Satellite laser altimetry positioning method, device and electronic equipment under complex terrain

Abstract

The present invention provides a method, device and electronic equipment for satellite laser altimetry positioning under complex terrain, belonging to the field of satellite laser positioning. The method includes: obtaining a footprint image of a laser footprint to be measured, a laser echo signal and the corresponding image point coordinates of the laser footprint to be measured in the footprint image; performing image segmentation on the footprint image to obtain a ground object segmentation image, constructing a multi-component echo energy model based on the laser echo signal, determining the optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model and the image point coordinates; and solving the altimetry positioning result based on the optimal Gaussian component. The present invention can flexibly select Gaussian components by performing image segmentation on the footprint image to obtain a ground object segmentation image in satellite laser altimetry under the full waveform laser altimeter plus laser footprint camera mode. It can effectively select the nearest Gaussian component of satellite laser altimetry under various complex terrains, effectively reducing the error of satellite laser altimetry.

Description

Technical Field

[0001] The present invention relates to the field of satellite laser positioning technology, and in particular to a satellite laser altimetry positioning method, device and electronic equipment under complex terrain. Background Art

[0002] Satellite laser altimetry, as an active remote sensing technology, provides a new means of satellite remote sensing observation. By measuring the round-trip time between the laser beam emitted by the laser and the Earth, combined with information such as the satellite platform's orbital position and attitude, it is possible to calculate the target surface elevation with decimeter or even centimeter-level accuracy. A laser altimeter system, using a full-waveform laser altimeter coupled with a laser footprint camera, is currently an advanced laser altimeter mode. It emits a laser beam and fully records the return signal from ground objects, while simultaneously capturing images of objects in the area surrounding the laser footprint. By measuring the round-trip time between the laser beam and the Earth, combined with information such as the satellite platform's orbital position, attitude, and laser pointing, the surface elevation at the laser footprint can be calculated. However, in a satellite laser altimeter system, the laser pulses emitted by the laser altimeter reach the surface, leaving a footprint that can reach tens of meters in diameter. A satellite laser altimeter footprint can contain a variety of features, such as exposed ground, buildings, trees, and rivers. The overlapping of these features can result in inconsistent heights within the footprint. A full-waveform satellite laser altimeter can fully record the echoes of the features within the footprint. Multiple features will cause the echo waveform to exhibit multiple peaks. Therefore, determining the optimal Gaussian component corresponding to the laser ranging vector is essential for ensuring accurate positioning in satellite laser altimeter measurements over complex terrain.

[0003] Existing techniques for determining the optimal echo components for complex terrain typically rely on empirical analysis. Current selection methods include: selecting the last Gaussian component in the echo waveform decomposition, i.e., using the time-center-of-gravity parameters of the Gaussian component with the largest temporal center of gravity among the Gaussian component parameters to calculate the distance from the satellite to the target; selecting the second-to-last Gaussian component, i.e., using the time-center-of-gravity parameters of the Gaussian component with the second-largest temporal center of gravity among the Gaussian component parameters to calculate the distance from the satellite to the target; selecting the Gaussian component with the largest amplitude, i.e., using the time-center-of-gravity parameters of the Gaussian component with the largest amplitude among the Gaussian component parameters to calculate the distance from the satellite to the target; and selecting the Gaussian component with the largest integrated area (indirectly equivalent to the echo energy), i.e., using the time-center-of-gravity parameters of the Gaussian component with the largest integrated area among the Gaussian components to calculate the distance from the satellite to the target. However, the morphological characteristics of the satellite laser altimeter echo waveform are closely related not only to the distribution of terrain heights within the footprint, but also to the planar position distribution of features at different heights within the footprint, the reflectivity of different features, and the geometry of the features. It is difficult to accurately select the optimal Gaussian component corresponding to the emitted laser vector based only on a certain waveform characteristic parameter, resulting in large errors in satellite laser altimetry and positioning in the full-waveform laser altimeter plus laser footprint camera mode.

[0004] Therefore, the existing technology has the problem that in satellite laser altimetry, it is difficult to accurately select the optimal Gaussian component corresponding to the emitted laser vector based only on a certain waveform characteristic parameter, resulting in a large elevation error in satellite laser altimetry positioning under complex terrain, which needs to be improved. Summary of the Invention

[0005] In view of this, it is necessary to provide a satellite laser altimetry positioning method, device and electronic equipment under complex terrain to solve the technical problem in the prior art that it is difficult to accurately select the optimal Gaussian component corresponding to the emitted laser vector based on a certain waveform characteristic parameter in satellite laser altimetry positioning, resulting in large errors in satellite laser altimetry positioning.

