Research On Methods For Measuring Soil Water Content On-line Based On Digital Image Processing

At present, the grade of soil water content often adopt the mothod of feeling view to review in the farmland irrigation district. Due to depending on the person's feeling view to assess, the farmland manager's experience and hobby determine the grade judgment of soil water content, so the judgment exist certain subjective. Although there is also the other measuring method of soil water content, the low cost of realization, the method of on-line examination is less, which will restrict he progress that the area carries out electricity automation in the farmland irrigation district. With the computer increasingly universal, the computer"s function raise continuously, and the digital image processing's technique is also increasingly mature at the application of agriculture engineering, particularly is very extensive at the application of agriculture engineering. But to make use of computer vision to carry on the on-line examination of the soil water content, nobody carry on a deeply research up to now. This paper apply for computer vision and digital image processing's technique and put forward a kind of new method which measure soil surface water content on line. In the process of measuring soil surface water content, the CCD collects the picture quality of the soil surface water content will influence finally a measurement result directly. Therefore, this paper we extract the characteristic parameter of the image, that is gray-value, and carry through experiments for the relation between the gray-value of soil layer image and the soil water content after geometric correction, median filtering, image mode transform, and "bad area" filtrating to images of soil surface.The theoretical analysis and our experimental results show clearly that, there is an approximate linear function relation between the percentage of soil water content and average gray-value of soil layer image.