Conservation tillage corn canopy BRDF model construction method and device

Abstract

The embodiment of the present invention provides a method and device for constructing a BRDF model of a corn canopy under conservation tillage. The method includes: constructing a three-dimensional model of a group of corn plants under conservation tillage mode according to three-dimensional point cloud information of corn plants under conservation tillage mode and color pictures of corn plants; establishing parameters of radiation transmission of corn leaves according to preset leaf physical and chemical property parameters and preset leaf structure information; and establishing a bidirectional reflectance distribution function model of a corn canopy under conservation tillage based on the three-dimensional model of the group of corn plants and the parameters of radiation transmission of the corn leaves. By making full use of the advantages of high precision of ground laser radar, a three-dimensional model of a group of corn plants under conservation tillage mode is constructed, and the spectral reflectance of the corn canopy under different width and narrow row planting modes and different observation angles is simulated through the DART discrete anisotropic three-dimensional radiation transmission model, filling the gap in the construction of a BRDF model of a corn canopy under conservation tillage.

Description

Technical Field

[0001] The present invention relates to the field of agricultural technology, and in particular to a method and a device for constructing a BRDF model of a conservation tillage corn canopy. Background Art

[0002] Conservation tillage refers to a sustainable agricultural technology that reduces soil erosion, protects the ecological environment of farmland, and achieves coordinated development of ecological, economic and social benefits through comprehensive supporting measures such as less tillage, no tillage, surface micro-topography transformation technology, surface covering, and reasonable planting. The core technologies of conservation tillage include less tillage, no tillage, equal-height tillage on gentle slopes, furrow and ridge tillage, straw covering, and wide and narrow row planting technology.

[0003] At present, narrow row planting technology has been promoted in most corn planting areas. The full name of narrow row planting technology is corn wide and narrow row alternating fallow planting technology, which is to change the current uniform ridge planting tillage method to a planting method with wide rows of 80-90cm and narrow rows of 40-50cm. Deep loosening is carried out in wide rows combined with topdressing before corn jointing. During autumn harvest, high stubble is left in narrow rows with seedling strips. After autumn harvest, wide rows are rotary tilled with strip tillers to achieve sowing state. The high stubble left in narrow rows naturally rots and returns to the field. In the spring of the second year, sowing is carried out in the rotary tilled wide rows to form new narrow row seedling strips. During the topdressing period, deep loosening and topdressing are carried out in the new wide rows, thus completing the wide and narrow row protective tillage mode of deep loosening, seedling strip rotation, and alternating fallow every other year.

[0004] Compared with the traditional uniform ridge planting method, the corn canopy of the wide and narrow row conservation tillage method is unevenly distributed, and this uneven canopy will bring more obvious angle effects when observed from different angles. However, the traditional vegetation canopy BRDF model does not take into account the canopy differences of this ridge structure.

[0005] Therefore, how to construct a BRDF model for the conservation tillage corn canopy has become an urgent problem to be solved in the industry. Summary of the invention

[0006] The embodiments of the present invention provide a method and device for constructing a BRDF model of a conservation tillage corn canopy, so as to solve the technical problems raised in the above-mentioned background technology, or at least partially solve the technical problems raised in the above-mentioned background technology.

[0007] In a first aspect, an embodiment of the present invention provides a method for constructing a conservation tillage corn canopy BRDF model, comprising:

[0008] Based on the 3D point cloud information of corn plants under conservation tillage mode and the color pictures of corn plants, a 3D model of corn plants under conservation tillage mode is constructed.

[0009] Establishing parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information;

[0010] Based on the three-dimensional model of the corn plant group and the parameters of the corn leaf radiation transmission, a conservation tillage corn canopy BRDF model is established.

