Extracting methods for forestry and grass coverage based on UAV visible light data and multispectral data
ZHAO Ying1, WANG Guanghui2, REN Jianfeng3, DU Wenzhen1, QIU Hao1
1. Water Resources Research Institute of Shandong Province, 250010, Jinan, China; 2. Weihai Water Conservancy Engineering Group Co. Ltd, 264200, Weihai, Shandong, China; 3. Binzhou Government Service Center, 256600, Binzhou, Shandong, China
Abstract:[Background] The remote sensing image obtained with unmanned aerial vehicle (UAV) has been widely used in soil and water conservation monitoring. However, compared with other industries, there are shortcomings in the UAV remote image, such as inadequate research depth, few application functions, and low monitoring accuracy. Moreover, images shot with different cameras and application of different classification methods will have impact on the monitoring accuracy of forest and grassland coverage in the monitoring process. The objective of our study is to provide a rapid and accurate method to monitor the coverage rate of forest and grass. [Methods] This study conducted a case study in Kenli, Dongying, Shandong province. The forest and grass coverage was calculated based on the multispectral data of UAV, and then the coverage was compared with the vegetation information extracted from the visible light. The visible light and multispectral images with high-resolutions were simultaneously obtained via UAV equipped with visible light and multispectral cameras having 5 multispectral sensors. Each camera was equipped with the same spectral resolution of 2 megapixels. Sixteen vegetation indices, including 8 multispectral vegetation indices and 8 visible light vegetation indices, were established, and the object-oriented threshold method and support vector machine method were used to extract the vegetation information and calculate the forest and grass coverage, respectively. Finally, the optimal vegetation index and classification method were chosen via the confusion matrix. [Results] The accuracy of vegetation index identified by multi-spectrum was over 90%, and the Kappa coefficient was over 0.90. Three types of visible light vegetation indices had reached the above level. The 11 vegetation indices mentioned above met the requirements of practical applications in soil and water conservation monitoring for the production and construction projects. In the classification method of multispectral vegetation indices, the available support vector machine methods were used in green ratio vegetation index (GRVI), soil-adjusted vegetation index (SAVI), green normalized difference vegetation index (GNDVI) and normalized differential index with red edge (NDRE), while the threshold methods were used in normalized difference vegetation index with red edge (RENDVI), enhanced vegetation index2 (EVI2), normalized difference vegetation index (NDVI) and optimized soil-adjusted vegetation index (OSAVI). The threshold methods were all used in the visible light vegetation indices, including red (R), green (G), and excess green vegetation index (EXG).Confirmatory experiments in three study areas showed that under normal conditions, better effects of vegetation information identification in calculating the forest and grass coverage might be obtained under both of the multispectral and visible light vegetation indices. In the presence of shadows, the single-band visible lights R and G were not well classified. On the contrary, the multispectral vegetation index presented better applicability and stability compared with the visible light covered index. [Conclusions] This study provides a high-precision extraction method to monitor the forestry and grass coverage for soil and water conservation based on UAV visible light data and multispectral data.
赵莹, 王光辉, 任建锋, 杜文贞, 邱浩. 基于无人机可见光及多光谱数据的林草覆盖率提取方法研究[J]. 中国水土保持科学, 2023, 21(5): 120-128.
ZHAO Ying, WANG Guanghui, REN Jianfeng, DU Wenzhen, QIU Hao. Extracting methods for forestry and grass coverage based on UAV visible light data and multispectral data. SSWC, 2023, 21(5): 120-128.
夏晨真,张月. 基于厘米级无人机影像的水土保持措施精准识别[J]. 水土保持学报,2020,34(5):111. XIA Chenzhen, ZHANG Yue. Accurate identification of soil and water conservation measures based on centimeter-resolution UAV images[J]. Journal of Soil and Water Conservation, 2020, 34(5):111.
[2]
李鹏飞. 基于无人机遥感的排土(矸)场立地对植被盖度影响研究[D]. 北京:北京林业大学,2021:13. LI Pengfei. Influence study of sites on vegetation coverage in dumps and gangue fields based on UAV remote sensing technology[D]. Beijing:Beijing Forestry University, 2021:13.
[3]
林成行,朱首军,周涛,等. 基于无人机遥感技术的水土保持植被恢复率提取[J]. 水土保持研究,2018, 25(6):211. LIN Chenghang, ZHU Shoujun, ZHOU Tao, et al. The extraction of vegetation recovery rate in soil and water conservation based on the technology of Unmanned Aerial Vehicle (UAV) remote sensing[J].Research of Soil and Water Conservation, 2018, 25(6):211.
[4]
崔万新,李锦荣,司前程,等. 基于无人机可见光波对荒漠植被覆盖率提取的研究[J]. 水土保持研究,2021,28(6):175. CUI Wanxin, LI Jinrong, SI Qiancheng, et al. Research on extraction method of desert shrub coverage based on UAV visible light data[J]. Research of Soil and Water Conservation, 2021, 28(6):175.
