Canopy Image Analyzer

Introduction

The canopy image analyzer is used to study the canopy of plants at various heights. It uses fisheye lenses and CCD image sensors to obtain plant canopy images, and obtains relevant indicators and parameters of the plant canopy through dedicated analysis software. Using fisheye lens imaging to measure plant canopy data only requires one operation, which simplifies the complicated work of multiple measurements at fixed points in a day by traditional measurement methods. In addition, the canopy measurement using the image method can actively avoid the canopy gaps that do not meet the calculation of the canopy structure parameters, and can also avoid obstacles that do not meet the measurement calculation.

Test principle and method

The canopy image analyzer adopts the principle that canopy porosity is related to canopy structure. It is based on Beer's law that light is weakened when passing through a medium. Under the conditions of defining a series of assumptions for the plant canopy, a semi-theoretical and semi-empirical formula is used to calculate the canopy structure parameters through the determination of canopy porosity. This is the principle currently adopted by various canopy meters in the world. Based on the above principle, the plant canopy image analyzer uses the method of analyzing the hemispherical image of the sky dome under the canopy to measure the canopy porosity. This method is the most accurate and labor-saving, time-saving, quick and convenient method among all kinds of methods.

Structural composition

The canopy image analyzer consists of a fisheye image capture probe (consisting of a fisheye lens and a CCD image sensor), a measuring rod (rocker arm) with 25 built-in PAR sensors, a laptop computer, image acquisition software and image analysis software, and a high-capacity rechargeable battery pack. The fisheye probe is installed on the top of a very light rocker arm, which can obtain fisheye images with a viewing angle of 150°. The display and storage of the image are completed by the configured laptop computer.

Features

The fisheye lens can automatically maintain a horizontal state: the small fisheye camera lens designed specifically for plant canopy structure measurement is installed on a handheld universal balance joint, which can automatically keep the lens in a horizontal state without a tripod;

The fisheye lens can be extended into the canopy: the lens is installed at one end of the rocker arm. Due to its small size and the measuring rod, it can be easily extended horizontally forward or vertically upward to different heights of the canopy, and quickly perform layered measurements to measure the vertical distribution of light transmittance and leaf area index within the group;

Image analysis software: The image analysis software can arbitrarily define the image analysis area (the zenith angle can be divided into 10 areas, and the azimuth angle can be divided into 10 areas).

Unreasonable canopy parts can be shielded: When performing regional analysis of canopies in different directions, the ground objects and unreasonable canopy parts (such as missing plants, side row problems, etc.) can be arbitrarily shielded. The selection of different zenith angles of starting and ending angles can avoid canopy pore conditions that do not meet the calculation of the canopy structure parameters. By manually adjusting the threshold, parameters such as leaf area index can be measured more accurately;

Measurable indicators

Leaf area index

Average leaf inclination

Sky scattered light transmittance

Direct radiation transmittance of plant canopy at different solar altitudes

Extinction coefficient of canopy at different solar altitudes

Azimuth distribution of leaf area density

Main technical parameters

Lens angle: 150°

Resolution: 768×494pix

Measurement range: Zenith angle from 0° to 75° (150° fisheye lens) can be divided into ten areas, and azimuth angle 360° can also be divided into ten areas

PAR sensing range: Sensing spectrum 400nm to 700nm

Measuring range 0 to 2000μmol/㎡?S

Analysis software: Plant canopy analysis system

Power supply: 8.4v rechargeable lithium battery pack

Probe size: 6cm in diameter, 10cm in height

Total weight Weight: 500g (excluding laptop)

Transmission interface: USB

Operating temperature: 0～55℃

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