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Selected Papers from Agro-Geoinformatics 2018

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A special issue of Remote Sensing (ISSN 2072-4292). This special issue belongs to the section "Remote Sensing in Agriculture and Vegetation".

Deadline for manuscript submissions: closed (28 February 2019) | Viewed by 63632

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Special Issue Editors

Prof. Dr. Liping Di

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Guest Editor

Center for Spatial Information Science and Systems, George Mason University, 4400 University Drive, MSN 6E1, Fairfax, VA 22030, USA
Interests: earth system science; geospatial information science; agro-geoinformatics; geospatial web service; spatial data infrastructure; geospatial data catalog; interoperability standard; agricultural drought monitoring and forecasting
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Zhongxin Chen

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Guest Editor

Key Laboratory of Agricultural Remote Sensing, Ministry of Agriculture and Rural Affairs, China
Institute of Agricultural Resources and Regional Planning, CAAS, 12 Zhongguancun Nan Dajie, Beijing 100081, China
Interests: remote sensing applications in agriculture; data assimilation; agro-geoinformatics
Special Issues, Collections and Topics in MDPI journals

Assoc. Prof. Lizhen Lu

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Guest Editor

Institute of Geographic Information Science, Zhejiang University, Hangzhou, China
Interests: land use planning; geographic information system; agricultural remote sensing

Dr. Feng Gao

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Guest Editor

USDA-ARS Hydrology and Remote Sensing Laboratory, BARC-West, Beltsville, MD 20705-2350, USA
Interests: crop and vegetation condition monitoring; remote sensing data fusion
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Dr. Zhengwei Yang

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Guest Editor

Research and Development Division, National Agricultural Statistics Service, United States Department of Agriculture, Washington, DC 20250, USA
Interests: agricultural remote sensing; land use land cover; web services
Special Issues, Collections and Topics in MDPI journals

Dr. Liying Guo

E-Mail Website
Guest Editor

Center for Spatial Information Science and Systems, George Mason University, Fairfax, VA 22030, USA
Interests: agro-geoinformatic technology; sustainable development; land use and land cover change; public health; agricultural applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Agro-geoinformation is critical for research and decision making in agricultural sustainability, food security, environmental health, bioenergy, natural resource conservation, land use management, carbon accounting, global climate change, public health, agricultural commodity trading, rural economy, education, etc. Remote sensing is one of the main methods to collect agro-geoinformation and is the cornerstone in agro-geoinformatics research and applications. With the rapid advances in space-born, air-born, close-range and on-the-go remote sensing platforms, innovative sensors, information extraction algorithms, and data processing technologies, the agro-geoinformatic research and applications are booming in recent years, especially in the areas of handling digital agro-geoinformation, such as collecting (including in situ and remote sensing), processing, storing, archiving, preserving, retrieving, transmitting, accessing, visualizing, analyzing, synthesizing, presenting, modeling with, and disseminating agro-geoinformation.

This Special Issue will provide a venue for publishing papers describing innovative agro-geoinformatic research and applications. We welcome submissions that describe state of the art in all aspects of agro-geoinformatic research and application, including, but not limited to:

Research on agro-geoinformatic theory, methodology and practice
Quantitative agricultural remote sensing
Agricultural monitoring and management with geoinformatics
Precision agriculture
Agricultural land use and land cover change
Agricultural big data processing and cloud computing
Data assimilation with remotely sensed information
Spatial data uncertainty analysis
Agro-geoinformatic system
Agro-geoinformatic applications

Prof. Liping Di
Prof. Zhongxin Chen
Assoc. Prof. Lizhen Lu
Dr. Feng Gao
Dr. Zhengwei Yang
Assoc. Prof. Liying Guo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Remote Sensing is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Agro-geoinformatics
Quantitative remote sensing
Agriculture
Monitoring
Management
Data Processing
Big data
Data assimilation
Uncertainty analysis

Published Papers (12 papers)

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16 pages, 8810 KiB

Open AccessArticle

Estimation of Winter Wheat Residue Coverage Using Optical and SAR Remote Sensing Images

by Wenting Cai, Shuhe Zhao, Yamei Wang, Fanchen Peng, Joon Heo and Zheng Duan

Remote Sens. 2019, 11(10), 1163; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11101163 - 15 May 2019