[0011] More specifically, the step of constructing a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color picture of the corn plants specifically includes:

[0012] A plurality of discrete three-dimensional point clouds of corn plants under different width and narrow row conservation tillage modes are obtained by using various ground-based laser radar scanners, and the plurality of discrete three-dimensional point clouds of corn plants are spliced ​​according to the satellite positioning information of various ground-based laser radar scanners to obtain the three-dimensional point cloud information of the corn plants;

[0013] The three-dimensional point cloud information of the three-dimensional plant is merged with the color picture of the corn plant to obtain a three-dimensional color point cloud of the plant;

[0014] A three-dimensional model of a group of corn plants under a conservation tillage mode is constructed based on the three-dimensional plant color point cloud.

[0015] More specifically, the step of constructing a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional plant color point cloud specifically includes:

[0016] De-noising the three-dimensional plant color point cloud according to the point cloud density, and distinguishing the ground point cloud from the non-ground point cloud according to the point cloud color;

[0017] The non-ground point cloud is separated by using the Difference Of Normal (DON) method to obtain the corn leaf echo point cloud and the stalk echo point cloud;

[0018] Based on the corn leaf echo point cloud and the stalk echo point cloud, the three-dimensional modeling of the corn leaves and stalks is performed using the greedy surface triangulation method, and the surface is smoothed using the B-spline curve fitting method to obtain a three-dimensional model of a group of corn plants under the conservation tillage mode.

[0019] More specifically, the preset leaf physicochemical property parameters and preset leaf structure information include: anthocyanin content, mesophyll structure parameters, chlorophyll content, carotene content, brown pigment content, equivalent water thickness and specific leaf weight.

[0020] More specifically, the step of establishing the parameters of the radiation transmission of corn leaves according to the preset leaf physical and chemical property parameters and the preset leaf structure information specifically includes:

[0021] Inputting each preset leaf physical and chemical property parameter and preset leaf structure information into a preset leaf reflectivity model to obtain the reflectivity and transmittance of each corn leaf;

[0022] The parameters of corn leaf radiation transmission are established based on the reflectivity and transmittance of each corn leaf.

[0023] More specifically, the step of establishing a conservation tillage corn canopy BRDF model based on the three-dimensional model of the corn plant group and the parameters of the corn leaf radiation transmission specifically includes:

[0024] Based on the three-dimensional model of the corn plant group and the parameters of the corn leaf radiation transmission, the Discrete Anisotropic Radiative Transfer (DART) model was used to simulate the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting patterns, so as to establish a BRDF model of the corn canopy under conservation tillage.

[0025] In a second aspect, an embodiment of the present invention provides a device for constructing a BRDF model of a conservation tillage corn canopy, comprising:

[0026] A model building module is used to build a three-dimensional model of a group of corn plants under the conservation tillage mode based on the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color pictures of the corn plants;

[0027] A parameter building module is used to establish parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information;

[0028] The model building module is used to build a bidirectional reflectance distribution function (BRDF) model of the protective tillage corn canopy based on the three-dimensional model of the corn plant group and the parameters of the radiation transmission of the corn leaves.

[0029] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for constructing a conservation tillage corn canopy BRDF model as described in the first aspect are implemented.

[0030] In a fourth aspect, an embodiment of the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for constructing a conservation tillage corn canopy BRDF model as described in the first aspect.

[0031] The method and device for constructing a BRDF model of a conservation tillage corn canopy provided in an embodiment of the present invention fully utilize the high precision of ground laser radar to construct a three-dimensional model of a group of corn plants under a conservation tillage mode, and simulate the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting modes through the DART discrete anisotropic three-dimensional radiation transfer model, with reliable accuracy, filling the gap in the construction of a BRDF model of a conservation tillage corn canopy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 It is a schematic diagram of the process of constructing a BRDF model of a conservation tillage corn canopy described in one embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the internal action mechanism of a three-dimensional grid unit described in an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of a device for constructing a BRDF model of a corn canopy under conservation tillage as described in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of the structure of an electronic device described in one embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of 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.

