基于MODIS-NDVI时序数据的南方冬闲田信息提取

为了从宏观上监测冬闲田的面积及分布情况有效解决传统方法的时效性差的缺陷，以MODIS-NDVI时间序列数据、土地利用数据和湖北省农业统计数据为基础，得到2007年4月到2008年3月湖北省MODIS-NDVI时序数据变化曲线。由于遥感影像在传输过程中受到云、大气等的影响，曲线的变化与统计数据的物候期并不完全符合。为了如实反映地表事物的真实面貌，本文采用Savitzky-Golay滤波进行平滑去噪处理，并将结果与ERDAS中自带的Hanning滤波去噪的结果进行比较，发现前者效果较好，不仅能有效去掉噪声，不产生环形条纹，而且能最大程度地保留细节特征。根据变化曲线所反映的物候信息，最后得到湖北省冬闲田的总面积为5564.3平方千米，即834.6万亩，占耕地总面积的16.6%，主要分布在鄂东南低山丘陵和江汉平原地区，冬闲期主要有60天和120天两种。

Information Extraction of Winter Fallow Fields in South China Based on MODIS-NDVI

In order to resolve the fault of traditional methods, MODIS-NDVI time series data, land-use plan in 1985 and Agricultural Statistics data of Hubei province were used to obtain MODIS-NDVI time series curve from April 2007 to March 2008 in Hubei Province. As a result of impacts by clouds, atmosphere during transmission, remote sensing images’curve fall short of statistical data, even sometimes appeared apparent dislocation phenomena with phenophase. In order to accurately reflect the true features of land surface, we used the Fourier transform to make time series data to frequency domain from space domain, used Savitzky-Golay filter for denoising processing and analysis, and then compared the results with that of Hanning denoising filter in ERDAS. Results showed that the former is better. It not only can remove noise, non-circular stripes, but also retain maximum details of the characteristics. Now, adopted the inverse Fourier transform to the results of Savitzky-Golay to get relatively smooth curve. Combined with phenological characteristics of Hubei Province, we made analysis on curve, and then according to the specific information curve, made classification to the original images from December 2007 to February 2008 in Hubei province. Two types of winter fallow fields and non-winter fallow fields were got considering the results of 9 image classification results, integrated the total results of winter fallow field’s distribution, area and number of days in Hubei province. The total areas of winter fallow fields is 5564.3 kilometers and most of them located in the southeast of Hubei province.