纹理步长对刺槐林叶面积指数估算的影响

摘要

以渭北地区刺槐林为研究对象,通过计算不同步长Quickbird影像的纹理参数,建立野外实测刺槐林叶面积指数(LAI)与纹理参数的线性回归方程,比较纹理步长对刺槐林LAI估算精度的影响,遴选出估算刺槐林LAI的最佳纹理步长.结果表明:对于角二阶矩阵(ASM)和熵(ENT),LAI估算精度随着步长的增加变化不大;对于对比度(CON)、非相似度(DIS)和同质性(HOM),LAI估算精度随着步长的增加而明显下降,步长为3时,r2达到最大值(分别为0.51、0.56和0.59);对于相关性(COR),在0°和135°角度下,LAI估算精度随着步长的增加而降低,在45°和90°角度下,步长对LAI估算精度无明显影响;对于变化量(VAR),步长对LAI精度影响不大.%The black locust plantations in Weibei area were chosen as the research objects.Texture features with different displacement of Quickbird image were calculated.A simple linear model was established between field measurement of LAI and texture parameter to compare the effect of texture displacement on the accuracy of LAI of black locust plantations and to select the optimum displacement of LAI estimation.The results indicated that the accuracy of LAI estimation was less affected by displacement for Angular Second Moment (ASM) and Entropy (ENT);for Contrast (CON),Dissimilarity (DIS) and Homogeneity (HOM),the accuracy of LAI estimation significantly decreased with the increase of displacement.When displacement was set as 3,the r2 value reached the maximum value (0.51,0.56 and 0.59 respectively);for Correlation (COR),the accuracy of LAI estimation decreased with the increase of displacement when the orientation was set as 0° and 135°.The displacement had no effects on the accuracy of LAI estimation when the orientation was 45° and 90°.Displacement had no effects on LAI estimation for Variance (VAR).