[0006] In order to solve the above problems, on the one hand, the present invention provides a satellite laser altimetry positioning method under complex terrain, comprising:

[0007] Obtaining a footprint image of the laser foot point to be measured, a laser echo signal, and the coordinates of the corresponding image point of the laser foot point to be measured in the footprint image;

[0008] Perform image segmentation on the footprint image to obtain a ground object segmentation image, construct a multi-component echo energy model based on the laser echo signal, and determine the optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates;

[0009] The altimetry positioning results are solved based on the optimal Gaussian component.

[0010] In a possible implementation, the multi-component echo energy model includes a plurality of echo components, the ground object segmentation image includes a plurality of segmentation sub-images, and the number of the echo components is equal to the number of the segmentation sub-images.

[0011] In one possible implementation, performing image segmentation on the footprint image to obtain a ground object segmentation image includes:

[0012] The footprint image is segmented according to the pixel brightness information of the footprint image to obtain the ground feature segmentation image.

[0013] In one possible implementation, a multi-component echo energy model is constructed based on the laser echo signal, including:

[0014] Construct the multi-component echo photon equation of the object to be measured according to the laser echo signal;

[0015] The multi-component echo photon equation is simplified to obtain the multi-component echo energy model.

[0016] In one possible implementation, determining the optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates includes:

[0017] Matching the echo component with the segmentation sub-image to obtain matching information;

[0018] The optimal Gaussian component is determined based on the matching information and the image point coordinates.

[0019] In a possible implementation, performing information matching on the echo component and the segmented sub-image to obtain matching information includes:

[0020] Determine the integrated area of ​​each echo component according to the multi-component echo energy model, and determine the pixel brightness value of each segmented sub-image according to the ground object segmentation image;

[0021] Sorting the integrated areas obtains the echo component sorting information, and sorting the pixel brightness values ​​obtains the segmentation sub-image sorting information;

[0022] Matching information is performed on the echo component sorting information and the segmentation sub-image sorting information to obtain matching information.

[0023] In one possible implementation, the satellite laser altimetry positioning method under complex terrain further includes:

[0024] The segmented sub-image corresponding to the pixel coordinates is used as the current sub-image. If the distance between the pixel coordinates and the adjacent sub-image of the current sub-image is less than a preset distance threshold or the difference in pixel brightness between the current sub-image and the adjacent sub-image of the current sub-image is less than a preset brightness threshold, the adjacent sub-image is used as a candidate sub-image.

[0025] determining the surface characteristic parameters of the current sub-image and the surface characteristic parameters of the candidate sub-images according to the multi-component echo energy model;

[0026] If the surface feature parameters of the current sub-image are smaller than those of the candidate sub-image, the laser foot point to be measured is moved to the corresponding area of ​​the candidate sub-image, and the geodetic coordinates of the laser foot point to be measured after the movement are calculated.

[0027] On the other hand, the present invention also provides a satellite laser altimetry positioning device under complex terrain, comprising:

[0028] A signal acquisition unit, used to acquire a footprint image of the laser foot point to be measured, a laser echo signal, and the coordinates of the corresponding image point of the laser foot point to be measured in the footprint image;

[0029] An optimal Gaussian component determination unit is used to perform image segmentation on the footprint image to obtain a ground object segmentation image, construct a multi-component echo energy model based on the laser echo signal, and determine the optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model and the image point coordinates;

[0030] The altimetry positioning solution unit is used to solve the altimetry positioning result according to the optimal Gaussian component.

[0031] On the other hand, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and runnable on the processor. When the processor executes the program, the above-mentioned satellite laser altimetry positioning method under complex terrain is implemented.

[0032] On the other hand, the present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned satellite laser altimetry positioning method under complex terrain is implemented.

