摘要
钙华是研究地壳运动、古气候等地质环境的重要载体,大规模的钙华景观不仅有利于研究地质演变,作为自然遗产具有很高的旅游价值和保护意义,由于全球气候变化与人为因素影响,钙华容易出现被破坏、退化等现象。为方便保护和修复钙华资源,本研究提出区别于传统实地勘察的高光谱识别方法,利用原始数据(OD)、多元散射(MSC)后数据、一阶导后(FD)数据、二阶导(SD)后数据经过主成分分析(PCA)、线性判别分析(LDA)方法降维后与支持向量机(SVM)、随机森林(RF)、BP神经网络、卷积神经网络(CNN)四种方法建立识别模型,并讨论了不同降维效果和数据类型对识别模型总体分类精度(OA)的影响,发现原始数据中PCA降维的效果比LDA降维效果好,其在PCA降维下的分类模型普遍精度要比LDA下的模型精度高;在本研究中,以MSC数据为输入的识别模型精度均值为88%,在四种数据的模型精度均值大小中位居第二,仅比第一位低0.1%,但其方差与标准差分别为0.043、0.042,远远小于其他三种数据的模型,说明MSC数据的识别模型要更加稳定;其次经过粒子群算法(PSO)优化的SVM分类模型在F1-score、kappa系数、OA三种性能指标的评价下性能显示优良,其中SD-PCA-PSO-SVM获得了98%的高精度。综上,在钙华识别过程中,未经优化的分类器选择MSC数据或PCA降维的原始数据作为输入,更容易获取高精度识别模型,选择合适的理论来优化模型也可提升模型的识别性能。
Travertine is a kind of travertine carbonate precipitate that is generated when huge quantities of carbon dioxide are released from the surface of the earth.The formation of a large-scale landscape from this type of precipitate often takes a considerable length of time.Therefore,the travertine landscape may be used as a significant carrier for the study of crustal movement,paleoclimate,and other geological settings.Furthermore,the large-scale travertine landscape,which is considered as a natural heritage,is significant for conservation with a high tourist value.This study focuses on the Huanglong Scenic Area in China,which is recognized as a global natural heritage site by the United Nations Educational,Scientific,and Cultural Organization(UNESCO).This area is renowned for its expansive surface travertine landscapes that include a wide variety of distinctive formations and vibrant colors.The travertine in Huanglong,on the other hand,has been experiencing major deterioration in recent years,such as blackening and algal erosion.Therefore,the recognition and monitoring of travertine is urgent.This study proposes a method of recognizing travertine based on hyperspectral reflectance data in order to facilitate the protection and restoration of travertine resources.This method can be used to effectively tackle the problems brought about by traditional field surveys that are time-consuming,labor-intensive and likely destructive to travertine landscapes.This study was conducted in the following procedure.Four types of data were taken as classification objects,that is,original data and other three types of data that were converted respectively by multiple scattering,first-order derivative and second-order inverse for the original data.Then,these four types of data were respectively reduced to their corresponding dimensions by Principal Component Analysis(PCA)and Linear Discriminant Analysis(LDA),according to the magnitude of the cumulative variance of the data.Finally,for the classification of these four types of data after dimension reduction,they were respectively put into four kinds of classifiers,namely,Support Vector Machines(SVM),Random Forests(RF),BP Neural Networks,and Convolutional Neural Networks(CNN).Overall Classification Accuracy(OA)was used as an evaluation index.In addition,Particle Swarm Algorithm(PSO)was used to optimize the penalty coefficient C and the Gammer parameter values of SVM.Afterward,the optimized SVM was applied to develop a recognition model of classification.Moreover,three indicators,namely,F1-Score,Kappa coefficient,and OA were utilized to assess the performance of SVM recognition model.In terms of the data type and the method of dimension reduction,the classification results of the recognition model established in this study were studied.In the aspect of the method of data dimension reduction,it was discovered that dimension reduction of the original data by PCA was superior to that by LDA.Furthermore,the classification model of the original data by PCA dimension reduction was generally more accurate than that by LDA.With regard to the type of data,the mean value of the model accuracy with MSC data as input was 88%,which was the second largest among the four types of data,only 0.1%lower than the first one.However,its variance and standard deviation were 0.043 and 0.042,respectively,much smaller than those of the models with the other three types of data,which indicated that the recognition model with MSC data was much more stable.Finally,the SVM classification model that was optimized by PSO demonstrated its outstanding performance when evaluated from the three performance indexes:F1-score,kappa coefficient,and OA.In general,this performance is superior to that of the unoptimized SVM recognition model,with the SD-PCA-PSO-SVM model the best performance among the three.Values of F1-Score,Kappa and OA of the classification results by optimized SVM were 0.93,0.92,and 0.98,respectively.In conclusion,it is easier for the unoptimized classifier to acquire a high-precision recognition model,if the MSC data or the original data processed by PCA dimension reduction were selected as the input in the recognition of travertine.Additionally,selecting an appropriate theory to optimize the model can also improve the recognition performance of the model.
作者
徐梦辉
王卫红
田硕娟
訾应昆
吴周航
王晓梦
向红瑶
范静
XU Menghui;WANG Weihong;TIAN Shuojuan;ZI Yingkun;WU Zhouhang;WANG Xiaomeng;XIANG Hongyao;FAN Jing(School of Environment and Resource,Southwest University of Science and Technology,Mianyang,Sichuan 621000,China;Mianyang S&T City Division,the National Remote Sensing Center of China,Mianyang,Sichuan 621000,China;Tianfu Institute of Research and Innovation,Southwest University of Science and Technology,Chengdu,Sichuan 610299,China;School of Civil Engineering and Architecture,Southwest University of Science and Technology,Mianyang,Sichuan 621000,China)
出处
《中国岩溶》
CAS
CSCD
北大核心
2024年第3期585-594,共10页
Carsologica Sinica
基金
国家自然科学基金-区域创新发展联合基金(U21A2016)。
关键词
钙华
高光谱
数据降维与变换
粒子群算法
支持向量机
travertine
hyperspectral image
data dimension reduction and transformation
particle swarm optimization
support vector machine
