Rapid and Low-cost Measurement Method of Normalized Difference Vegetation Index in Different Scenes

Normalized difference vegetation index (NDVI) is an important index for quickly evaluating crop growth status. However, the current vegetation index detection equipment is expensive, the calculation process is complicated, and the influence of ambient light needs to be considered in real-time. Therefore, a method for reducing the cost of rapid detection of NDVI is of great significance. In this study, experiments were carried out in the laboratory, greenhouse, and field, and the formula for NDVI was derived according to the light characteristics. The vegetation index was calculated under the condition that only the crop reflection Digital Number (DN) value needed to be obtained. In the three light environments, we deduced and changed the calculation formula of NDVI, avoiding the use of whiteboards or complex internal calculations to remove the influence of the light environment. The red-light band 650 nm and the near-infrared band 780 nm were selected to construct NDVI. In the laboratory, the calculated value was the same as the real vegetation index. In the greenhouse, the correlation coefficient between the calculated NDVI and real values was 1±0.017. In the field, the correlation coefficient between the calculated NDVI and actual values was higher than 0.98±0.053. The results showed that the NDVI constructed according to the light characteristics had high consistency and small error with the real value.It can replace the high-cost NDVI detection method, which is of great significance in laboratory, greenhouse, and field applications.