[0033] The beneficial effects of the present invention are as follows: in the satellite laser altimetry positioning method under complex terrain provided by the present invention, first, a footprint image of the laser footprint to be measured, a laser echo signal, and the corresponding image point coordinates of the laser footprint to be measured in the footprint image are obtained; then, the footprint image is segmented to obtain a ground object segmentation image, a multi-component echo energy model is constructed based on the laser echo signal, and the optimal Gaussian component is determined based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates; finally, the altimetry positioning result is solved based on the optimal Gaussian component. In the satellite laser altimetry, the present invention flexibly selects Gaussian components by performing image segmentation on the footprint image to obtain a ground object segmentation image, and can effectively select the nearest Gaussian component of satellite laser altimetry under various complex terrains, effectively reducing the error of satellite laser altimetry. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 A schematic flow chart of an embodiment of the satellite laser altimetry positioning method under complex terrain provided by the present invention;

[0036] Figure 2 A real footprint image according to an embodiment of the present invention;

[0037] Figure 3 is a pixel brightness information image according to an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of a process for constructing a multi-component echo energy model according to an embodiment of the present invention;

[0039] Figure 5 Schematic diagram of a process for determining an optimal Gaussian component according to an embodiment of the present invention;

[0040] Figure 6 A schematic diagram of the information matching process according to an embodiment of the present invention;

[0041] Figure 7 A schematic diagram of the process of moving the laser foot point according to an embodiment of the present invention;

[0042] Figure 8 A schematic structural diagram of an embodiment of a satellite laser altimetry positioning device for complex terrain provided by the present invention;

[0043] Figure 9 This is a schematic structural diagram of an embodiment of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0044] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0045] In the description of the embodiments of the present invention, unless otherwise specified, "plurality" means two or more. "And / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone.

[0046] The terms "first" and "second" in the embodiments of the present invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, technical features designated as "first" or "second" may explicitly or implicitly include at least one such feature.

[0047] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0048] The present invention provides a satellite laser altimetry positioning method, device and electronic equipment under complex terrain, which are described below respectively.

[0049] Figure 1 The flowchart of an embodiment of the satellite laser altimetry positioning method under complex terrain provided by the present invention is as follows: Figure 1 As shown in FIG, the satellite laser altimetry positioning method under complex terrain includes:

[0050] S101, obtaining a footprint image of a laser foot point to be measured, a laser echo signal, and the coordinates of the corresponding image point of the laser foot point to be measured in the footprint image;

[0051] S102, performing image segmentation on the footprint image to obtain a ground object segmentation image, constructing a multi-component echo energy model based on the laser echo signal, and determining the optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates;

[0052] S103: Calculate the altimetry positioning result based on the optimal Gaussian component.

[0053] Compared with the prior art, the satellite laser altimetry positioning method under complex terrain provided by the embodiment of the present invention first obtains the footprint image of the laser footprint to be measured, the laser echo signal, and the corresponding image point coordinates of the laser footprint to be measured in the footprint image; then, the footprint image is segmented to obtain a ground object segmentation image, a multi-component echo energy model is constructed based on the laser echo signal, and the optimal Gaussian component is determined based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates; finally, the altimetry positioning result is solved based on the optimal Gaussian component. In the satellite laser altimetry, the present invention flexibly selects Gaussian components by performing image segmentation on the footprint image to obtain a ground object segmentation image, which can effectively select the nearest Gaussian component of satellite laser altimetry under various complex terrains, effectively reducing the error of satellite laser altimetry.

[0054] In some embodiments of the present invention, the multi-component echo energy model includes a plurality of echo components, the ground object segmentation image includes a plurality of segmentation sub-images, and the number of the echo components is equal to the number of the segmentation sub-images.

[0055] In some embodiments of the present invention, performing image segmentation on a footprint image to obtain a ground feature segmentation image includes:

[0056] The footprint image is segmented according to the pixel brightness information of the footprint image to obtain the ground feature segmentation image.

[0057] Specifically, Figure 2 This is a real footprint image according to an embodiment of the present invention. Figure 3 is the pixel brightness information image of the embodiment of the present invention. Figure 2 and Figure 3 As shown in the figure, during the satellite laser altimetry process, the ground objects in the satellite laser altimetry footprint reflect the sunlight after receiving the parallel light from the sun, and are finally received and imaged by the satellite laser altimetry footprint camera, as shown in the figure. Figure 2 Within the footprint range, the reflectivity of different types of objects (mainly considering the height feature in the embodiment) is different, and the pixel brightness information in the corresponding footprint image is also different, which can be obtained as follows: Figure 3 The corresponding pixel brightness information image. In the embodiment, image segmentation is performed by the brightness information of the pixels in the footprint image, so as to classify the different categories of ground objects in the image. During the image segmentation process, considering that the number of components obtained by waveform decomposition of the laser echo signal in the satellite laser altimetry can reflect the number of ground object features at different heights within the footprint range, the embodiment uses the echo components of the multi-component echo energy model as the number of image segmentation categories, and performs image segmentation on the footprint image according to the pixel brightness information of the footprint image to obtain a number of ground object segmentation images.

