不同成像方式对棉花冠层特征光谱参数的影响

比较了拍摄角度、光照强度(阴天与晴天)与数码图像的获取模式等因素对图像质量及其应用的影响,以期建立标准的近地面数码图像获取方法。在获取棉花冠层图像时,在60°拍摄角度下获取的冠层特征光谱参数值与棉花全氮含量与叶片含氮量的相关性最好。在阴天与晴天下获取的冠层光谱参数之间没有显著性差异,但在阴天获取的图片更有利于处理图像工作的进行。在四种曝光模式下获取的特征光谱参数没有显著性差异,运用这几种模式都可用于数码影像信息采集。在3.0m下获得的冠层图像,其光谱参数的变异系数小于在1.0m下获取的变异系数,因此选择合适的拍摄高度十分必要。

Effect of Different Imaging Mode on Canopy Feature Spectral Parameter

With the practical experience of shooting cotton canopy digital image,the paper analyzes several critical factors on the digital image quality and application,according to shoot angle,light intensity and exposal model.It is expected to establish the standard method on shooting cotton canopy digital camera around the ground.For taking digital image of cotton canopy image in the field,the angle between digital camera and ground could be at 60 degree.Because at this degree,the decision coefficient is the best between the spectral parameter and total N concentration,the same is true to spectrum parameter and cotton leaves N concentration.The spectral parameters are not significantly different,when they were capturing in the cloudy day or sunny day.But it is beneficial for analysing digital image in cloudy days.No significant difference was observed among 4 exposal models,so each model can be adopted to take digital photos for crop growth information analysis.The coefficient of variation of the cotton canopy's spectral parameters at 3.0 meter is smaller than that at 1.0 meter,so it is important to choose the appropriate height for shooting images.