Inversion Of Forest Canopy Leaf Area Index Based On FCM Color Image Segmentation

Leaf area index (LAI) is an important parameter to measure the photosynthetic capacity of plants on land. At present, direct methods and indirect methods are used for measuring LAI, hemispherical photography is one of the indirect methods. With the popularity of digital cameras and the continuous development of image processing technology, the image segmentation technology is applied to the determination of leaf area index. This paper studies the feasibility of measuring tree leaf area index (LAI) by color image segmentation, and obtains a more reliable method to estimate the leaf area index of the experimental plot of Maoershan.This study derive colorful forest canopy images through a camera with fisheye lens, then use improved FCM clustering technique to segment these images to obtain the porosity of forest canopy. Based on the model of canopy structure parameter, the leaf area index was obtained by canopy porosity which is get from image segmentation.Considering the obtained images are colorful images, in order to save more image information as far as possible this paper uses a method for color image segmentation. Firstly, make pretreatment through enhancing contrast and separating region; secondly, the traditional FCM clustering algorithm depends on the initial conditions, this paper made the corresponding improvement, use plug-in to determine the global optimum bandwidth, using mean shift algorithm in original image processing to obtain clustering number and clustering center of the image; clustering number and clustering center are introduced into the FCM algorithm, using the FCM algorithm for color image segmentation; and then, using improved OSTU to calculate image threshold value, the color image is converted into a binary image, work out the number of sky pixels, get the porosity of the canopy; ultimately, based on the Beer-Lamber law which is based on canopy group randomized distribution hypothesis and leaf angle distribution function of the light distribution model, leaf area index is inversed by the porosity through different methods such as single angle method, straight line fitting method, Miller formula method and iteration method. LAI is inversed by porosity which is obtained by experimental, find a suitable model for this experimental plot by comparison.