[0038] Figure 1 FIG. 1 is a flow chart of a method for constructing a BRDF model of a corn canopy under conservation tillage as described in an embodiment of the present invention. Figure 1 As shown, including:

[0039] Step S1, constructing a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color picture of the corn plants;

[0040] Specifically, the three-dimensional point cloud information of corn plants described in the embodiment of the present invention refers to selecting different width and narrow row farming modes in a preset area, setting up multiple stations for each mode, acquiring corn canopy point cloud data by laser scanning, and stitching the point cloud data of multiple stations based on the GPS position of the center of the station.

[0041] The color picture of corn plants described in the embodiment of the present invention is a color image of corn plants in a conservation tillage mode taken by a camera.

[0042] For the massive point clouds after multi-station splicing, rough denoising is performed based on the point cloud density. Points with a density less than the specified threshold range are judged as noise points and removed to obtain the three-dimensional point cloud information of the corn plant. Then, the color image of the corn plant is fused with the three-dimensional point cloud information of the corn plant to obtain a three-dimensional plant color point cloud. In the fused three-dimensional plant color point cloud, the ground point cloud is brown and the corn plant point cloud is green. The ground point cloud and the non-ground point cloud are separated according to their color difference and the Z coordinate information of the point cloud. Then, the corn leaf echo point cloud and the stem echo point cloud are separated according to the normal direction, so that the three-dimensional modeling of the corn leaves and stems is performed through the greedy surface triangulation method, and the surface is smoothed using the B-spline curve fitting method to obtain a three-dimensional model of the group corn plants under the conservation tillage mode.

[0043] Step S2, establishing parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information;

[0044] The preset leaf physicochemical property parameters and preset leaf structure information described in the embodiments of the present invention specifically refer to anthocyanin content, mesophyll structure parameter N, chlorophyll a+b content, carotene content, brown pigment content, equivalent water thickness, and specific leaf weight.

[0045] In the PROSPECT model, it is assumed that the blade consists of N horizontal layers, and each layer is filled with air. Assume that a beam of light with a solid angle of Ω is incident on the blade at an angle α and then enters the air after multiple scattering. α and T α It represents the reflectivity and transmittance of leaves. After inputting the preset leaf physical and chemical properties parameters and the preset leaf structure information into the PROSPECT model, the leaf reflectivity and transmittance are output, thereby establishing the parameters of corn leaf radiation transmission.

[0046] Step S3, establishing a bidirectional reflectance distribution function (BRDF) model of the conservation tillage corn canopy based on the three-dimensional model of the corn plant group and the parameters of the corn leaf radiation transmission.

[0047] Specifically, based on the three-dimensional model of corn groups, the PROSPECT model at the leaf scale and the DART discrete anisotropic three-dimensional radiation transfer model at the canopy scale are used to simulate the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting patterns, thereby establishing a corn canopy BRDF model under different conservation tillage patterns.

[0048] The embodiment of the present invention fully utilizes the high precision of ground lidar to construct a three-dimensional model of a group of corn plants under the conservation tillage mode, and simulates the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting modes through the DART discrete anisotropic three-dimensional radiation transfer model, with reliable accuracy, filling the gap in the construction of the BRDF model of the conservation tillage corn canopy.

[0049] On the basis of the above embodiment, the step of constructing a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color picture of the corn plants specifically includes:

[0050] A plurality of discrete three-dimensional point clouds of corn plants under different width and narrow row conservation tillage modes are obtained by using various ground-based laser radar scanners, and the plurality of discrete three-dimensional point clouds of corn plants are spliced ​​according to the satellite positioning information of various ground-based laser radar scanners to obtain the three-dimensional point cloud information of the corn plants;

[0051] The three-dimensional point cloud information of the three-dimensional plant is merged with the color picture of the corn plant to obtain a three-dimensional color point cloud of the plant;

[0052] A three-dimensional model of a group of corn plants under a conservation tillage mode is constructed based on the three-dimensional plant color point cloud.

