几种红边位置算法在潮滩区域的适用性研究——以长江口南汇潮滩为例

Applicability of Several Red Edge Position Algorithms in the Tidal Flat——Taking Nanhui Tidal Flat in the Yangtze River Estuary as an Example

植被反射率光谱的"红边位置"是判断植被健康状况的重要参数。本文以长江口南汇东滩优势种植被芦苇和海三棱藨草为研究对象,比较和分析了多项式拟合法、四点内插法、一阶导数法、拉格朗日内插法和线性外推法五种红边位置算法提取4个试验区域不同土壤湿度的芦苇和海三棱藨草植被红边位置的性能。研究结果表明多项式拟合法获取红边位置精度最高,对土壤湿度敏感性最大;四点内插法对土壤湿度敏感性较大;线性外推法得到的红边位置结果不稳定;一阶导数法和拉格朗日内插法相对于其他方法对土壤湿度敏感性最小,更适合在南汇潮滩这样高湿度土壤区域进行植被红边位置的信息提取。

The＂red edge position＂of the vegetation in its reflecting spectra is an important parameter to judge the vegetation health.Taking the dominant canopy species,the phragmites australis and scirpus mariqueter,in Nanhui tidal flat in the Yangtze River estuary as the research objects,five calculation methods of extracting the red edge position are compared and analyzed,including the polynomial fitting,the four-point interpolation,the first derivative technique,the Lagrange interpolation and the linear extrapolation.Four test areas with different soil moisture are selected for the analysis.The results show that the polynomial fitting has the highest accuracy for the red edge position and the maximum sensitivity to the soil moisture;the four-point interpolation method has moderate sensitivity to soil moisture;the linear extrapolation obtains unstable red edge position;the first derivative technique and Lagrange interpolation have the minimum sensitivity to soil moisture which are more suitable for obtaining the vegetation red edge position in such a high soil moisture area as the Nanhui tidal flat.