基于多源高分卫星影像的果棉套种信息提取
Tree-cotton intercropping land extraction based on multi-source high resolution satellite imagery
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摘要: 棉花与果树间作在新疆多地区普遍存在,了解套种情况有利于查明果棉产量以及与常规棉田产量结构差异.为此,提出了一种综合使用多源高分遥感数据的果棉间作信息提取方法.首先,在优化分割尺度基础上分析QuickBird卫星数据的光谱、形状和纹理特征并建立规则集;其次,使用面向对象的分类方法逐步剔除非农田信息形成地块专题图,基于专题图选择最佳纹理特征提取果树分布并以地块为单位统计套种比例;最后,依据棉花物候特征对高分一号数据多时相分类得到棉花种植信息,结合套种比例结果,统计果棉套种面积及程度.精度检验结果表明: 该文提出的方法与传统抽样调查法相比能够为大量地块信息的采集节省人工成本和时间,果棉信息提取精度为89.16%,可以在统计调查工作中用于新疆果棉套种的自动化提取.Abstract: The intercropping system of tree-cotton is widespread in Xinjiang because it may increase yield and revenue especially during the early years of tree plantations.The statistics of the intercropped area is a key element for yield estimation.A method which can extract the tree-cotton intercropped ratio from planting area themetic map is proposed in this paper.The VHR (very high resolution) QuickBird imagery and multispectral high spatial resolution (GF-1) data were combined for extracting the intercropped ratio using the object-oriented approach and multi-seasonal classification approach respectively.Farmland extraction is a critical step to produce the intercropped information.Since multi-resolution segmentation (MRS) has been proved to be one of the most successful image segmentation algorithms, the trial-and-error process has been used to determine the three main optimal segmentation parameters (scale, shape, compactness) to identify farmland and tree canopy hierarchically.The new rule sets which consider optimal,shape and semantic features have been implemented to compile the farmland thematic map.Then, the GLCM-based texture feature has been proposed to distinguish the tree canopy when the image is segmented again.Intercropping ratio in each crop segmentation unit is calculated by stacking the farmland themetic layer and the tree canopy layer together.Since then, multi-seasonal classification approach has been used to extract the tree-cotton intercropping ratio from the intercropping ratio map.In addition, this work presents two varying images composed of GF-1 and Landsat8.By analyzing the phenologycal calendar, optimum temporal periods for cotton and other major crops are initially determined.Cotton planting areas are extracted by field samples supported supervised classification.The GF-1 accuracy achieves 89.16% which is by far better than TM results.Finally, tree-cotton interplanting area and ratio are extracted based on tree-crop intercropping map and cotton planting map.
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