[0053] Specifically, the various ground-based laser radar scanners described in the embodiments of the present invention are distributed outside the corn plots and in the middle of the corn rows. Stations are arranged on both sides of typical wide and narrow rows. If necessary, corn plants outside the target area are cut off in the middle of the corn row where the visible range is small, and only the scanning target area is scanned with high precision. According to the principles of ensuring full coverage and a certain proportion of repeated scanning areas between adjacent stations, minimizing occlusion, easy selection of same-name points, and moderate scanning accuracy, the laser scanning scheme is determined, and 4-6 target balls are placed between the laser radars of adjacent stations as same-name points for point cloud data splicing. The target ball position selection follows the principles of full coverage as much as possible and distribution in the public area between the two scanning stations; set appropriate horizontal scanning resolution and vertical scanning resolution, and perform laser scanning on the selected stations in turn until the full coverage scan of the experimental area is completed.

[0054] Different width and narrow row tillage modes are selected in the preset area, and multiple stations are set up for each mode. Laser scanning is used to obtain corn canopy point cloud data. The point cloud data of multiple stations are spliced ​​based on the GPS position of the station center to obtain the three-dimensional point cloud information of the corn plant.

[0055] In the embodiment of the present invention, the three-dimensional plant point cloud information and the corn plant color picture are fused, and the ground is brown and the corn plant point cloud is green in the fused discrete color point cloud to obtain a three-dimensional plant color point cloud.

[0056] The step of constructing a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional plant color point cloud specifically includes:

[0057] De-noising the three-dimensional plant color point cloud according to the point cloud density, and distinguishing the ground point cloud from the non-ground point cloud according to the point cloud color;

[0058] The non-ground point cloud is separated by using the Difference Of Normal (DON) method to obtain the corn leaf echo point cloud and the stalk echo point cloud;

[0059] Firstly, the separated corn leaf and stalk echo point clouds were smoothed and resampled using the moving least squares (MLS) surface reconstruction method to further remove the noise data that was free from the leaf point cloud and the stalk point cloud, i.e., the precise denoising of the point cloud.

[0060] Then, the two-dimensional polygonal (concave or convex) boundary frames of the corn leaf and stalk are constructed respectively, each leaf is composed of one or more polygons, and the greater the curvature of the leaf, the more polygons need to be established;

[0061] Secondly, based on the constructed corn leaf and stalk polygons, the greedy surface triangulation method is used to perform 3D modeling of corn leaves and stalks. Triangulation is based on local points. The neighborhood is obtained by projecting the analyzed points along the normal direction. The parameters that need to be set include:

[0062] setmaximumNearestneighbors (unsigned) and setMu (double) to control the size of the neighborhood. The former defines how many neighbors are searched, and the latter specifies the maximum acceptable distance of a point to be considered relative to the nearest point. Typical values ​​are 50-100 and 2.5-3.

[0063] ·setSearchRadius(double integer), which is the maximum side length of each triangle.

[0064] ·setMinimumAngle(double integer) and setMaximumAngle(double integer) are the minimum and maximum angles of each triangle. Generally speaking, the minimum angle is difficult to guarantee, but the maximum angle can be guaranteed.

[0065] setMaximumSurfaceEagle (double integer) and setNormalConsistency (boolean) to handle situations where there are sharp angles and the two sides of the surface are very close. Points are not connected to the current point if their normals deviate more than the specified angle. If the normal consistency flag is not set, this angle is calculated as the angle between the lines defined by the normals, because not all normal estimation methods can guarantee consistent normal directions.

[0066] Finally, the constructed corn leaf and stalk triangles are smoothed using the B-spline curve fitting method to build a three-dimensional model of the corn plant in the entire scene. The specific fitting steps include:

[0067] Initialize the B-spline surface using principal component analysis (PCA);

[0068] Refine and fit B-spline surfaces;

[0069] Initialize the B-spline curve into a circle;

[0070] Triangulation of B-spline surfaces for pruning.

[0071] Finally, a three-dimensional model of a group of corn plants under the conservation tillage mode was obtained.

