A method for calibrating all laser parameters of earth observation satellites taking into account terrain slope

Abstract

This invention discloses a method for calibrating all parameters of Earth observation satellite lasers, taking into account terrain slope, and relates to the field of on-orbit geometric calibration technology for spaceborne laser altimeters. This method optimizes traditional terrain matching methods, solving the problem that it can only calibrate the laser pointing of Earth observation satellites. By classifying the terrain slope of the laser landing point, laser points in flat slope areas [0, 5°) are used for laser ranging parameter calibration, while laser points in complex slope areas [5°, 60°) are used for laser pointing parameter calibration. Simultaneously, weighting is applied based on the saturation of inland objects at the laser point, reducing the impact of adverse factors on laser calibration accuracy and improving the efficiency of laser calibration. This patent can not only be used for calibration based on raw laser data but also improve the accuracy of Earth observation satellite laser altimeter products.

Description

Technical Field

[0001] The invention belongs to the technical field of on-orbit geometric calibration of satellite-borne laser altimeters, and in particular relates to a laser full-parameter calibration method for earth observation satellites taking terrain slope into consideration. Background Art

[0002] The successful implementation of the on-orbit geometric calibration test is one of the necessary conditions for the satellite-borne laser altimeter to obtain high-precision altimetry data. In the case of raw laser data, high-precision laser calibration parameters can be directly obtained by terrain matching or ground detector-based methods, and further laser altimetry data can be obtained; however, in some cases, only satellite laser altimetry products can be obtained.

[0003] Earth observation satellite lidar can be divided into linear satellite lidar and single-photon satellite lidar according to the working mode. In terms of laser, the linear system uses Nd:YAG (solid-state laser) and the single-photon system uses fiber laser; in terms of pulse wavelength, the linear system is mainly based on 1064nm wavelength, while the single-photon system uses the 532nm band with higher photon sensitivity; in terms of pulse repetition frequency, the single-photon system has a higher emission frequency, thus having a higher along-track resolution; in terms of elevation accuracy, the single-photon system has higher measurement accuracy than the linear system, which improves the ranging accuracy on steeper or rougher surfaces (such as cracks). In terms of application areas, the photon system lidar system has improved the technical capabilities of measuring vegetation height and statistically analyzing the status and changing patterns of vegetation biomass in large areas.

[0004] Laser rangefinder is a common payload for earth observation satellites. During the satellite launch process, it will produce multiple errors such as ranging, pointing angle, center of mass offset, system clock synchronization, etc., which affect the accuracy of laser ranging. The current experience of geometric calibration of satellite laser rangefinders at home and abroad can be divided into two categories: active and passive. Among them, active calibration methods include satellite laser geometric calibration based on ground active detectors and satellite laser geometric calibration based on airborne infrared camera imaging. Passive calibration methods include satellite laser geometric calibration based on satellite attitude maneuvers, satellite laser geometric calibration based on simulation waveform matching, and satellite laser geometric calibration based on natural surface matching.

[0005] By comparing the principles of calibration methods, we can see that active calibration is to calibrate the sensor by introducing a known reference signal or calibration object. This method can provide an accurate reference signal to achieve a high-precision calibration result, but active calibration usually requires the use of additional equipment or calibration objects, which may involve more costs and complexity. In addition, active calibration may be affected by environmental interference or equipment failure, so careful calibration and control are required. Passive calibration is to calibrate the sensor without introducing external signals or calibration objects. This method does not require additional equipment or calibration objects, and is usually calibrated by using the characteristics of the sensor itself or natural signals in the environment. Laser calibration based on terrain matching is a more commonly used method among passive calibration methods, but the method based on terrain matching still has many technical bottlenecks. Due to its low accuracy, it is currently only used as a rough calibration technology, and can only calibrate the laser pointing parameters, resulting in the calibration method being difficult to meet the needs of high-precision height measurement product production. Therefore, optimization research needs to be carried out on this method to improve the accuracy of laser height measurement. Summary of the invention

[0006] The purpose of the present invention is to provide a method for calibrating all parameters of an earth observation satellite laser taking into account the terrain slope, introduce a terrain slope factor, and be able to calibrate all parameter pointing and ranging or plane and elevation at the same time, providing a reliable means for satellite laser in-orbit calibration.