[0058] In some embodiments of the present invention, Figure 4 FIG. 1 is a flow chart of constructing a multi-component echo energy model according to an embodiment of the present invention. Figure 4 As shown in FIG, a multi-component echo energy model is constructed based on the laser echo signal, including:

[0059] S401, constructing a multi-component echo photon equation of the object to be measured according to the laser echo signal;

[0060] S402. Simplify the multi-component echo photon equation to obtain a multi-component echo energy model.

[0061] Specifically, in the embodiment, the laser emitted by the full-waveform satellite laser altimeter is transmitted through the atmosphere, reflected by the ground target, and passed through the atmosphere again to be received by the laser receiver. After processes such as photoelectric conversion and gain, the laser echo signal is finally sampled and recorded, and a multi-component echo energy model is established based on this.

[0062] After the noise filtering operation is completed on the full waveform echo of the satellite laser altimeter, the echo waveform can be considered as the superposition of multiple Gaussian signals, corresponding to the characteristic features at different elevations within the laser footprint, and the formula is expressed as:

[0063]

[0064] in, , and Respectively The amplitude, time centroid and RMS pulse width of each Gaussian component.

[0065] The number of photons contained in the return signal can be expressed as:

[0066]

[0067] in, is the laser detector gain, is the charge, is the voltage signal, is the transmitted pulse energy, is the photon energy, is the receiver aperture area, is the distance from the detector to the target, is the optical transmittance of the detector, Detector quantum efficiency, is the transmittance of laser in the atmosphere, is the target reflectivity, is the angle between the normal vector of the target reflecting surface and the field of view of the telescope.

[0068] in the formula The total number of photons contained in the echo pulse. The distribution of the number of photons at different times is the echo waveform of the laser. In the case of multi-component echo, there are characteristic distributions at different heights within the footprint, resulting in different return times for pulses emitted at the same time. The embodiment divides the terrain within the laser spot into grids or cells. , the laser reaches the surface element The propagation distance is expressed as , combined with the above formula, we can It is expressed as the sum of the number of echo photons for each bin (assuming that the noise in the echo has been removed):

[0069]

[0070] in, Detector to bin The distance from the center coordinates of To emit to the surface element The pulse energy can be expressed as:

[0071]

[0072] in, represents the root mean square of the laser emission energy distribution within the laser footprint, which is the laser footprint , For the surface element The plane position center coordinates, is the plane coordinate of the emitted laser vector direction within the footprint.

[0073] Simplifying the formula, it can be expressed as:

[0074]

[0075] in In the embodiment, the satellite laser altimeter divergence angle is about 40urad, the orbit altitude is 500-600km, and the footprint diameter is about 20m. Detector to bin The distance between the center coordinates of the footprint. Within the footprint range, different facets correspond to The difference is from several meters to tens of meters. The value itself is 500km level, different surface elements The difference in values ​​can be ignored, so the formula can be further simplified to:

[0076]

[0077] It can be seen that within the same footprint range, the integrated area of ​​a Gaussian component of the multi-echo component is equivalent to the product of the received pulse energy at the corresponding target, the reflectivity at the target, and the cosine of the scattering angle from the target to the detector field of view.

[0078] In some embodiments of the present invention, Figure 5 FIG. 1 is a flow chart of determining the optimal Gaussian component according to an embodiment of the present invention. Figure 5 As shown in FIG, the optimal Gaussian component is determined based on the ground object segmentation image, the multi-component echo energy model and the image point coordinates, including:

[0079] S501, performing information matching between the echo component and the segmentation sub-graph to obtain matching information;

[0080] S502: Determine the best Gaussian component according to the matching information and the image point coordinates.