[0072] On the basis of the above-mentioned embodiment, the preset leaf physicochemical property parameters and preset leaf structure information include: anthocyanin content, mesophyll structure parameters, chlorophyll content, carotene content, brown pigment content, equivalent water thickness and specific leaf weight.

[0073] The step of establishing parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information specifically includes:

[0074] Inputting each preset leaf physical and chemical property parameter and preset leaf structure information into a preset leaf reflectivity model to obtain the reflectivity and transmittance of each corn leaf;

[0075] The parameters of corn leaf radiation transmission are established based on the reflectivity and transmittance of each corn leaf.

[0076] Specifically, the PROSPECT model at the leaf scale was used to establish a parameter scheme for radiative transfer in maize leaves.

[0077] In the parameterization scheme, the input parameters include anthocyanin content, leaf structure parameter N, chlorophyll a+b content, carotene content, brown pigment content, equivalent water thickness, specific leaf weight, G function Ω max ,Ω min , a, b weights, characterize the physical and chemical properties and structural conditions of the leaves; the output parameters include the reflectivity and transmittance of the leaves.

[0078] In the PROSPECT model, it is assumed that the blade consists of N horizontal layers, and each layer is filled with air. Assume that a beam of light with a solid angle of Ω is incident on the blade at an angle α and then enters the air after multiple scattering. α and T α Represents the reflectivity and transmittance of the blade, with R 90 and T 90 represents the reflectivity and transmittance of other horizontal layers except the first layer. For the blade, the relationship between the reflectivity and transmittance of N horizontal layers can be expressed as:

[0079]

[0080]

[0081] Among them, R α and T α The calculation formula is:

[0082]

[0083]

[0084] In the above formula, tav(α,n) is the transmittance of the medium surface.

[0085] Finally, based on the three-dimensional model of corn colony, the PROSPECT model at leaf scale and the DART discrete anisotropic three-dimensional radiation transfer model at canopy scale were used to simulate the spectral reflectance of corn canopy at different observation angles under different width and narrow row planting patterns, thereby establishing a corn canopy BRDF model under different conservation tillage patterns.

[0086] In the DART model, the analyzed scene is abstracted as a parallelepiped unit matrix. Each unit is regularly arranged along the Cartesian axes (x, y, z). The position of each unit is determined by the unit center position described by Cartesian coordinates. The length, width, and height of each unit are represented by Δx, Δy, and Δz respectively. The size of the scene in three dimensions is represented by ΔX, ΔY, and ΔZ. The total number of three-dimensional units in the scene is:

[0087] I=(ΔX·ΔY·ΔZ) / (Δx·Δy·Δz)

[0088] The three-dimensional scene of corn groups constructed in the present invention ignores the changes and influences of the terrain due to the small terrain undulations; the constructed scene focuses on the corn leaf unit, which is defined by the leaf direction, leaf inclination angle distribution, corn leaf body density and Lambertian optical properties / mirror properties.

[0089] Figure 2 Schematic diagram of the internal mechanism of a three-dimensional grid unit described in an embodiment of the present invention, as shown in FIG. Figure 2 As shown in Figure 2, in terms of the three-dimensional radiation transfer mechanism, in the DART discrete anisotropic three-dimensional radiation transfer model, the angular variable Ω is discretized into angular components Ω in N continuous discrete directions. n , which is used to distinguish the initial collision from multiple collisions. Assuming that the angular component is small enough and the medium is heterogeneous, the anisotropy of the scattered radiation is not strong. Then, in the Cartesian coordinate system, along Ω n Discrete angle radiation transfer equation for direction:

[0090]

[0091] Where W(r,Ω n ) is along Ω n Any angle ΔΩ in any direction n The flux at location parameter r.

[0092] The embodiment of the present invention fully utilizes the high precision of ground lidar to construct a three-dimensional model of a group of corn plants under the conservation tillage mode, and simulates the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting modes through the DART discrete anisotropic three-dimensional radiation transfer model, with reliable accuracy, filling the gap in the construction of the BRDF model of the conservation tillage corn canopy.