[0007] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0008] The present invention is a method for calibrating all parameters of a laser earth observation satellite taking into account the terrain slope, comprising the following steps:

[0009] Step 1: Batch input several pairs of input Earth observation satellite laser altimetry data (B i ,L i ,H i ), the laser altimetry data (B i ,L i ,H i ) is laser altimetry product data or laser raw data. If it is laser raw data, it is necessary to process the data to obtain corresponding laser altimetry product data;

[0010] Step 2: Calculate each laser height measurement data (B i ,L i ,H i ) corresponds to the terrain slope S i ;

[0011] Step 3: According to the terrain slope S i The laser altimetry data is classified and judged, and the slope in the interval [0,5°) is defined as the flat slope area Af The slope in [5°, 60°) is defined as the complex slope area A c , for terrain slope S i For areas that are not flat slopes A f and complex slope area A c The laser height measurement data is directly discarded and does not participate in the subsequent calibration process;

[0012] Step 4: For laser altimetry data with complex slopes, considering that the laser altimetry data itself may have positioning deviations, the ground object information around the laser altimetry data needs to be used as input to calculate the ground object saturation. Different ground object saturations are assigned corresponding weights Q. q ;

[0013] Step 5: The laser altimetry data of the flat slope and the weight Q are introduced q The laser height measurement data of complex slopes is brought into the laser full parameter solution formula for processing;

[0014] Step 6: Output the corresponding correction value according to the form of the input data. If the input is the original laser data, the output parameter after calibration is the laser pointing value. and ranging If the input is laser height measurement product data, the output parameter after calibration is the laser plane and elevation correction

[0015] As a preferred technical solution of the present invention, the step 1 further comprises:

[0016] Step 1.1: For the laser raw data, a rigorous satellite laser altimetry data processing geometric model is constructed and engineered into laser altimetry data processing software, and the laser raw data is processed using the software;

[0017] Step 1.2, for the laser altimetry data input or obtained after processing in step 1.1, the absolute value of the elevation difference δH of the public elevation data, the public elevation data should use the AW3D30 data of the global 30-meter grid. When δH>30 meters, the laser altimetry data is discarded, and the others are retained for subsequent calculations.

[0018] As a preferred technical solution of the present invention, in step 1.1, when constructing the laser altimetry data processing geometric model, the following formula is used:

[0019] Formula 1:

[0020]

[0021] Formula 2:

[0022]

[0023] Where:

[0024] ——Coordinates of the laser ground point in the Earth-fixed ground reference system ITRF;

[0025] ——Coordinates of the satellite's center of mass in the Earth-fixed ground reference system ITRF;

[0026] ——Space-fixed inertial reference system ICRF to Earth-fixed terrestrial reference system ITRF;

[0027] ——Transformation matrix from satellite body coordinate system BOD to space fixed inertial reference system ICRF;

[0028] ——The fixed offset between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0029] ——The offset change between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0030] ρ0——is the laser ranging value, measured by the laser ranging unit;

[0031] dρ atm ——atmospheric correction value;

[0032] α——The angle between the projection of the laser light-emitting axis on the XOY plane of the body coordinate system and the positive direction of the X axis;

[0033] β——The angle between the laser light output axis and its projection line on the XOY plane.

[0034] ——Laser altimetry data in latitude and longitude format;

[0035] ——Convert the laser point coordinates in the earth fixed coordinate system into the laser point coordinates in the longitude and latitude coordinate system;

[0036] dρ tides ——Tidal correction value.

[0037] As a preferred technical solution of the present invention, in step 2, the calculation formula of the slope is as follows:

[0038]

[0039] In the formula, R laser Indicates the ground diameter of the laser spot, E calrepresents the ground positioning error of the laser spot, H high and H low Represents laser altimetry data (B i ,L i ,H i ) near the maximum and minimum elevations.