[0081] In some embodiments of the present invention, Figure 6 Schematic diagram of the information matching process of an embodiment of the present invention, such as Figure 6 As shown, the echo component is matched with the segmentation sub-image to obtain matching information, including:

[0082] S601, determining the integrated area of ​​each echo component according to the multi-component echo energy model, and determining the pixel brightness value of each segmented sub-image according to the ground object segmentation image;

[0083] S602, sorting the integrated areas to obtain echo component sorting information, and sorting the pixel brightness values ​​to obtain segmentation sub-image sorting information;

[0084] S603: Match the echo component sorting information and the segmentation sub-graph sorting information to obtain matching information.

[0085] Specifically, based on the ground object segmentation image and multi-component echo energy model obtained in the previous steps, the embodiment can assume that the pixel brightness in the footprint image is equivalent to the product of the reflectivity of the corresponding ground object and the cosine of the scattering angle from the target to the detector field of view. The corresponding pixel brightness on the footprint image is ,common pixels, the multi-component echo energy model can be obtained:

[0086]

[0087] in, For the The plane position of pixels, For the The area corresponding to the pixel can be simplified as follows:

[0088]

[0089]

[0090]

[0091] Then, the embodiment can match the integral area of ​​the echo component with the pixel brightness and position information of the footprint image of the target area to determine the segmentation sub-images corresponding to different echo components. For example: suppose an echo has three echo components , the corresponding integral area is , the footprint image is segmented to obtain three segmentation sub-images in the ground feature segmentation image , the corresponding pixel brightness value is After sorting, if ,and , then match according to the sorting, the echo component Corresponding segmentation subgraph , echo component Corresponding segmentation subgraph , echo component Corresponding segmentation subgraph .

[0092] In the last embodiment, according to the segmented sub-graph where the coordinates of the corresponding image points of the laser height measurement foot points in the footprint image are located, the corresponding echo components are used as the best Gaussian components, and the height measurement positioning is solved based on this to obtain the height measurement positioning result.

[0093] In some embodiments of the present invention, Figure 7 FIG. 1 is a flow chart of moving the laser foot point according to an embodiment of the present invention. Figure 7 As shown, the satellite laser altimetry positioning method under complex terrain also includes:

[0094] S701: The sub-image corresponding to the pixel coordinates is used as the current sub-image. If the distance between the pixel coordinates and the adjacent sub-image of the current sub-image is less than a preset distance threshold or the difference in pixel brightness between the current sub-image and the adjacent sub-image of the current sub-image is less than a preset brightness threshold, the adjacent sub-image is used as a candidate sub-image.

[0095] S702, determining the surface characteristic parameters of the current sub-image and the surface characteristic parameters of the candidate sub-images according to the multi-component echo energy model;

[0096] S703: If the surface characteristic parameters of the current sub-image are smaller than the surface characteristic parameters of the candidate sub-image, the laser foot point to be measured is moved to the corresponding area of ​​the candidate sub-image, and the geodetic coordinates of the laser foot point to be measured after the movement are calculated.

[0097] Specifically, according to the above steps, the present invention provides a method for jointly determining the optimal Gaussian component corresponding to the laser ranging vector under multiple echo components using footprint images and echo waveform parameters, which can effectively improve the avoidance of errors in laser altimetry positioning. However, due to the influence of noise, thin clouds or fog that may be contained in the footprint image, image supervised classification may have certain errors, especially for pixels located in adjacent edge areas of different categories. At the same time, because the footprint camera's ground imaging band (400-800nm) is inconsistent with the laser altimetry measurement band (1064nm), the reflectivity information of the ground object indirectly expressed by the footprint image brightness information may be inconsistent with the reflectivity of the ground object in the laser measurement band, resulting in an incorrect match between the echo waveform decomposition components and the footprint image classification area.

[0098] To avoid the impact of these errors and provide more reliable laser footprint positioning coordinates, an embodiment of the present invention also includes a method for optimizing the laser footprint coordinates based on the footprint image information and the waveform characteristic parameters of the multi-component echo energy model. If the laser footprint landing position corresponds to the image point position in the footprint image and is located at the edge of two classification categories of the footprint image, or the brightness of different classification areas of the footprint image is relatively similar, the laser footprint positioning coordinates are moved to the corresponding area with smaller echo pulse width and larger amplitude. At this time, the Gaussian component with smaller echo pulse width and larger amplitude is used to calculate the laser ranging parameters. The specific process is as follows:

[0099] Assuming the number of echo components is 3, it can be expressed as , the segmentation sub-image of the footprint image is , the mutual matching relationship determined in the previous steps is , the image point in the image corresponding to the laser foot point is located at The edge part of the segmented sub-image area, and The segmented sub-image areas are adjacent;

[0100] According to the echo component parameters in the multi-component echo energy model , embodiment selection As the surface feature parameter of the segmented sub-image, it provides a reference for the movement of the laser foot point. Move the laser foot point to The area corresponding to the larger segmentation sub-graph. represents the amplitude of the echo component, Represents the pulse width of the echo component. The larger the Gaussian component amplitude and the smaller the pulse width, the flatter the corresponding surface feature and the stronger the reflectivity.