[0093] Figure 3 FIG. 1 is a schematic diagram of a device for constructing a BRDF model of a corn canopy under conservation tillage according to an embodiment of the present invention. Figure 3 As shown, it includes: a model construction module 310, a parameter construction module 320 and a model establishment module 330; wherein the model construction module 310 is used to construct a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color pictures of the corn plants; wherein the parameter construction module 320 is used to establish the parameters of the radiation transmission of the corn leaves according to the preset leaf physical and chemical properties parameters and the preset leaf structure information; wherein the model establishment module 330 is used to establish a bidirectional reflectance distribution function (Bidirectional Reflectance Distribution Function; BRDF) model of the conservation tillage corn canopy based on the three-dimensional model of the group of corn plants and the parameters of the radiation transmission of the corn leaves.

[0094] The device provided in the embodiment of the present invention is used to execute the above-mentioned method embodiments. Please refer to the above-mentioned embodiments for the specific process and detailed content, which will not be repeated here.

[0095] The embodiment of the present invention fully utilizes the high precision of ground lidar to construct a three-dimensional model of a group of corn plants under the conservation tillage mode, and simulates the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting modes through the DART discrete anisotropic three-dimensional radiation transfer model, with reliable accuracy, filling the gap in the construction of the BRDF model of the conservation tillage corn canopy.

[0096] Figure 4 FIG. 1 is a schematic diagram of the structure of an electronic device described in an embodiment of the present invention, such as Figure 4 As shown, the electronic device may include: a processor 410, a communication interface 420, a memory 430 and a communication bus 440, wherein the processor 410, the communication interface 420 and the memory 430 communicate with each other through the communication bus 440. The processor 410 may call the logic instructions in the memory 430 to execute the following method: construct a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color picture of the corn plants; establish parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information; and establish a bidirectional reflectance distribution function (BRDF) model of the conservation tillage corn canopy based on the three-dimensional model of the group of corn plants and the parameters of the corn leaf radiation transmission.

[0097] In addition, the logic instructions in the above-mentioned memory 430 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0098] An embodiment of the present invention discloses a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the methods provided by the above-mentioned method embodiments, for example, including: constructing a three-dimensional model of a group of corn plants under a conservation tillage mode based on three-dimensional point cloud information of corn plants and color pictures of corn plants under a conservation tillage mode; establishing parameters of corn leaf radiation transmission based on preset leaf physical and chemical property parameters and preset leaf structure information; and establishing a bidirectional reflectance distribution function (BRDF) model of a conservation tillage corn canopy based on the three-dimensional model of the group of corn plants and the parameters of the corn leaf radiation transmission.

[0099] An embodiment of the present invention provides a non-transitory computer-readable storage medium, which stores server instructions. The computer instructions enable a computer to execute the methods provided in the above embodiments, for example, including: constructing a three-dimensional model of a group of corn plants under a conservation tillage mode based on three-dimensional point cloud information of corn plants under a conservation tillage mode and color pictures of corn plants; establishing parameters for radiation transmission of corn leaves based on preset leaf physical and chemical properties parameters and preset leaf structure information; and establishing a bidirectional reflectance distribution function (Bidirectional Reflectance Distribution Function; BRDF) model of a conservation tillage corn canopy based on the three-dimensional model of the group of corn plants and the parameters for radiation transmission of the corn leaves.

[0100] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0101] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a BRDF model of a conservation tillage corn canopy, characterized in that: include: Based on the 3D point cloud information of corn plants under conservation tillage mode and the color pictures of corn plants, a 3D model of corn plants under conservation tillage mode was constructed; the conservation tillage mode was a wide-narrow row planting method with a wide row of 80-90 cm and a narrow row of 40-50 cm. Establishing parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information; Based on the three-dimensional model of the corn plant population and the parameters of the corn leaf radiation transmission, a bidirectional reflectance distribution function (BRDF) model of the corn canopy under conservation tillage is established; The step of establishing a conservation tillage corn canopy BRDF model based on the three-dimensional model of the corn plant group and the parameters of the corn leaf radiation transmission specifically includes: Based on the three-dimensional model of the corn plant group and the parameters of the corn leaf radiation transmission, the Discrete Anisotropic Radiative Transfer (DART) model was used to simulate the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting patterns, so as to establish a BRDF model of the corn canopy under conservation tillage.

