南京林业大学学报(自然科学版) ›› 2015, Vol. 58 ›› Issue (03): 6-12.doi: 10.3969/j.issn.1000-2006.2015.03.002

• 专题报道 • 上一篇    下一篇

基于SDA和CART算法的面向对象分类研究

张洋洋1,2,刘海娟1,2,张 婷1,2,徐雁南1,2*,侍 昊3   

  1. 1.南京林业大学林学院,江苏 南京 210037;
    2.南京林业大学南方现代林业协同创新中心,江苏 南京 210037;
    3.江苏省环境监测中心,江苏 南京 210036
  • 出版日期:2015-05-30 发布日期:2015-05-30
  • 基金资助:
    收稿日期:2014-03-14 修回日期:2015-01-07
    基金项目:江苏省环境监测科研基金项目(1416)
    第一作者:张洋洋,硕士生; 刘海娟,硕士生。*通信作者:徐雁南,教授。E-mail: nfuxyn@126.com。
    引文格式:张洋洋,刘海娟,张婷,等. 基于SDA和CART算法的面向对象分类研究[J]. 南京林业大学学报:自然科学版,2015,39(3):6-12.

Object-oriented classification based on SDA and CART algorithm

ZHANG Yangyang1,2, LIU Haijuan1,2, ZHANG Ting1,2, XU Yannan1,2*, SHI Hao3   

  1. 1.College of Forestry, Nanjing Forestry University,Nanjing 210037,China;
    2.Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China;
    3.Jiangsu Provincial Environmental Monitoring Center, Nanjing 210036, China
  • Online:2015-05-30 Published:2015-05-30

摘要: 以2005年深圳市福田区QuickBird影像为主要数据源,根据面向对象多尺度分割结果,构建和分析了不同地类对象的光谱、形状和纹理信息特征,在此基础上利用逐步判别分析法(stepwise discriminant analysis, SDA)结合分类回归树(classification and regression trees, CART)构建多尺度、多变量分类模型。结果表明:①采用SDA在一定程度上能够客观、准确地进行特征子集预筛选,笔者从32个特征中筛选出27个特征用于构建CART模型,并按其区分地类能力进行了重要性排序,其中光谱特征与纹理特征排序比较靠前,形状特征中仅LengthWidth排在第5位,剩余特征比较靠后。②利用分类回归树模型可进一步优化特征选取,并智能化计算出分离阈值,基本实现面向对象的自动化分类。其中Mean_b3、LengthWidth、Ratio_b3、GLDVE和NDVI是重要分类节点。③逐步判别分析结合分类回归树构建的分类模型,可以在提高或者不显著降低影像分类精度的条件下实现特征降维。当取相关指数R2>0.2时,构建的分类模型效果最优,CART16模型训练和验证精度分别为94.44%和83.37%,其特征子集规模最小,与原始特征数量相比减少了一半。

Abstract: Use the QuickBird remotely sensed imagery in 2005 of Futian District, Shenzhen City as the main data source, the spectrum, shape and texture features of different land-use were extracted by the object-oriented multiresolution segmentation. Then we used stepwise discriminant analysis(SDA)with classification and regression trees(CART)to build “multi-segmentation, multi-features” classification model. The results showed that:(1)With SDA, it could choose an advanced feature set. In this study, among the 32 features we totally chose 27 important features and sorted them by the importance in tables. Among them, the spectrum and texture features were mostly sorted forward, while the shape features were sorted later except the LengthWidth was ranked fifth.(2)The CART model could recognize more important features, and calculated separation thresholds for object-oriented classification automatically. In this study, Mean_b3, LengthWidth, Ratio_b3, GLDVE and NDVI features were the important classified nodes.(3)Under the condition of improving or no significantly reducing classification accuracy, SDA combined with CART model achieved the feature dimension reduction. When we chose R2>0.2, the CART16 model obtained an optimal result of training precision 94.44% and test precision 83.37%, while the feature set was the smallest, compared with primary one, the number of features decreased to half.

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