[0040] As a preferred technical solution of the present invention, in step 4,

[0041] Ground saturation Sat q Using the three-dimensional surface area S3D q and the surface projection area S2D q The ratio is calculated as follows:

[0042]

[0043] Different ground feature saturations are assigned corresponding weights using the following formula:

[0044]

[0045] As a preferred technical solution of the present invention, the following steps are also included

[0046] Step 7: If the input in step 1 is laser raw data, it is necessary to comprehensively consider the relative position offset and rotation geometric relationship of the satellite platform center of mass, laser emission position, GPS antenna and earth ellipsoid, build a rigorous geometric calibration model of satellite-borne laser altimeter, and calibrate the laser raw data. The matrix form is shown in the formula:

[0047] Formula 1

[0048]

[0049] Formula 2

[0050]

[0051] Where:

[0052] ——Coordinates of the laser ground point in the earth-fixed coordinate system ITRF;

[0053] ——Coordinates of the satellite's center of mass in the Earth-fixed coordinate system ITRF;

[0054] ——Transformation matrix from satellite body coordinate system BOD to earth inertial coordinate system ICRF;

[0055] ——Transformation matrix from the Earth inertial coordinate system ICRF to the Earth fixed coordinate system ITRF;

[0056] ——The fixed offset between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0057] ——The offset change between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0058] ρ0——Laser ranging parameter, measured by the laser ranging unit;

[0059] dρ atm ——atmospheric correction value;

[0060] Δd——Laser ranging calibration parameter;

[0061] α——One of the laser pointing parameters, the angle between the projection of the laser light axis on the XOY plane of the body coordinate system and the positive direction of the X axis;

[0062] β——One of the laser pointing parameters, the angle between the laser light axis and its projection line on the XOY plane;

[0063] Δα, Δβ——laser pointing calibration parameters;

[0064] ——Laser ground point coordinates in longitude and latitude format;

[0065] ——Convert the laser point coordinates in the earth fixed coordinate system into the laser point coordinates in the longitude and latitude coordinate system;

[0066] dρ tides ——Tidal correction value.

[0067] As a preferred technical solution of the present invention, it also includes step 7. If the input is laser height measurement product data, it is necessary to add the laser measurement value to the laser plane. and elevation correction The laser height measurement product data is calibrated and the matrix form is shown in the formula:

[0068] Formula 1

[0069]

[0070] Where:

[0071] ——The coordinates of the terrain data corresponding to the laser altimetry product in the earth fixed coordinate system ITRF (in longitude and latitude format);

[0072] ——Coordinates of laser altimetry products in the earth-fixed coordinate system IITRF.

[0073] The present invention has the following beneficial effects:

[0074] The beneficial effects brought by the present invention are mainly reflected in the following aspects:

[0075] 1. Improve laser calibration accuracy: By classifying the terrain slope of the laser landing point, the present invention can more accurately calibrate the laser ranging parameters and pointing parameters of the earth observation satellite. The laser points in the flat slope area are used for laser ranging parameter calibration, while the laser points in the complex slope area are used for laser pointing parameter calibration. This targeted classification processing method effectively reduces the impact of adverse factors on the laser calibration accuracy.

[0076] 2. Improve the efficiency of laser calibration: This invention not only optimizes the traditional terrain matching method and solves the problem of only being able to calibrate the laser pointing of earth observation satellites, but also further improves the efficiency of laser calibration by weighting the laser points according to the saturation of the objects within the laser points. This comprehensive processing method makes the laser calibration process more efficient and accurate.

[0077] 3. Expand the scope of application: The beneficial effects of the present invention are not limited to calibration based on raw laser data, but can also be applied to improve the accuracy of satellite laser altimetry products for earth observation. Even if only satellite laser altimetry products can be obtained in some cases, this patent can still use terrain data to solve the problem of improving the accuracy of satellite laser altimetry products.

[0078] 4. Promote the development of satellite-borne laser altimeter technology: The proposal and implementation of this invention has a positive role in promoting the development of on-orbit geometry calibration of satellite-borne laser altimeters. By improving the accuracy and efficiency of laser calibration, this invention helps to promote the development of satellite-borne laser altimeter technology towards higher accuracy and wider application fields.

[0079] In summary, the beneficial effects of the present invention are mainly reflected in improving the accuracy of laser calibration, enhancing the efficiency of laser calibration, expanding the scope of application, and promoting the development of satellite-borne laser altimetry technology, etc. These beneficial effects are of great significance for promoting technological progress and application expansion in related fields.

[0080] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0082] Figure 1 It is a schematic diagram of the process of the present invention; DETAILED DESCRIPTION

[0083] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. According to the embodiments of the present invention, satellite-borne laser altimetry data can be randomly sampled for calibration; preferably, a specific application of this embodiment is to take the full-parameter calibration of the laser altimetry of the Gaofen-7 satellite as an example, but it is not limited to this.

