Monitoring rice growth stages based on time series HJ-1A/1B CCD images

Crop growth stages information in large-scale is crucial to guide the management and decision-making in agriculture production. In order to obtain a precise information, a wavelet-based method for estimating rice growth stages was proposed based on 42 cloudless HJ-1A/1B CCD images in Hunan’s double cropping rice growth period in 2009 and 2010. Firstly, a time-series EVI dataset at day frequency at pixel scale was built by linear interpolation. Then a profile, which reflects the rice growth process, was produced by filtering based on wavelet analysis. At last, the critical growth stages could be estimated according to the characteristics of the curve. As an example, 20 parcels in situ investigation for rice heading date in Yuanjiang City were used to verify the results, and the wavelet-based method was compared to those based on non-symmetrical Gaussian function and Savitzky-Golay filtering. The result showed that the proposed method , with an average error of 3 days which was less than the latter's errors, could accurately monitor heading date of double cropping rice . This method is available in monitoring rice crop growth stages.