Cited by 21 | Viewed by 4145

Abstract

As an important part of the farmland ecosystem, crop residues provide a barrier against water erosion, and improve soil quality. Timely and accurate estimation of crop residue coverage (CRC) on a regional scale is essential for understanding the condition of ecosystems and the interactions with the surrounding environment. Satellite remote sensing is an effective way of regional CRC estimation. Both optical remote sensing and microwave remote sensing are common means of CRC estimation. However, CRC estimation based on optical imagery has the shortcomings of signal saturation in high coverage areas and susceptibility to weather conditions, while CRC estimation using microwave imagery is easily influenced by soil moisture and crop types. Synergistic use of optical and microwave remote sensing information may have the potential to improve estimation accuracy. Therefore, the objectives of this study were to: (i) Analyze the correlation between field measured CRC and satellite derived variables based on Sentinel-1 and Sentinel-2, (ii) investigate the relationship of CRC with new indices (OCRI-RPs) which combine optical crop residues indices (OCRIs) and radar parameters (RPs), and (iii) to estimate CRC in Yucheng County based on OCRI-RPs by optimal subset regression. The correlations between field measured CRC and satellite derived variables were evaluated by coefficient of determination (R²) and root mean square error (RMSE). The results showed that the normalized difference tillage index (NDTI) and radar indices 2 (RI2) had relatively higher correlations with field measured CRC in OCRIs and RPs (R² = 0.570, RMSE = 6.560% and R² = 0.430, RMSE = 7.052%, respectively). Combining OCRIs with RPs by multiplying each OCRI with each RP could significantly improve the ability of indices to estimate CRC, as NDTI × RI2 had the highest R² value of 0.738 and lowest RMSE value of 5.140%. The optimal model for CRC estimation by optimal subset regression was constructed by NDI71 ×

σ_{V V}^{0}

and NDTI ×

σ_{V H}^{0}

, with a R² value of 0.770 and a RMSE value of 4.846%, which had a great improvement when compared with the best results in OCRIs and RPs. The results demonstrated that the combination of optical remote sensing information and microwave remote sensing information could improve the accuracy of CRC estimation. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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17 pages, 11125 KiB

Open AccessArticle

Clustering Tools for Integration of Satellite Remote Sensing Imagery and Proximal Soil Sensing Data

by Md Saifuzzaman, Viacheslav Adamchuk, Roberto Buelvas, Asim Biswas, Shiv Prasher, Nicole Rabe, Doug Aspinall and Wenjun Ji

Remote Sens. 2019, 11(9), 1036; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11091036 - 01 May 2019

Cited by 9 | Viewed by 4567

Abstract

Remote sensing (RS) and proximal soil sensing (PSS) technologies offer an advanced array of methods for obtaining soil property information and determining soil variability for precision agriculture. A large amount of data collected by these sensors may provide essential information for precision or site-specific management in a production field. Data clustering techniques are crucial for data mining, and high-density data analysis is important for field management. A new clustering technique was introduced and compared with existing clustering tools to determine the relatively homogeneous parts of agricultural fields. A DUALEM-21S sensor, along with high-accuracy topography data, was used to characterize soil variability in three agricultural fields situated in Ontario, Canada. Sentinel-2 data assisted in quantifying bare soil and vegetation indices (VIs). The custom Neighborhood Search Analyst (NSA) data clustering tool was implemented using Python scripts. In this algorithm, part of the variance of each data layer is accounted for by subdividing the field into smaller, relatively homogeneous, areas. The algorithm’s attributes were illustrated using field elevation, shallow and deep apparent electrical conductivity (EC_a), and several VIs. The unique feature of this proposed protocol was the successful development of user-friendly and open source options for defining the spatial continuity of each group and for use in the zone delineation process. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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15 pages, 4352 KiB

Open AccessArticle

Monitoring Extreme Agricultural Drought over the Horn of Africa (HOA) Using Remote Sensing Measurements

by Carolyn Qu, Xianjun Hao and John J. Qu

Remote Sens. 2019, 11(8), 902; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11080902 - 13 Apr 2019

