A Ground Measurement Method of Leaf Area Index Based on Digital Image Processing Technology

Abstract

The invention discloses an indirect measurement of the leaf area index of a measuring point based on the principle of photography, the principle of light radiation, the principle of statistics and the technology of digital image processing. First, according to the imaging principle of the digital image sensor combined with the statistical principle, the interference factor generated by the dark current under no-light conditions is obtained, which is also called the radiation correction factor Δ; and then various typical ground environments are obtained by taking pictures of different typical grounds and performing correction processing. The relative reflection coefficient k i； , and finally by taking digital images of the ground under the canopy and the ground without the canopy at the measurement point (at the same time, that is, under the same weather conditions), after processing, the light at the measurement point passes through the canopy before and after (relative radiation intensity on the canopy, canopy The relative radiation intensity of the ground below), and then calculate the size of the leaf area index, the measurement accuracy is stable, and the processing speed is fast.

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...

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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

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