[0084] See also Figure 1 As shown, the present invention is a method for calibrating all parameters of a laser for an earth observation satellite taking into account the terrain slope, comprising the following steps:

[0085] Step 1: Batch input of no less than 30 Earth observation satellite laser altimetry data (B i ,L i ,H i ), the laser altimetry data (B i ,L i ,H i ) is laser altimetry product data or laser raw data, B represents the geodetic latitude of the laser altimetry data, L represents the geodetic longitude of the laser altimetry data, H represents the geodetic height of the laser altimetry data, i represents the sequence number of the laser altimetry data, i=1,2,3,…,n, n represents the total number of laser altimetry data. If it is laser raw data, it is necessary to process the data to obtain the corresponding laser altimetry product data.

[0086] Step 1.1: If it is raw laser data, it is necessary to use a rigorous satellite laser altimetry data processing geometric model to process it into a laser altimetry product.

[0087] When constructing the geometric model for laser altimetry data processing, the following formula is used:

[0088] Formula 1:

[0089]

[0090] Formula 2:

[0091]

[0092] Where:

[0093] ——Coordinates of the laser ground point in the Earth-fixed ground reference system ITRF;

[0094] ——Coordinates of the satellite's center of mass in the Earth-fixed ground reference system ITRF;

[0095] ——Space-fixed inertial reference system ICRF to Earth-fixed terrestrial reference system ITRF;

[0096] ——Transformation matrix from satellite body coordinate system BOD to space fixed inertial reference system ICRF;

[0097] ——The fixed offset between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0098] ——The offset change between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0099] ρ0——is the laser ranging value, measured by the laser ranging unit;

[0100] dρ atm ——atmospheric correction value;

[0101] α——The angle between the projection of the laser light-emitting axis on the XOY plane of the body coordinate system and the positive direction of the X axis;

[0102] β——The angle between the laser light output axis and its projection line on the XOY plane.

[0103] ——Laser altimetry data in latitude and longitude format;

[0104] ——Convert the laser point coordinates in the earth fixed coordinate system into the laser point coordinates in the longitude and latitude coordinate system;

[0105] dρ tides ——tidal correction value;

[0106] Step 1.2, calculate the absolute value of the elevation difference δH between the processed laser altimeter data and the public elevation data. The public elevation data should use the AW3D30 data of the global 30-meter grid. When δH>30 meters, discard the laser altimeter data, and retain the others for subsequent calculations.

[0107] Step 2: Calculate each laser height measurement data (B i ,L i ,H i ) corresponds to the terrain slope S i , slope S i The calculation formula is as follows:

[0108]

[0109] In the formula, R laser Indicates the ground diameter of the laser spot, E cal represents the ground positioning error of the laser spot, H high and H low Represents laser altimetry data (B i ,L i ,H i ) near the maximum and minimum elevations.

[0110] Step 3: According to the terrain slope S i Laser altimetry data (B i ,L i ,H i ) is classified, and the slope [0,5°) is defined as the flat slope area A f , the laser point in this area is marked as (B p ,L p ,H p ), p represents the serial number of laser height measurement data, p=1,2,3,…,p all ,p all Indicates the flat slope area A f The total number of laser altimetry data in the complex slope area A is defined as the slope of [5°, 60°) c , the laser point in this area is marked as (B q ,L q ,H q ), q represents the serial number of the laser height measurement data, q=1,2,3,…,q all ,q all Indicates complex slope area A c The total number of laser altimetry data in the terrain slope S i For areas that are not flat slopes A f and complex slope area A c The laser altimetry data is directly discarded and does not participate in the subsequent calibration process.

[0111] Step 4: Laser altimetry data for complex slopes (B q ,L q ,H q), considering that the laser altimetry data itself may have positioning deviation, it is necessary to take the ground object information around the laser altimetry data as input to calculate the ground object saturation, and assign corresponding weights Q to different ground object saturations q , specific ground feature saturation Sat q Using the three-dimensional surface area S3D q and the surface projection area S2D q The ratio is calculated as follows:

[0112]

[0113] Different ground feature saturations are assigned corresponding weights using the following formula:

[0114]

[0115] Step 5: Convert the laser height measurement data of the flat slope (B p ,L p ,H p ) and laser altimetry data of complex slopes (B q ,L q ,H q ) is introduced into the laser full parameter solution formula. The laser height measurement data of complex slopes needs to introduce the weight Q q .

