Comparative Results of Phenology Obtained from Satellite and Ground Observation Images on Paddy Field

Rice is the most significant economic crops in Thailand, which is required to monitor and estimate cultivated area in a wide region. Satellite images are often used to analyze for classifying the paddy area. To validate the results, it is necessary to have ground collection data. For the ground data, instead of field staffs, an equipment called Field Server (FS) has been installed and used to obtain daily images on the paddy field. In this paper, the comparative results of satellite and FS images are experimented in order to understand the correlation between two platforms. Based on the vegetation indices, satellite and FS images are computed for two phenological curves in an observation period. Two curves are compared by using a simple linear regression method (R squared), which can be described the correlation between each other. The phenological curve obtained from FS images is used as a reference. To determine the crop cycle on the satellite images (MODIS), we found that NDVI is more efficient than Excessive Green (ExG) index.