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Crop radar signal incident angle normalization method based on NDVI

A radar signal, normalization technology, applied in the direction of electromagnetic wave re-radiation, utilization of re-radiation, complex mathematical operations, etc., can solve the problem that the cosine normalization method can not meet the normalization requirements of the radar incident angle

Pending Publication Date: 2021-12-07
NORTHEAST INST OF GEOGRAPHY & AGRIECOLOGY C A S
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problem in the prior art that the cosine normalization method cannot meet the normalization requirements of radar incident angles of different crops at different growth stages, and to provide a NDVI-based crop radar signal incident angle normalization method

Method used

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  • Crop radar signal incident angle normalization method based on NDVI
  • Crop radar signal incident angle normalization method based on NDVI
  • Crop radar signal incident angle normalization method based on NDVI

Examples

Experimental program
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Effect test

Embodiment 1

[0062] Step 1. Collect the latitude and longitude coordinate information of corn crops in Heilongjiang Province, such as figure 1 As shown, there are 1457 corn sampling points;

[0063] Step 2. According to the latitude and longitude coordinates, obtain the Sentinel-1 ( Angle) and Sentinel-2 data (Band4-Red, Band8-NIR);

[0064] Step 3. Calculate the normalized difference vegetation index NDVI according to the obtained Red data and NIR data of each recording point. The calculation formula is as follows:

[0065] NDVI=(NIR-RED) / (NIR+RED)

[0066] Perform S-G filtering on the calculated NDVI to generate NDVI data matching the Sentinel-1 date;

[0067] Will The Angle data is substituted into the cosine normalization method, and the N value in the cosine normalization method is solved by least square fitting, and then the N value of each recording point is obtained;

[0068] The calculation formula of the cosine normalization method is as follows:

[0069]

[0070] In t...

Embodiment 2

[0079] The corn in embodiment 1 is replaced by soybean, as figure 1 As shown, there are 707 soybean sampling points;

[0080] In step 4, determine the correlation model of N and NDVI as: N=7.09*NDVI 2 -8.54*NDVI+4.34, where R 2 =0.59.

Embodiment 3

[0082] The corn in embodiment 1 is replaced by rice, such as figure 1 As shown, there are 846 rice sampling points;

[0083] In step 4, determine the correlation model of N and NDVI to be: N=19.37*NDVI 2 -19.55*NDVI+5.6, where R 2 = 0.83.

[0084] The sampling points of the present invention are all over my country's Heilongjiang Province. Taking the three crops of corn, soybean and rice in Heilongjiang Province as an example, study σ 0 The relationship with θ, to establish a σ suitable for different growth stages of different crops 0 The universal incident angle normalization method improves the ability of radar data in ground object classification, target detection and surface parameter inversion.

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Abstract

The invention discloses a crop radar signal incident angle normalization method based on NDVI and belongs to the technical field of radar data processing. A problem that in the prior art, a cosine normalization method cannot meet the normalization requirements of radar incident angles of different crops in different growth stages is solved. The incidence angle normalization method comprises the following steps of firstly, determining latitude and longitude coordinates of a crop growth area to be analyzed; then, according to latitude and longitude coordinates of a growth area of the to-be-analyzed crop, extracting all radar data Sentinel-1 and all optical data Sentinel-2 of the to-be-analyzed crop in a growth cycle from a Sentinel data distribution website; obtaining an N value of each recording point of the to-be-analyzed crop in a growth cycle according to the data of each recording point; and constructing the correlation between N and NDVI, and substituting the correlation into a cosine normalization method calculation formula, thereby obtaining the back scattering data of the specific crop in which the radar incident angle effect is removed in the specific growth stage.

Description

technical field [0001] The invention belongs to the technical field of radar data processing, in particular to an NDVI-based method for normalizing the incident angle of crop radar signals. Background technique [0002] SAR data are commonly used for land cover classification, object detection, and inversion of surface parameters (leaf area index, snow water equivalent, and soil moisture). However, the radar backscatter coefficient (σ 0 ) varies with the incident angle (θ), exhibiting a significant incident angle effect. This incident angle effect can reduce the accuracy of change detection based crop classification and soil moisture estimation. In order to reduce the incident angle effect, it is necessary to normalize the incident angle. [0003] The cosine method is one of the widely used normalization methods. In the prior art, the cosine method uses a fixed N (N=0, 1, 2). However, studies have demonstrated that radar parameters (polarization), land cover type and cro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S17/90G01S7/48G06F17/18
CPCG01S17/90G01S7/4802G06F17/18
Inventor 冯壮壮郑兴明
Owner NORTHEAST INST OF GEOGRAPHY & AGRIECOLOGY C A S