[0101] The Gaussian component and the selected surface characteristic parameters can be expressed as , and , the three components correspond to the segmentation subgraphs , and , the image point in the footprint image corresponding to the laser foot point is located at Within the category area, and with Category areas are adjacent, if , then move the laser foot point to Within the category area, the image point coordinates of the laser foot point in the footprint image are moved simultaneously (at the same time, the geodetic coordinate offset of the laser foot point is calculated according to the image point coordinate offset parameters and the footprint image external parameter parameters), and finally the echo component is selected. Used to calculate the distance from the satellite to the target in the direction of the laser ranging vector, and calculate the geodetic coordinates of the laser foot point after movement.

[0102] In order to verify the effectiveness of the embodiment of the present invention, the embodiment experimentally compares the scheme of the present invention with the prior art. The experimental area covers 50°21′N to 52°30′N, 6°E to 9°23′E, with an area of ​​approximately 34,080 square kilometers. The area contains a variety of landforms, such as plains, hills, mountains and canyons. The lowest altitude is -293 meters, the highest is 843.2 meters, and the average altitude is 109 meters. The experimental data includes Gaofen-7 laser altimetry data and high-precision airborne point cloud data. The average spatial resolution of the point cloud is 1m, and the plane and elevation accuracies are 0.5m and 0.2m respectively.

[0103] To verify the effectiveness and evaluate the accuracy of the satellite laser altimetry positioning method proposed in this invention for complex terrain, a comparative experiment compared four existing representative methods. Using different methods, we first selected the echo components used for ranging parameter calculation, then calculated the coordinates of the laser altimetry footpoints. Finally, we used a high-precision airborne point cloud to evaluate the elevation accuracy of the footpoints. For ease of comparison, the different component selection methods are labeled as follows:

[0104] The last Gaussian component - Last Gaussian (LastG);

[0105] The second-to-last Gaussian component - Penult Gaussian (PenultG);

[0106] Gaussian with maximum amplitude (MaxAmpG);

[0107] Gaussian with maximum area (MaxAreaG)

[0108] The satellite laser altimetry positioning method established in this program is Gaussian with graph cut and shift (GraphCutG_Shift).

[0109] Within the experimental area, the number of laser altimeter points with two, three, and four echo decomposition components was 52, 29, and 15, respectively. Of these, 46 were collected by the first laser and 50 by the second laser. To avoid verification errors caused by the time interval between the acquisition of the airborne laser point cloud and the laser altimeter data, this paper only evaluated the accuracy of the 65 laser altimeter points located in non-forested areas. The results are shown in Tables 1 and 2. Table 1 shows the elevation accuracy evaluation of footpoint positioning using the multi-echo component laser altimeter using the first laser, and Table 2 shows the elevation accuracy evaluation of footpoint positioning using the multi-echo component laser altimeter using the second laser.

[0110] Table 1

[0111]

[0112] Table 2

[0113]

[0114] Tables 1 and 2 show the evaluation results of the laser height measurement footpoint positioning elevation accuracy under the multiple echo components collected by laser 1 and laser 2 in the experimental area. It can be found that when the number of Gaussian components of the echo decomposition is 2 or 3, the laser distance measurement component determination and footpoint coordinate optimization method in the present invention has the best laser footpoint elevation accuracy, which is better than the existing typical method. However, when the number of components is 4, the accuracy of the method degrades.

[0115] However, it can also be found that in the experimental area, when the number of echo decomposition components is two, the maximum elevation error of the corresponding laser footprint positioning method in this paper still reaches 2.13m. After analyzing the terrain within the laser footprint and the laser footprint image, it was found that some areas within the footprint image were obscured by clouds and fog, resulting in errors in the classification of the laser footprint image ground features, and ultimately leading to the incorrect selection of the laser ranging component.