[0116] Step 6: Output the corresponding correction value according to the form of the input data. If the input is the original laser data, the output parameter after calibration is the laser pointing value. and ranging If the input is laser height measurement product data, the output parameter after calibration is the laser plane and elevation correction These correction values ​​can be used to improve the accuracy and reliability of laser altimetry data and provide more accurate data support for subsequent applications.

[0117] Step 6.1 If the input in step 1 is laser raw data, it is necessary to comprehensively consider the relative position offset and rotation geometric relationship of the satellite platform center of mass, laser emission position, GPS antenna and earth ellipsoid, build a rigorous geometric calibration model of satellite-borne laser altimeter, and calibrate the laser raw data. The matrix form is shown in the formula:

[0118] Formula 1

[0119]

[0120] Formula 2

[0121]

[0122] Where:

[0123] ——Coordinates of the laser ground point in the earth-fixed coordinate system ITRF;

[0124] ——Coordinates of the satellite's center of mass in the Earth-fixed coordinate system ITRF;

[0125] ——Transformation matrix from satellite body coordinate system BOD to earth inertial coordinate system ICRF;

[0126] ——Transformation matrix from the Earth inertial coordinate system ICRF to the Earth fixed coordinate system ITRF;

[0127] ——The fixed offset between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0128] ——The offset change between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD;

[0129] ρ0——Laser ranging parameter, measured by the laser ranging unit;

[0130] dρ atm ——atmospheric correction value;

[0131] Δd——Laser ranging calibration parameter;

[0132] α——One of the laser pointing parameters, the angle between the projection of the laser light axis on the XOY plane of the body coordinate system and the positive direction of the X axis;

[0133] β——One of the laser pointing parameters, the angle between the laser light axis and its projection line on the XOY plane;

[0134] Δα, Δβ——laser pointing calibration parameters;

[0135] ——Laser ground point coordinates in longitude and latitude format;

[0136] ——Convert the laser point coordinates in the earth fixed coordinate system into the laser point coordinates in the longitude and latitude coordinate system;

[0137] dρ tides ——Tidal correction value.

[0138] Step 6.2: If the input is laser height measurement product data, you need to add the laser measurement value to the laser plane. and elevation correction The laser height measurement product data is calibrated and the matrix form is shown in the formula:

[0139] Formula 1

[0140]

[0141] Where:

[0142] ——The coordinates (in longitude and latitude format) of the terrain data corresponding to the laser altimetry product in the earth fixed coordinate system IITRF;

[0143] ——Coordinates of laser altimetry products in the earth-fixed coordinate system ITRF.

[0144] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0145] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for calibrating all parameters of a laser earth observation satellite taking into account terrain slope, characterized in that: The following steps are involved: Step 1: Batch input of laser altimetry data from several Earth observation satellites (B i ,L i ,H i ), the laser altimetry data (B i ,L i ,H i ) is laser altimetry product data or laser raw data. If it is laser raw data, it is necessary to process the data to obtain corresponding laser altimetry product data; Step 2: Calculate each laser height measurement data (B i ,L i ,H i ) corresponds to the terrain slope S i ; Step 3: According to the terrain slope S i The laser altimetry data is classified and judged, and the slope in the interval [0,5°) is defined as the flat slope area A f The slope in [5°, 60°) is defined as the complex slope area A c , for terrain slope S i For areas that are not flat slopes A f and complex slope area A c The laser height measurement data is directly discarded and does not participate in the subsequent calibration process; Step 4: For laser altimetry data with complex slopes, the ground object information around the laser altimetry data is used as input to calculate the ground object saturation. Different ground object saturations are assigned corresponding weights Q q ; Step 5: The laser altimetry data of the flat slope and the weight Q are introduced q The laser height measurement data of complex slopes is brought into the laser full parameter solution formula for processing; Step 6: Output the corresponding correction value according to the form of the input data. If the input is the original laser data, the output parameter after calibration is the laser pointing value. and ranging If the input is laser height measurement product data, the output parameter after calibration is the laser plane and elevation correction 2. The method for calibrating all parameters of a laser earth observation satellite taking into account terrain slope according to claim 1, characterized in that: The step 1 also includes: Step 1.1: For the laser raw data, a rigorous satellite laser altimetry data processing geometric model is constructed and engineered into laser altimetry data processing software, and the laser raw data is processed using the software; Step 1.2, for the laser altimetry data input or obtained after processing in step 1.1, the absolute value of the elevation difference δH of the public elevation data, the public elevation data uses the AW3D30 data of the global 30-meter grid. When δH>30 meters, the laser altimetry data is discarded, and the others are retained for subsequent calculations.