2. The method for constructing a BRDF model of a conservation tillage corn canopy according to claim 1, characterized in that: The step of constructing a three-dimensional model of a group of corn plants under the conservation tillage mode according to the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color picture of the corn plants specifically includes: A plurality of discrete three-dimensional point clouds of corn plants under different width and narrow row conservation tillage modes are obtained by using various ground-based laser radar scanners, and the plurality of discrete three-dimensional point clouds of corn plants are spliced ​​according to the satellite positioning information of various ground-based laser radar scanners to obtain the three-dimensional point cloud information of the corn plants; The three-dimensional point cloud information of the corn plant is integrated with the color picture of the corn plant to obtain a color point cloud of the corn plant; A three-dimensional model of a group of corn plants under a conservation tillage mode is constructed based on the corn plant color point cloud.

3. The method for constructing a BRDF model of a conservation tillage corn canopy according to claim 2, characterized in that: The step of constructing a three-dimensional model of a group of corn plants under the conservation tillage mode according to the corn plant color point cloud specifically includes: De-noising the corn plant color point cloud according to the point cloud density, and distinguishing the ground point cloud from the non-ground point cloud according to the point cloud color; The non-ground point cloud is separated by using a difference of normal (DON) method to obtain a corn leaf echo point cloud and a stalk echo point cloud; Based on the corn leaf echo point cloud and the stalk echo point cloud, the three-dimensional modeling of the corn leaves and stalks is performed using the greedy surface triangulation method, and the surface is smoothed using the B-spline curve fitting method to obtain a three-dimensional model of a group of corn plants under the conservation tillage mode.

4. The method for constructing a BRDF model of a conservation tillage corn canopy according to claim 1, characterized in that: The preset leaf physicochemical property parameters and preset leaf structure information include: anthocyanin content, mesophyll structure parameters, chlorophyll content, carotene content, brown pigment content, equivalent water thickness and specific leaf weight.

5. The method for constructing a BRDF model for a conservation tillage corn canopy according to claim 4, characterized in that: The step of establishing parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information specifically includes: Inputting each preset leaf physical and chemical property parameter and preset leaf structure information into a preset leaf reflectivity model to obtain the reflectivity and transmittance of each corn leaf; The parameters of corn leaf radiation transmission are established based on the reflectivity and transmittance of each corn leaf.

6. A device for constructing a BRDF model of a corn canopy under conservation tillage, characterized in that: include: A model building module is used to build a three-dimensional model of a group of corn plants under the conservation tillage mode based on the three-dimensional point cloud information of the corn plants under the conservation tillage mode and the color pictures of the corn plants; wherein the conservation tillage mode is a wide-narrow row planting method with a wide row of 80-90 cm and a narrow row of 40-50 cm; A parameter building module is used to establish parameters of corn leaf radiation transmission according to preset leaf physical and chemical property parameters and preset leaf structure information; A model building module, used to build a bidirectional reflectance distribution function (BRDF) model of a conservation tillage corn canopy based on the three-dimensional model of the corn plant population and the parameters of the corn leaf radiation transmission; Wherein, the device is also used for: Based on the three-dimensional model of the corn plant group and the parameters of the corn leaf radiation transmission, the Discrete Anisotropic Radiative Transfer (DART) model was used to simulate the spectral reflectance of the corn canopy at different observation angles under different width and narrow row planting patterns, so as to establish a BRDF model of the corn canopy under conservation tillage.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method for constructing a conservation tillage corn canopy BRDF model as described in any one of claims 1 to 5 are implemented.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for constructing a conservation tillage corn canopy BRDF model as described in any one of claims 1 to 5 are implemented.

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