invention can be integrated into a single processing unit, each unit can exist physically separately, or two or more units can be integrated into a single unit. These integrated units can be implemented in either hardware or software functional units.

[0092] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A calibration method for a photoelectric theodolite, characterized in that: include: Determining a target celestial body for calibration, and acquiring an image frame corresponding to the target celestial body through a photoelectric theodolite; Determining, based on the image frame corresponding to the target celestial object, an actual pixel position of the target celestial object in the image frame; determining actual pointing angle information of the target celestial object according to an actual pixel position of the target celestial object in the image frame; Determining theoretical pointing angle information of the target celestial body; According to the actual pointing angle information and theoretical pointing angle information of the target celestial body and the initial zero-position pointing angle information of the photoelectric theodolite, the actual zero-position pointing angle information of the photoelectric theodolite is determined to perform zero-position calibration on the photoelectric theodolite.

2. The calibration method of the photoelectric theodolite according to claim 1, characterized in that: The target celestial body is the sun or the moon; and determining, based on the image frame corresponding to the target celestial body, the actual pixel position of the target celestial body in the image frame includes: Performing edge detection in the image frame corresponding to the target celestial object to obtain a set of edge points corresponding to the outline of the target celestial object in the image frame; Determine the longest edge line corresponding to the edge point set, and judge whether the longest edge line is greater than a preset threshold; If the longest edge line is greater than or equal to a preset threshold, determining a convex hull point set in the longest edge line, and fitting a first circle according to the convex hull point set; If the longest edge line is smaller than the preset threshold, fitting a first circle according to the edge point set; Filtering the edge point set according to the first circle to obtain filtered edge points; A second circle is obtained by fitting the filtered edge points, and the actual pixel position of the target celestial body in the image frame is obtained based on the second circle.

3. The calibration method of the photoelectric theodolite according to claim 2, characterized in that: The preset threshold is half of the length of the image frame and half of the width of the image frame; and determining whether the longest edge line is greater than the preset threshold includes: It is determined whether the projected length of the longest edge line on the image frame is greater than half of the length of the image frame, and it is determined whether the projected width of the longest edge line on the image frame is greater than half of the width of the image frame.

4. The calibration method of the photoelectric theodolite according to claim 2, characterized in that: The target celestial body is a star; The determining, based on the image frame corresponding to the target celestial object, an actual pixel position of the target celestial object in the image frame includes: performing binarization processing on the image frame corresponding to the target celestial body to obtain a binarized image; The centroid of the target celestial object is determined according to the binarized image to obtain the actual pixel position of the target celestial object in the image frame.

5. The calibration method of the photoelectric theodolite according to claim 1, characterized in that: Determining the actual pointing angle information of the target celestial object according to the actual pixel position of the target celestial object in the image frame includes: Determining pixel off-target information of the target celestial object according to an actual pixel position of the target celestial object in the image frame and a center pixel position of the image frame; Converting pixel miss information of the target celestial body into angular miss information of the target celestial body; The actual pointing angle information of the target celestial body is determined according to the angular miss information of the target celestial body and the pointing angle information of the photoelectric theodolite.

6. The calibration method of the photoelectric theodolite according to claim 1, characterized in that: Determining the theoretical pointing angle information of the target celestial body includes: The theoretical pointing angle information of the target celestial body is determined according to the position of the photoelectric theodolite and the shooting time of the image frame.

7. The calibration method of a photoelectric theodolite according to any one of claims 1 to 6, characterized in that: If the target celestial body is the sun, the lens of the photoelectric theodolite is at least covered with a Baader film.

8. A calibration device for a photoelectric theodolite, characterized in that: include: An image acquisition module is used to determine a target celestial body for calibration and acquire an image frame corresponding to the target celestial body through a photoelectric theodolite; An actual pixel position determination module, configured to determine the actual pixel position of the target celestial object in the image frame according to the image frame corresponding to the target celestial object; an actual pointing determination module, configured to determine actual pointing angle information of the target celestial object based on an actual pixel position of the target celestial object in the image frame; A theoretical pointing determination module, configured to determine theoretical pointing angle information of the target celestial body; The zero position correction module is used to determine the actual zero position pointing angle information of the photoelectric theodolite according to the actual pointing angle information and theoretical pointing angle information of the target celestial body and the initial zero position pointing angle information of the photoelectric theodolite, so as to perform zero position calibration on the photoelectric theodolite.

9. An electronic device, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is configured to implement the calibration method for a photoelectric theodolite according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and when the computer program is executed by the processor, the calibration method of the photoelectric theodolite according to any one of claims 1 to 7 is implemented.

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