Detection of LAI for fruiter based on hemispherical photography

To solve the error from data acquisition to data processing in the traditional method and improve the standards in the method of operation, a hemisphere photography detecting system for shooting single fruiters from different positions by using fisheye lens was designed. The images were processed to obtain the LAI measuring value which would be validated with the true value, in order to study the influencing factors of the measurement of LAI. The results showed that fisheye lens shooting in different directions, offsets, and heights and using different software processing methods influenced the measurement of LAI. The optimal parameters were as follows: filming direction from the fruit tree of the east, distance between the fisheye lens and the citrus tree trunk of 25 cm , height from the ground of 89 cm. LAI4R was used, the Zenith Angle was 60, the areas irrelevant to the canopy was covered by using software mask function. With the above conditions, the coefficient of determination R2 of the linear regression model was 0.8268. The average absolute error and the average relative error between the measured value and the true value was 0.31% and 14.19%, respectively. This study provides a reference for the detection of the LAI of single fruiters.