[5]
汪小钦,王苗苗,王绍强,等. 基于可见光波段无人机遥感的植被信息提取[J]. 农业工程学报,2015, 31(5):152. WANG Xiaoqin, WANG Miaomiao, WANG Shaoqiang, et al. Extraction of vegetation information from visible unmanned aerial vehicle images[J].Transactions of the CSAE, 2015, 31(5):152.
[6]
万炜,肖生春,陈小红,等. 无人机遥感在野外植被盖度调查中的应用:以阿拉善荒漠区灌木为例[J].干旱区资源与环境,2018,32(9):150. WAN Wei, XIAO Shengchun, CHEN Xiaohong, et al. Application of unmanned aerial vehicles to field vegetation coverage survey:A study of shrubs on Alxa desert[J]. Journal of Arid Land Resources and Environment, 2018, 32(9):150.
[7]
陈浩,冯浩,杨祯婷,等. 基于无人机多光谱遥感的夏玉米冠层叶绿素含量估计[J]. 排灌机械工程学报,2021,39(6):622. CHEN Hao, FENG Hao, YANG Zhenting, et al. Estimation of chlorophyll content of summer maize canopy based on UAV multispectral remote sensing[J]. Journal of Drainage and Irrigation Machinery Engineering,2021, 39(6):622.
[8]
李冰,刘镕源,刘素红,等. 基于低空无人机遥感的冬小麦覆盖度变化监测[J]. 农业工程学报,2012, 28(13):160. LI Bing, LIU Rongyuan, LIU Suhong, et al. Monitoring vegetation coverage variation of winter wheat by low-altitude UAV remote sensing system[J]. Transactions of the CSAE, 2012, 28(13):160.
[9]
徐存东,李洪飞,谷丰佑,等. 基于无人机遥感影像的盐碱地信息的精准提取方法[J]. 中国农村水利水电,2021(18):116. XU Cundong, LI Hongfei, GU Fengyou, et al. An accurate method to extract saline-alkali land information based on Unmanned Aerial Vehicle remote sensing image[J]. China Rural Water and Hydropower, 2021(18):116.
[10]
孙玉琳,黄宇,李伟,等.基于无人机多光谱影像的土地利用分类方法研究[J]. 新疆农机化,2022(2):11. SUN Yulin, HUANG Yu, LI Wei, et al.Research on land utilization and classification method based on UAV multispectral image[J]. Xinjiang Agricultural Mechanization, 2022(2):11.
[11]
牛庆林,冯海宽,周新国,等.冬小麦SPAD值无人机可见光和多光谱植被指数结合估算[J]. 农业机械学报,2021,52(8):183. NIU Qinglin, FENG Haikuan, ZHOU Xinguo, et al. Combining UAV visible light and multispectral vegetation indices for estimating SPAD value of winter wheat[J]. Transactions of the CSAM, 2021, 52(8):183.
[12]
高永刚,林悦欢,温小乐,等. 基于无人机影像的可见光波段植被信息识别[J]. 农业工程学报,2020,36(3):178. GAO Yonggang, LIN Yuehuan, WEN Xiaole, et al. Vegetation information recognition in visible band based on UAV images[J]. Transactions of the CSAE, 2020, 36(3):178.
[13]
左萍萍,付波霖,蓝斐芜,等. 基于无人机多光谱的沼泽植被识别方法[J]. 中国环境科学,2021,41(5):2399. ZUO Pingping, FU Bolin, LAN Feiwu, et al. Classification method of swamp vegetation using UAV multispectral data[J]. China Environmental Science, 2021, 41(5):2399.
[14]
张舒昱,李兆富,徐锋,等. 基于多时相无人机遥感影像优化河口湿地景观分类[J]. 生态学杂志, 2020,39(9):3174. ZHANG Shuyu, LI Zhaofu, XU Feng, et al. Optimization of estuary wetland landscape classification based on multi-temporal UAV images[J]. Chinese Journal of Ecology, 2020, 39(9):3174.
[15]
李美炫,朱西存,白雪源,等. 基于无人机影像阴影去除的苹果树冠层氮素含量遥感反演[J]. 中国农业科学,2021,54(10):2084. LI Meixuan, ZHU Xicun, BAI Xueyuan, et al.Remote sensing inversion of nitrogen content in apple canopy based on shadow removal in UAV multi-spectral remote sensing images[J]. Scientia Agricultura Sinica, 2021, 54(10):2084.
[16]
柳晓农,江洪,汪小钦. 构建植被区分阴影消除植被指数提取山地植被信息[J]. 农业工程学报,2019,35(20):135. LIU Xiaonong, JIANG Hong, WANG Xiaoqin. Extraction of mountain vegetation information based on vegetation distinguished and shadow eliminated vegetation index[J]. Transactions of the CSAE, 2019, 35(20):135.
[17]
许章华,刘健,余坤勇,等. 阴影植被指数SVI的构建及其在四种遥感影像中的应用效果[J]. 光谱学与光谱分析,2013,33(12):3359. XU Zhanghua, LIU Jian, YU Kunyong, et al. Construction of vegetation shadow index (SVI) and application effects in four remote sensing images[J]. Spectroscopy and Spectral Analysis, 2013, 33(12):3359.