QX/T 539-2020 in English
VALIDTechnical directive for the area change monitoring of sand land by using China High-Resolution Earth Observation System satellite
- Issued on:2020-01-21
- Implemented on:2020-05-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$233.00
本标准规定了高分辨率对地观测卫星沙地面积变化监测的数据准备、沙地判识方法、监测方法及流程。本标准适用于利用国产高分一号、高分二号或具有类似通道设计的高分卫星数据，开展沙地面积变化遥感监测和评价工作。
Introduction
Analysis of the technical framework of the standard
This standard constructs a complete technical chain from the acquisition of GF-1/GF-2 satellite data to the evaluation of sand changes, with the core including three modules:
| Technical module | Core content | Key technical indicators |
|---|---|---|
| Data preprocessing | Atmospheric correction + geometric correction + phase selection | Spatial resolution consistency requirements |
| Sand identification | NDVI+green reflectance+shape index | Threshold range see Appendix E |
| Change monitoring | Absolute change ΔS and relative change rate P | Principle of comparability of data from the same period |
Key technology implementation path
1. Multi-dimensional feature extraction
Using the spectral-texture-morphological triple criteria:
- NDVI calculation: strictly follow the (Rnir-Rred)/(Rnir+Rred) formula
- Shape index: quantify the complexity of sand boundaries through 4πS/L2
- Green light reflectance: the mean calculation needs to exclude cloud interference pixels
Application Case of Inner Mongolia Demonstration Area
Using GF-2 data, when T0=0.18 and T3=0.45 were set, the accuracy of sand recognition reached 89.7%
Recommendations for Implementation of Standards
1. Data Quality Control
It is recommended to add the following during the data processing stage:
- Cloud detection (≤10%)
- Radiation calibration error (≤5%)
- Geometric registration accuracy (≤1 pixel)
2. Parameter Localization Adjustment
Appendix E thresholds need to be corrected according to regional characteristics:
| Ecological zone type | NDVI adjustment suggestion | Shape index correction |
|---|---|---|
| Arid zone | Lower limit increased by 0.02 | Increased by 0.05 |
| Semi-humid zone | Upper limit reduced by 0.03 | Decreased by 0.1 |
Technical evolution analysis
Compared with GB/T34814-2017 grassland monitoring standard, the innovations of this standard are:
- Introducing Sobel operator edge detection (Appendix C)
- Using global optimization merging algorithm (Appendix D)
- Establishing a multi-parameter joint identification model
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