Leaf area index ground measurement method based on digital image processing technology

Abstract

The invention discloses a method for carrying out indirect measurement on leaf area index at a measurement point based on the principle of photography, the principle of optical radiation, the principle of statistics and the digital image processing technology. The method comprises the following steps: to begin with, obtaining dark current interference factor, also known as radiation correction factor delta, under a dark condition through combination of the digital image sensor imaging principle and the principle of statistics; carrying out shooting and correction processing on different typical grounds to obtain relative reflection coefficients ki of various typical ground environments; and finally, shooting digital images of a ground under a canopy and a canopy-free ground at the measurement point (shooting is carried out simultaneously, that is, in the same weather condition), after processing, obtaining relative radiation intensity of light rays at the measurement point before and after passing through the canopy(relative radiation intensity above the canopy and relative radiation intensity of the ground under the canopy), and calculating leaf area index. The method is high in measurement accuracy and stability, and fast in processing speed.

Description

technical field [0001] The invention belongs to the technical field of Leaf Area Index (LAI for short), and more specifically relates to a ground measurement method for the Leaf Area Index based on digital image processing technology. Background technique [0002] Vegetation is an important component of terrestrial ecosystems, and leaves are an important organ for the interaction between vegetation and the outside world. LAI is an important parameter to quantitatively describe the photosynthesis, respiration, and transpiration of vegetation. Widely used in climate, ecology, agriculture and other fields, it is defined as half of the leaf area of ​​the vegetation canopy per unit surface area. [0003] The ground measurement methods of LAI can be divided into direct and indirect measurement. The direct measurement method is to directly measure the surface area of ​​the blade, and the reliability of the measurement results can be guaranteed, but the time cost and cost cost of t...

AI Technical Summary

Problems solved by technology

However, some researchers pointed out that from the actual measurement results, when the leaf area index is greater than 1.5, the measurement accuracy of this method is significantly reduced, and it is more susceptible to the impact of image classification accuracy.

At the same time, the measurement accuracy of the image measurement device is greatly affected by the thickness of the canopy and the type of canopy, and the measurement accuracy is not high

[0007] Among various measurement methods, radiometry has more theoretical basis in comparison. The difficulty lies in how to accurately obtain the transmittance of light before and after passing through the canopy without being affected by other factors such as light intensity, sunny and cloudy weather, etc. In other words, due to the influence of other factors, it is impossible to accurately obtain the transmittance of light before and after passing through the canopy, so the measurement accuracy needs to be improved

Images