基于随机森林特征选择的城市绿化乔木树种分类

温小乐, 钟奥, 胡秀娟

The Classification of Urban Greening Tree Species Based on Feature Selection of Random Forest

WEN Xiaole,ZHONG Ao,HU Xiujuan

表2 从WorldView-2影像对象中提取的特征

Tab. 2 Image-object （IO） features extracted from WorldView-2 imagery

特征类型	特征名称	描述或公式
光谱特征	平均值	1-8波段的光谱平均值
	标准差	1-8波段的光谱标准差
指数特征	NDI₆₁	$\frac{ρ_{Red - Edge} - ρ_{Coastal}}{ρ_{Red - Edge} + ρ_{Coastal}}$
	NDI₈₄	$\frac{ρ_{NIR 2} - ρ_{Yellow}}{ρ_{NIR 2} + ρ_{Yellow}}$
	NDI₈₆	$\frac{ρ_{NIR 2} - ρ_{Red - Edge}}{ρ_{NIR 2} + ρ_{Red - Edge}}$
	NDI₆₅	$\frac{ρ_{Red - Edge} - ρ_{Red}}{ρ_{Red - Edge} + ρ_{Red}}$
	NDI₇₄	$\frac{ρ_{NIR 1} - ρ_{Yellow}}{ρ_{NIR 1} + ρ_{Yellow}}$
	NDI₈₅	$\frac{ρ_{NIR 2} - ρ_{Red}}{ρ_{NIR 2} + ρ_{Red}}$
	NDVI	$\frac{ρ_{NIR 1} - ρ_{Red}}{ρ_{NIR 1} + ρ_{Red}}$
	SAVI	$\frac{(ρ_{NIR 1} - ρ_{Red}) (1 + L)}{ρ_{NIR 1} + ρ_{Red} + L}, 其中 L = 0.5$
纹理特征	GLCM Mean	$\frac{\overset{N - 1}{\sum_{i, j = 0}} P_{i, j}}{N^{2}}$
	GLCM Std.dev	$\sqrt[]{\overset{N - 1}{\sum_{i, j = 0}} P_{i, j} (i, j - μ_{i, j})}$
	GLCM Homogeneity	$\overset{N - 1}{\sum_{i, j = 0}} \frac{P_{i, j}}{1 + {(i - j)}^{2}}$
	GLCM Contrast	$\overset{N - 1}{\sum_{i, j = 0}} P_{i, j} {(i - j)}^{2}$
	GLCM Dissimilarity	$\overset{N - 1}{\sum_{i, j = 0}} P_{i, j} \| i - j \|$
	GLCM Entropy	$\overset{N - 1}{\sum_{i, j = 0}} P_{i, j} (- \ln P_{i, j})$
	GLCM Angular second moment	$\overset{N - 1}{\sum_{i, j = 0}} (P_{i, j}) [\frac{(i, μ_{i}) (j - μ_{j})}{\sqrt[]{({σ_{i}}^{2}) ({σ_{j}}^{2})}}]$
	GLCM Correlation	$\overset{N - 1}{\sum_{i, j = 0}} (P_{i, j})^{2}$
	GLDV Entropy	$\overset{N - 1}{\sum_{k = 0}} V_{k} (- \ln V_{k})$
	GLDV Mean	$\overset{N - 1}{\sum_{k = 0}} k (V_{k})$
	GLDV Contrast	$\overset{N - 1}{\sum_{k = 0}} V_{k} k^{2}$
	GLDV Angular second moment	$\overset{N - 1}{\sum_{k = 0}} {V_{k}}^{2}$
几何特征	Compactness P	$\frac{4 \times π \times 面积}{周长}$
	Compactness	对象的紧致程度
	Shape index	对象的光滑程度
	Roundness	对象与椭圆的相似程度
	Border index	对象的不规则程度
	Number of edges	对象边的数量