Calculation method of GM-APD lidar echo energy based on improved core brdf model

A technology of lidar and calculation method, applied in radio wave measurement systems, instruments, etc., can solve the problems of not considering the daytime background light scattering model, poor guidance of daytime target detection strategies, etc.

Active Publication Date: 2022-03-22
HARBIN INST OF TECH
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Problems solved by technology

At present, the lidar equation does not consider the daytime background light scattering model, especially for detectors such as Gm-APD that are susceptible to background light interference, there is an urgent need to establish a lidar echo noise model
In fact, the echo noise is closely related to the scattering characteristics of the target. At present, no connection between the noise model and the scattering characteristics of the target is used in the research of daytime Gm-APD detection theory. Usually, the noise is set to a fixed value during the application process. , poor guidance for daytime target detection strategy

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  • Calculation method of GM-APD lidar echo energy based on improved core brdf model
  • Calculation method of GM-APD lidar echo energy based on improved core brdf model
  • Calculation method of GM-APD lidar echo energy based on improved core brdf model

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specific Embodiment 1

[0053] The present invention provides a kind of Gm-APD lidar echo energy calculation method based on the BRDF model of improved core, comprising the following steps:

[0054] Step 1: Establish a background light model to obtain the background light. When the scattered light in the hemispherical space is mixed with the incident light intensity, a BRDF model of the background light is established;

[0055] Step 2: According to the actual reflection mechanism of the target, establish a BRDF model corresponding to the laser;

[0056] Step 3: Improve the existing BRDF model, convert the BRDF model into a time function within the lidar gating range, and use the background light equivalent intensity coefficient to establish a laser-background noise relationship function;

[0057] Step 4: Use the background equivalent intensity coefficient to establish a relationship between the laser and the background noise, so that the expression of the lidar equation is more perfect. The lidar equ...

specific Embodiment 2

[0060] 1. Theoretical model of background light

[0061] In the application of lidar, the background light is considered to be constant in theory. In fact, the background light is closely related to the sun position, background environment, target attitude, etc. There are many sources of background light in the actual scene, but it can be simplified into two parts. See formula (1):

[0062] L=L dir +L diff (1)

[0063] In the formula, L is the background light, Ldir is the sunlight directly reflected by the target, and then transmitted through the atmosphere and received by the detector, and Ldiff is the light intensity directly received by the detector after the diffuse scattered light of the atmosphere is reflected by the target .

[0064] When the diffuse scattered light in the hemispherical space is mixed in the entire incident light intensity, the BRDF model of the background light can be expressed as:

[0065]

[0066] In the formula, θ s is the zenith angle of...

specific Embodiment 3

[0091] The trigger characteristics of a single pixel of area array imaging lidar are studied, assuming that the target corresponding to the pixel is a planar structure. Parameters of the lidar system: η 1 = η 2=0.9, receiving aperture D=80mm, area array Gm-APD resolution of 128×128, detector duty cycle of 0.1, laser single pulse emission energy of 1mJ, single photon detection probability of 15%, laser wavelength of 1.06μm, The laser radar filter bandwidth is 10nm, the laser emitting and receiving field of view is 2°, the atmospheric visibility is 20km, and the laser spots are evenly distributed. The length of the gate is 1 μs, the number of Δτ in the gate is 1000, and the echo pulse occupies at most one time interval, and the echo pulse is in the middle of the gate.

[0092] figure 1 It shows the change of the echo trigger probability with the detection angle when the normal direction of the target observation surface is due south and the target is at different distances at...

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Abstract

The present invention is based on the Gm-APD laser radar echo energy calculation method of the improved core BRDF model. The present invention adopts the establishment idea of ​​the kernel-based BRDF model, takes LL-BRDF as the core, considers the source of background light and echo light, and establishes an improved kernel-based BRDF model suitable for Gm-APD laser radar for the first time, and the model uses the background, etc. The background light and the laser echo are connected by the effective intensity coefficient, and the mixed scattered light model is obtained, so that the BRDF model can describe the actual target scattering situation more accurately. The laser radar equation model built in this patent can more clearly describe the composition and distribution characteristics of the echo. Compared with the existing laser radar equation, it is more in line with the actual physical laws, and the equation can simultaneously obtain noise light and laser echo light. Quantitative research provides stronger support.

Description

technical field [0001] The invention relates to the technical field of Gm-APD laser radar echo energy calculation, and relates to a Gm-APD laser radar echo energy calculation method based on an improved core BRDF model. Background technique [0002] At present, the research on the trigger characteristics of Gm-APD seldom considers the influence of the actual target scattering characteristics on the target detection probability and range, because the target scattering model used is only a simple Lambertian scattering model, which is different from the actual target scattering model. Properties do not match. As early as 2000, some researchers introduced the Bidirectional Reflectance Distribution Function (BRDF), which can describe the target scattering characteristics, into the lidar equation, but it has not been used to solve the trigger probability problem caused by Gm-APD target scattering. At present, the lidar equation does not consider the daytime background light scatt...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01S7/48
CPCG01S7/4802
Inventor 孙剑峰周鑫刘迪王海虹陆威李思宁
Owner HARBIN INST OF TECH
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