低山丘陵区可见光谱的分形特征

Fractal Characteristics of Visible Spectra Across a Hilly Area

遥感影像记录的反射光谱特征主要来源于异质反射地物的光谱综合作用,了解其空间分布特征有助于影像解译和遥感模型的建立。该文以低山丘陵区10月底多光谱TM遥感影像为研究对象,采用统计学和多重分形相结合的手段分析其空间变异性。结果表明,研究区可见光谱(0.45～0.69μm)亮度值(digitalnumber,DN)空间分布表现出统计意义上的尺度不变性;广义分维函数Dq分析表明TM 2(0.52～0.60μm)DN值空间分布为单一分形,TM 1(0.45～0.52μm)和TM 3(0.63～0.69μm)DN值则表现出统计多重分形特征;多重分形谱参数(αmax-αmin)和[f(αmax)-f(αmin)]分析进一步显示TM 3DN值具有高度异质的空间分布特征和最丰富的信息量,其次是TM 1,而TM 2DN值则具有相对较低的空间异质性和信息量。

The spectral characteristic of remotely sensed image is mainly the results of integrative effects on spectrum from heterogeneous ground reflectors.Investigating its spatial distribution characteristics may be helpful for image interpreting and modeling based on remote sensing technique.In the present study,spatial heterogeneity of remotely sensed multispectral TM image across a hilly area in late October was studied by the combination of statistical method and multifractal analysis.The results showed that distribution of digital number（DN） values of visible spectra（0.45~0.69 μm） had statistical scale-invariance.The generalized fractal dimension function Dq suggested that distribution of TM 2（0.52~0.60 μm） DN values was monofractal type,whereas DN values of TM 1（0.45~0.52 μm） and TM 3（0.63~0.69 μm） had multifractal distribution characteristics.The parameters（αmax-αmin） and [f（αmax）-f（αmin）] of multifractal spectra further indicated that TM 3 DN values had the highest spatial heterogeneity and most abundant information,followed by TM 1,while the extremely narrow spectrum of TM 2 DN values showed its relatively low spatial heterogeneity and information capacity.