3. The method for calibrating all parameters of a laser earth observation satellite taking into account terrain slope according to claim 2, characterized in that: In step 1.1, the following formula is used to construct the laser altimetry data processing geometric model: Formula 1: Formula 2: Where: ——Coordinates of the laser ground point in the Earth-fixed ground reference system ITRF; ——Coordinates of the satellite's center of mass in the Earth-fixed ground reference system ITRF; ——Space-fixed inertial reference system ICRF to Earth-fixed terrestrial reference system ITRF; ——Transformation matrix from satellite body coordinate system BOD to space fixed inertial reference system ICRF; ——The fixed offset between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD; ——The offset change between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD; ρ0——is the laser ranging value, measured by the laser ranging unit; dρ atm ——atmospheric correction value; α——The angle between the projection of the laser light-emitting axis on the XOY plane of the body coordinate system and the positive direction of the X axis; β——The angle between the laser light axis and its projection line on the XOY plane; ——Laser altimetry data in latitude and longitude format; ——Convert the laser point coordinates in the earth fixed coordinate system into the laser point coordinates in the longitude and latitude coordinate system; dρ tides ——Tidal correction value.

4. The method for calibrating all parameters of a laser earth observation satellite taking into account terrain slope according to claim 1, characterized in that: In step 2, the slope is calculated as follows: In the formula, R laser Indicates the ground diameter of the laser spot, E cal Represents the ground positioning error of the laser spot, H high and H low Represents laser altimetry data (B i ,L i ,H i ) near the maximum and minimum elevations.

5. The method for calibrating all parameters of a laser earth observation satellite taking into account terrain slope according to claim 1, characterized in that: In step 4, Ground saturation Sat q Using the three-dimensional surface area S3D q and the surface projection area S2D q The ratio is calculated as follows: Different ground feature saturations are assigned corresponding weights using the following formula:

6. The method for calibrating all parameters of a laser earth observation satellite taking into account terrain slope according to claim 1, characterized in that: The following steps are also included: Step 7: If the input in step 1 is laser raw data, it is necessary to comprehensively consider the relative position offset and rotation geometric relationship of the satellite platform center of mass, laser emission position, GPS antenna and earth ellipsoid, build a rigorous geometric calibration model of satellite-borne laser altimeter, and calibrate the laser raw data. The matrix form is shown in the formula: Formula 1 Formula 2 Where: ——Coordinates of the laser ground point in the earth-fixed coordinate system ITRF; ——Coordinates of the satellite's center of mass in the Earth-fixed coordinate system ITRF; ——Transformation matrix from satellite body coordinate system BOD to earth inertial coordinate system ICRF; ——Transformation matrix from the Earth inertial coordinate system ICRF to the Earth fixed coordinate system ITRF; ——The fixed offset between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD; ——The offset change between the laser emission reference point and the satellite mass center in the satellite body coordinate system BOD; ρ0——Laser ranging parameter, measured by the laser ranging unit; dρ atm ——atmospheric correction value; Δd——Laser ranging calibration parameter; α——One of the laser pointing parameters, the angle between the projection of the laser light axis on the XOY plane of the body coordinate system and the positive direction of the X axis; β——One of the laser pointing parameters, the angle between the laser light axis and its projection line on the XOY plane; Δα, Δβ——laser pointing calibration parameters; ——Laser ground point coordinates in longitude and latitude format; ——Convert the laser point coordinates in the earth fixed coordinate system into the laser point coordinates in the longitude and latitude coordinate system; dρ tides ——Tidal correction value.

7. The method for calibrating all parameters of a laser earth observation satellite taking into account terrain slope according to claim 1, characterized in that: Step 7 is also included. If the input is laser height measurement product data, the laser measurement value needs to be added to the laser plane. and elevation correction The laser height measurement product data is calibrated and the matrix form is shown in the formula: Formula 1 Where: ——The coordinates of the terrain data corresponding to the laser altimetry product in the earth fixed coordinate system ITRF; ——Coordinates of laser altimetry products in the earth-fixed coordinate system ITRF.

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