无人机影像拼接软件在农业中应用的比较研究

无人机遥感为精准农业管理提供了新的工具。实现无人机影像高精度自动拼接是开展无人机遥感应用的基础。目前,已有不同无人机影像拼接软件在几何精度斱面性能比较的研究,但关于光谱精度斱面还未有相关研究,而其对定量遥感反演非常重要。本研究比较了目前最受欢迎的两款无人机拼接软件Pix4D和Photoscan在农业应用时,拼接影像过程对原始影像光谱信息的影响,以为用户推荐最优软件。为此,基于冬小麦氮肥梯度试验,本研究在小麦生长季利用无人机搭载多光谱传感器获取相关影像,幵将其分别基于Pix4D软件, Photoscan软件拼接处理。同时,基于传感器厂商提供的单张影像处理技术,将每次传感器拍摄数据处理成未拼接的单张多光谱影像。基于以上数据,在施肥处理小区随机布设样点,分别提取3种类型影像上的样点光谱信息,比较它们光谱反射率及其对比度的差异。结果表明,尽管Pix4D拼接影像和Photoscan拼接影像各波段光谱反射率都与单张影像的反射率有显著相关性,但与Pix4D拼接影像相比, Photoscan拼接影像的光谱反射率和变异系数与原始单张影像之间更为接近。Photoscan能保留更多的原始光谱信息。结合已有关...

A comparison of photogrammetric software packages for mosaicking unmanned aerial vehicle (UAV) images in agricultural application

Unmanned aerial vehicle (UAV) remote sensing technology provides a new tool for precise agricultural management. High precision automatic stitching of UAV images is the basis for application of UAV remote sensing technology. At present, there exist researches to compare the performance of stitching software packages on their spatial precision, but few researches on the evaluation of their spectral precision, which is very important for quantitative remote sensing inversion. The objective of this study was to compare the influence of the two most popular UAVs orthomosaic-processing software packages, Pix4D and Photoscan, on the spectral information of original single image when stitching the image in agricultural application and to recommend the better one for users. For this purpose, multispectral sensor was carried on a UAV to acquire images over a winter wheat fertilization experiment. The acquired images were processed by Pix4D and Photoscan software packages to produce mosaicked image. In the meanwhile, single multispectral images were also produced using the method released by sensor manufacturer. Based on above data, randomly placed samples in the fertilization treatment, extracted spectral information of each point in the three types of images individually, and compared their reflectance value and image contrast. Although there were significant correlations in reflectance values between the mosaicked images proceed by Pix4D and Photoscan and the single image for each band, the reflectance value and its coefficients of variation from Photoscan mosaicked image were closer to the corresponding values of single image, compared with Pix4D mosaicked image. It means Photoscan retains more spectral information of the original image during stitching image. Considering the geometric accuracy results and software package prices from existing studies, Photoscan is suggested as the better package for users.