Cited by 42 | Viewed by 7464

Abstract

The Horn of Africa ((HOA), including Djibouti, Eritrea, Ethiopia, and Somalia) has been slammed by extreme drought within the past years, and has become one of the most food-insecure regions in the world. Millions of people in the HOA are undernourished and are at risk of famine. Meanwhile, global climate change continues to cause more extreme weather and climate events, such as drought and heat waves, which have significant impacts on crop production and food security. This study aimed to investigate extreme drought in the Horn of Africa region, using satellite remote sensing data products from the Moderate Resolution Imaging Spectroradiometer (MODIS), a key instrument onboard the National Aeronautics and Space Administration (NASA) satellites Terra and Aqua, as well as Tropical Rainfall Measuring Mission (TRMM) precipitation data products. Normalized Difference Vegetation Index (NDVI), Vegetation Condition Index (VCI), Temperature Condition Index (TCI), and Vegetation Health Index (VHI) data from 2000 to 2017 were derived from the MODIS measurements and analyzed for assessments of the temporal trend of vegetation health and the impacts of extreme drought events. The results demonstrated the severity of vegetation stress and extreme drought during the past decades. From 1998 to 2017, monthly precipitation over major crop growth seasons decreased significantly. From 2001 to 2017, the mean VHI anomaly of HOA cropland decreased significantly, at a trend of −0.2364 ± 0.1446/year, and the mean TCI anomaly decreased at a trend of −0.2315 ± 0.2009/year. This indicated a deterioration of cropland due to drought conditions in the HOA. During most of the crop growth seasons in 2015 and 2016, the VHI values were below the 10-year (2001–2010) average: This was caused by extreme drought during the 2015–2016 El Niño event, one of the strongest El Niño events in recorded history. In addition, monthly VHI anomalies demonstrated a high correlation with monthly rainfall anomalies in July and August (the growth season of major crops in the HOA), and the trough points of the monthly rainfall and VHI anomaly time series of July and August were consistent with the timing of drought events and El Niño events. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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16 pages, 5183 KiB

Open AccessArticle

Assessment of the X- and C-Band Polarimetric SAR Data for Plastic-Mulched Farmland Classification

by Chang-An Liu, Zhongxin Chen, Di Wang and Dandan Li

Remote Sens. 2019, 11(6), 660; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11060660 - 18 Mar 2019

Cited by 11 | Viewed by 3168

Abstract

We present a classification of plastic-mulched farmland (PMF) and other land cover types using full polarimetric RADARSAT-2 data and dual polarimetric (HH, VV) TerraSAR-X data, acquired from a test site in Hebei, China, where the main land covers include PMF, bare soil, winter wheat, urban areas and water. The main objectives were to evaluate the outcome of using high-resolution TerraSAR-X data for classifying PMF and other land covers and to compare classification accuracies based on different synthetic aperture radar bands and polarization parameters. Initially, different polarimetric indices were calculated, while polarimetric decomposition methods were used to obtain the polarimetric decomposition components. Using these polarimetric components as input, the random forest supervised classification algorithm was applied in the classification experiments. Our results show that in this study full-polarimetric RADARSAT-2 data produced the most accurate overall classification (94.81%), indicating that full polarization is vital to distinguishing PMF from other land cover types. Dual polarimetric data had similar levels of classification error for PMF and bare soil, yielding mapping accuracies of 53.28% and 59.48% (TerraSAR-X), and 59.56% and 57.1% (RADARSAT-2), respectively. We found that Shannon entropy made the greatest contribution to accuracy in all three experiments, suggesting that it has great potential to improve agricultural land use classifications based on remote sensing. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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18 pages, 9544 KiB

Open AccessArticle

Near-Real-Time Flood Forecasting Based on Satellite Precipitation Products

by Nasreddine Belabid, Feng Zhao, Luca Brocca, Yanbo Huang and Yumin Tan

Remote Sens. 2019, 11(3), 252; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11030252 - 27 Jan 2019

Cited by 50 | Viewed by 7019

Abstract

Floods, storms and hurricanes are devastating for human life and agricultural cropland. Near-real-time (NRT) discharge estimation is crucial to avoid the damages from flood disasters. The key input for the discharge estimation is precipitation. Directly using the ground stations to measure precipitation is not efficient, especially during a severe rainstorm, because precipitation varies even in the same region. This uncertainty might result in much less robust flood discharge estimation and forecasting models. The use of satellite precipitation products (SPPs) provides a larger area of coverage of rainstorms and a higher frequency of precipitation data compared to using the ground stations. In this paper, based on SPPs, a new NRT flood forecasting approach is proposed to reduce the time of the emergency response to flood disasters to minimize disaster damage. The proposed method allows us to forecast floods using a discharge hydrograph and to use the results to map flood extent by introducing SPPs into the rainfall–runoff model. In this study, we first evaluated the capacity of SPPs to estimate flood discharge and their accuracy in flood extent mapping. Two high temporal resolution SPPs were compared, integrated multi-satellite retrievals for global precipitation measurement (IMERG) and tropical rainfall measurement mission multi-satellite precipitation analysis (TMPA). The two products are evaluated over the Ottawa watershed in Canada during the period from 10 April 2017 to 10 May 2017. With TMPA, the results showed that the difference between the observed and modeled discharges was significant with a Nash–Sutcliffe efficiency (NSE) of −0.9241 and an adapted NSE (ANSE) of −1.0048 under high flow conditions. The TMPA-based model did not reproduce the shape of the observed hydrographs. However, with IMERG, the difference between the observed and modeled discharges was improved with an NSE equal to 0.80387 and an ANSE of 0.82874. Also, the IMERG-based model could reproduce the shape of the observed hydrographs, mainly under high flow conditions. Since IMERG products provide better accuracy, they were used for flood extent mapping in this study. Flood mapping results showed that the error was mostly within one pixel compared with the observed flood benchmark data of the Ottawa River acquired by RadarSat-2 during the flood event. The newly developed flood forecasting approach based on SPPs offers a solution for flood disaster management for poorly or totally ungauged watersheds regarding precipitation measurement. These findings could be referred to by others for NRT flood forecasting research and applications. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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18 pages, 8978 KiB