[0116] In summary, the present invention provides a method for satellite laser altimetry and positioning under complex terrain. First, the footprint image, laser echo signal, and corresponding image point coordinates of the laser footprint to be measured in the footprint image are obtained; then, the footprint image is segmented to obtain a ground object segmentation image, a multi-component echo energy model is constructed based on the laser echo signal, and the optimal Gaussian component is determined based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates; finally, the altimetry and positioning result is solved based on the optimal Gaussian component. In the satellite laser altimetry, the present invention flexibly selects Gaussian components by performing image segmentation on the footprint image to obtain a ground object segmentation image. This can effectively select the nearest Gaussian component for satellite laser altimetry under various complex terrains, effectively reducing the error of satellite laser altimetry.

[0117] In order to better implement the satellite laser altimetry positioning method under complex terrain in the embodiment of the present invention, based on the satellite laser altimetry positioning method under complex terrain, correspondingly, Figure 8 As shown, the present invention also provides a satellite laser altimeter positioning device under complex terrain. The satellite laser altimeter positioning device 800 under complex terrain includes:

[0118] The signal acquisition unit 801 is used to acquire the footprint image of the laser foot point to be measured, the laser echo signal and the coordinates of the corresponding image point of the laser foot point to be measured in the footprint image;

[0119] The optimal Gaussian component determination unit 802 is configured to perform image segmentation on the footprint image to obtain a ground object segmentation image, construct a multi-component echo energy model based on the laser echo signal, and determine the optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates;

[0120] The altimetry and positioning solving unit 803 is used to solve the altimetry and positioning result according to the optimal Gaussian component.

[0121] The satellite laser altimetry and positioning device 800 for complex terrain provided in the above embodiment can implement the technical solution described in the above embodiment of the satellite laser altimetry and positioning method for complex terrain. The specific implementation principles of the above modules or units can be found in the corresponding contents in the above embodiment of the satellite laser altimetry and positioning method for complex terrain, and will not be repeated here.

[0122] like Figure 9 As shown, the present invention also provides an electronic device 900. The electronic device 900 includes a processor 901, a memory 902 and a display 903. Figure 9 Only some of the components of the electronic device 900 are shown, but it should be understood that implementation of all of the shown components is not required, and more or fewer components may be implemented instead.

[0123] In some embodiments, the processor 901 can be a central processing unit (CPU), a microprocessor, or other data processing chip, used to run the program code or process data stored in the memory 902, such as the satellite laser altimetry positioning method under complex terrain in the present invention.

[0124] In some embodiments, the processor 901 may be a single server or a server group. The server group may be centralized or distributed. In some embodiments, the processor 901 may be local or remote. In some embodiments, the processor 901 may be implemented on a cloud platform. In one embodiment, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an internal cloud, multiple clouds, or any combination thereof.

[0125] In some embodiments, the memory 902 may be an internal storage unit of the electronic device 900, such as a hard disk or memory of the electronic device 900. In other embodiments, the memory 902 may also be an external storage device of the electronic device 900, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 900.

[0126] Furthermore, the memory 902 may include both an internal storage unit of the electronic device 900 and an external storage device. The memory 902 is used to store application software installed in the electronic device 900 and various data.

[0127] In some embodiments, the display 903 can be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. The display 903 is used to display information about the electronic device 900 and to display a visual user interface. Components 901-903 of the electronic device 900 communicate with each other via a system bus.

[0128] In one embodiment, when the processor 901 executes the satellite laser altimetry positioning program under complex terrain in the memory 902, the following steps may be implemented:

[0129] Obtaining a footprint image of the laser foot point to be measured, a laser echo signal, and the coordinates of the corresponding image point of the laser foot point to be measured in the footprint image;

[0130] Perform image segmentation on the footprint image to obtain a ground object segmentation image, construct a multi-component echo energy model based on the laser echo signal, and determine the optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates;

[0131] The altimetry positioning results are solved based on the optimal Gaussian component.

[0132] It should be understood that, when the processor 901 executes the satellite laser altimetry positioning program under complex terrain in the memory 902 , in addition to the above functions, it can also implement other functions. For details, please refer to the description of the corresponding method embodiment above.

