REMOTE SENSING IMAGE SELECTION STRATEGY FOR RAPE RECOGNITION IN MOUNTAINOUS AREAS OF SOUTH CHINA——TAKING LUOPING COUNTY,YUNNAN PROVINCE AS AN EXAMPLE
The precise identification of rapeseed is crucial for the yield estimation and edible oil supply in China.In the southern mountainous areas with cloudy and rainy climates and fragmented fields,the choice of remote sensing image data sources directly affects the accuracy of rapeseed planting information extraction.To carry out professional precise measurement of rapeseed,it is necessary to clarify the applicability of various types of remote sensing data in rapeseed identification,explore the contribution of various remote sensing features to the accuracy of rapeseed identification process,and summarize the image selection strategy for extracting rapeseed in different scenarios in southern mountainous areas.This study used GF-2 PMS,GF-6 PMS,Sentinel-2 optical image data,and Sentinel-1 radar data,combined with support vector machine classification algorithm to identify and extract rapeseed in the mountainous area of Luoping county,Yunnan province,and analyze its accuracy.In the key time window(rapeseed flowering period)and non-key time window of rapeseed,design schemes were proposed to explore the contribution of rapeseed identification accuracy from spatial resolution features,time features,and time-series radar features,and analyze the reasons affecting the accuracy.The results were showed as follows.(1)The fragmented area of rapeseed was more sensitive to the reduction of spatial resolution,and could rapeseed be effectively recognized only when the resolution was better than 16 m.(2)From the standpoint of temporal features,single-time key time window optical images(Producer's Accuracy 99.69%,User's Accuracy 96.24)>time-series optical images(Producer's Accuracy:98.59,User's Accuracy:93.61)>single-time non-key time window optical images(Producer's Accuracy:91.90,User's Accuracy:87.99).(3)With respect to radar features,time-series VV+VH polarization feature radar images were superior to any single polarization,single-time radar feature images.These could substitute for optical images in overcast or rainy conditions to achieve optimal classification results(Producer's Accuracy:95.60,User's Accuracy:92.04).In summary,the findings from this study can offer suitable strategies for complex image data acquisition scenarios and serve as a reference for selecting image solutions for professional rapeseed measurement and application in southern mountainous areas.
identification accuracy of rapespatial resolutiontime characteristicsradar characteristicsimage selection strategy
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