Calculation Of Light Distribution To Apple Tree Canopy

Study on light distribution of apple tree canopy is one of the important way to optimize type of fruit trees and to improve potential production. use of light energy reasonably, effectively and optimize light distribution within the fruit tree canopy has the vital significance for the formation of fruit tree growth and fruit quality. In this paper, calculation method of light distribution to free spindle apple canopy were carried on the thorough research with the support of national natural science fund project (No:31371532), The main research contents were as follows:(1) Study on registration of multi-source image for3D reconstruction of apple tree canopyIn order to construct colorful three-dimensional spatial structure of canopy accurately, apple tree canopied of canopy in stable period were set for research object, the PMD camera and color camera were used to acquisite multi-source organ images of apple tree canopies, which aimed at studying registration of multi-source images. SIFT algorithm was used to extract characteristic points from multi-source images and RANSAC algorithm which optimized by objective function was adopted to purify feature vectors, which overcame scale change and effect of light. Bilinear mapping algorithm was employed as spatial mapping between multi-source images, which avoided inaccuracy of using affine transformation to solve space mapping. Test result showed that the accuracy can be reached to72.7%, provided accurate mapping relationship for3-D shape with color information.(2) Study on the three dimentional reconstruction of apple tree canopyBased on the research content above, the canopy images mosaics have been realized through Laplace pyramid decomposition and reconstruction algorithm as well as different fusion rules for different frequency bands of pyramid decomposition, which overcame the disadvantages of obvious mosaic trace and bad capacity of reflecting details for fusion images, and then principal component analysis and iterative closest point algorithms were used to complete the3D reconstruction of the apple tree canopy with color information. Test result showed that the error is3.25cm, make up missing data caused by a single angles, improved the accuracy of3D reconstruction for morphology of apple tree canopy effectively.(3) Study on the light distribution of apple tree canopy based on color information of3D cloudAs a theoretical basis that image color information changed correspondingly as the light intensity and based on the3D model of apple tree canopy, quantum genetic algorithm was used to optimize the initial values of parameters of fuzzy neural network, and then quantum genetic fuzzy neural network was constructed to be as the prediction model for the light distribution,which based on3D model of apple tree canopy in natural enviroment. Test result showed that accuracy of light distribution calculation is83.1%, improved the calculation precision of light distribution to apple tree canopy in natural environment(4) Study on the light distribution of apple tree canopy based on spectral characteristicsSpectral reflectance was analyzed, and first order differential spectrum was solved, which used to determine red edge position and the maximum of first order differential spectrum in different light area. The maximum of first order differential spectrum in red light area (680nm-760nm) was used as valid value to distinguish different light areas, which was made relative analysis with different light areas, and based on the research above, the prediction model was constructed to predict light intensity. Test result showed that accuracy of light distribution calculation was89.4%, of provided another kind of new way to compute light distribution for apple tree canopy accurately and efficiently.(5) Study on the photosynthetic characters of different light distribution areas based on spectral characteristicsBased on the spectral characteristics of different light areas, the chlorophyll fluorescence properties containing photochemical efficiency, potential maximal photochemical quantum efficiency, apparent photosynthetic quantum transmission efficiency, and photosynthetic characters containing net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration were obtained synchronously, which was used to make correlation analysis with maximum of first order differential, and then evaluate the validity of the model, for the purpose of rapid, accurate grasp the canopy photosynthetic capacity of different light area. The test results show that:calculation accuracy of the photosynthetic traits was above80%, provided an effective computational method of photosynthetic capacity for apple tree canopy.