[0133] Accordingly, an embodiment of the present application also provides a computer-readable storage medium, which is used to store computer-readable programs or instructions. When the program or instructions are executed by a processor, it can implement the steps or functions of the satellite laser altimetry positioning method under complex terrain provided by the above-mentioned method embodiments.

[0134] Those skilled in the art will appreciate that all or part of the process flow of the above-described method embodiment can be implemented by instructing related hardware (such as a processor, controller, etc.) through a computer program, and the computer program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0135] The above is a detailed introduction to the satellite laser altimetry positioning method, device, electronic device and storage medium under complex terrain provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A satellite laser altimetry positioning method under complex terrain, characterized in that: include: Acquire a footprint image of a laser foot point to be measured, a laser echo signal, and the coordinates of a corresponding image point of the laser foot point to be measured in the footprint image; Performing image segmentation on the footprint image to obtain a ground object segmentation image, constructing a multi-component echo energy model based on the laser echo signal, and determining an optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates; The altimetry positioning result is solved according to the optimal Gaussian component.

2. The satellite laser altimetry positioning method under complex terrain according to claim 1, characterized in that: The multi-component echo energy model includes a plurality of echo components, the ground object segmentation image includes a plurality of segmentation sub-images, and the number of the echo components is equal to the number of the segmentation sub-images.

3. The satellite laser altimetry positioning method under complex terrain according to claim 2, characterized in that: The step of performing image segmentation on the footprint image to obtain a ground object segmentation image includes: The footprint image is segmented according to the pixel brightness information of the footprint image to obtain a ground object segmentation image.

4. The satellite laser altimetry positioning method under complex terrain according to claim 2, characterized in that: The constructing of a multi-component echo energy model according to the laser echo signal comprises: Constructing a multi-component echo photon equation of the object to be measured according to the laser echo signal; The multi-component echo photon equation is simplified to obtain a multi-component echo energy model.

5. The satellite laser altimetry positioning method under complex terrain according to claim 1, characterized in that: The determining of the optimal Gaussian component according to the ground object segmentation image, the multi-component echo energy model and the image point coordinates includes: Matching the echo component with the segmentation sub-image to obtain matching information; An optimal Gaussian component is determined according to the matching information and the image point coordinates.

6. The satellite laser altimetry positioning method under complex terrain according to claim 5, characterized in that: The performing information matching between the echo component and the segmented sub-graph to obtain matching information includes: determining the integrated area of ​​each of the echo components according to the multi-component echo energy model, and determining the pixel brightness value of each of the segmented sub-images according to the ground object segmentation image; Sorting the integrated areas to obtain echo component sorting information, and sorting the pixel brightness values ​​to obtain segmentation sub-image sorting information; Matching information is performed on the echo component sorting information and the segmentation sub-image sorting information to obtain matching information.

7. The satellite laser altimetry positioning method under complex terrain according to claim 6, characterized in that: The method further comprises: The segmented sub-image corresponding to the pixel coordinates is used as the current sub-image. If the distance between the pixel coordinates and the adjacent sub-image of the current sub-image is less than a preset distance threshold or the difference in pixel brightness between the current sub-image and the adjacent sub-image of the current sub-image is less than a preset brightness threshold, the adjacent sub-image is used as a candidate sub-image. determining the surface characteristic parameters of the current sub-image and the surface characteristic parameters of the candidate sub-image according to the multi-component echo energy model; If the surface characteristic parameters of the current sub-image are smaller than the surface characteristic parameters of the candidate sub-image, the laser foot point to be measured is moved to the corresponding area of ​​the candidate sub-image, and the geodetic coordinates of the laser foot point to be measured after the movement are calculated.

8. A satellite laser altimetry positioning device for complex terrain, characterized in that: include: A signal acquisition unit, configured to acquire a footprint image of a laser foot point to be measured, a laser echo signal, and coordinates of a corresponding image point of the laser foot point to be measured in the footprint image; an optimal Gaussian component determination unit, configured to perform image segmentation on the footprint image to obtain a ground object segmentation image, construct a multi-component echo energy model based on the laser echo signal, and determine an optimal Gaussian component based on the ground object segmentation image, the multi-component echo energy model, and the image point coordinates; The altimetry and positioning solving unit is used to solve the altimetry and positioning result according to the optimal Gaussian component.

9. An electronic device comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the satellite laser altimetry positioning method under complex terrain according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the satellite laser altimetry positioning method under complex terrain according to any one of claims 1 to 7 is implemented.

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