Method and principle of normalized vegetation index monitoring

Normalized Vegetation Index (NDVI) is a commonly used vegetation index, which can be used to monitor the growth and health of vegetation. Its principle is based on the reflection characteristics of vegetation in red light and near infrared band, which is obtained by calculating the ratio of reflectance in red light and near infrared band.

Specifically, the calculation formula of NDVI is as follows:

NDVI = (near infrared spectrum-red)/(near infrared spectrum+red)

Among them, NIR represents the reflectivity of near infrared band, and red represents the reflectivity of red band. Through the mathematical calculation of the reflectivity of these two bands, a normalized value can be obtained, which can reflect the growth and health of vegetation.

The methods and principles of NDVI monitoring can be summarized as follows:

1. Select appropriate satellite remote sensing data or ground monitoring data, including reflectivity data in red and near infrared bands.

2. According to the NDVI formula, calculate the reflectivity data of red light and near infrared band, and get the NDVI value of each pixel.

3. The changing trend of 3.NDVI value can reflect the growth and health of vegetation. For example, the higher the NDVI value, the better the vegetation growth and the higher the health level; On the contrary, the lower the NDVI value, the worse the vegetation growth and the lower the health level.

4. Through the spatial analysis of NDVI data, the distribution and coverage of vegetation can be analyzed. For example, NDVI data can be used to determine the distribution area of vegetation and analyze the coverage and density of vegetation.

5. Combining meteorological data and soil data, we can further understand the influencing factors and laws of vegetation growth, and provide scientific basis for vegetation management and protection.

It should be pointed out that NDVI monitoring also has some limitations. For example, due to the influence of atmospheric absorption and scattering, the NDVI value may be disturbed by errors; In addition, NDVI monitoring can only reflect the overall growth and health of vegetation, and cannot provide more detailed information, such as chlorophyll content and soil moisture. Therefore, in practical application, it is necessary to comprehensively evaluate the health status and development trend of vegetation in combination with other monitoring methods and data.