Open AccessArticle

Improvement and Validation of NASA/MODIS NRT Global Flood Mapping

by Li Lin, Liping Di, Junmei Tang, Eugene Yu, Chen Zhang, Md. Shahinoor Rahman, Ranjay Shrestha and Lingjun Kang

Remote Sens. 2019, 11(2), 205; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11020205 - 21 Jan 2019

Cited by 51 | Viewed by 5525

Abstract

The remote-sensing based Flood Crop Loss Assessment Service System (RF-CLASS) is a web service based system developed and managed by the Center for Spatial Information Science and Systems (CSISS). The system uses Moderate Resolution Imaging Spectroradiometer (MODIS)-based flood data, which was implemented by the Dartmouth Flood Observatory (DFO), to provide an estimation of crop loss from floods. However, due to the spectral similarity between water and shadow, a noticeable amount of false classification of shadow can be found in the DFO flood products. Traditional methods can be utilized to remove cloud shadow and part of mountain shadow. This paper aims to develop an algorithm to filter out noise from permanent mountain shadow in the flood layer. The result indicates that mountain shadow was significantly removed by using the proposed approach. In addition, the gold standard test indicated a small number of actual water surfaces were misidentified by the proposed algorithm. Furthermore, experiments also suggest that increasing the spatial resolution of the slope helped reduce more noise in mountains. The proposed algorithm achieved acceptable overall accuracy (>80%) in all different filters and higher overall accuracies were observed when using lower slope filters. This research is one of the very first discussions on identifying false flood classification from terrain shadow by using the highly efficient method. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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20 pages, 8884 KiB

Open AccessArticle

Rapid Flood Progress Monitoring in Cropland with NASA SMAP

by Md. Shahinoor Rahman, Liping Di, Eugene Yu, Li Lin, Chen Zhang and Junmei Tang

Remote Sens. 2019, 11(2), 191; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11020191 - 19 Jan 2019

Cited by 40 | Viewed by 5972

Abstract

Research in different agricultural sectors, including in crop loss estimation during flood and yield estimation, substantially rely on inundation information. Spaceborne remote sensing has widely been used in the mapping and monitoring of floods. However, the inability of optical remote sensing to cloud penetration and the scarcity of fine temporal resolution SAR data hinder the application of flood mapping in many cases. Soil Moisture Active Passive (SMAP) level 4 products, which are model-driven soil moisture data derived from SMAP observations and are available at 3-h intervals, can offer an intermediate but effective solution. This study maps flood progress in croplands by incorporating SMAP surface soil moisture, soil physical properties, and national floodplain information. Soil moisture above the effective soil porosity is a direct indication of soil saturation. Soil moisture also increases considerably during a flood event. Therefore, this approach took into account three conditions to map the flooded pixels: a minimum of 0.05 m³m⁻³ increment in soil moisture from pre-flood to post-flood condition, soil moisture above the effective soil porosity, and the holding of saturation condition for the 72 consecutive hours. Results indicated that the SMAP-derived maps were able to successfully map most of the flooded areas in the reference maps in the majority of the cases, though with some degree of overestimation (due to the coarse spatial resolution of SMAP). Finally, the inundated croplands are extracted from saturated areas by Spatial Hazard Zone areas (SHFA) of Federal Emergency Management Agency (FEMA) and cropland data layer (CDL). The flood maps extracted from SMAP data are validated with FEMA-declared affected counties as well as with flood maps from other sources. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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18 pages, 4136 KiB

Open AccessArticle

Past and Future Trajectories of Farmland Loss Due to Rapid Urbanization Using Landsat Imagery and the Markov-CA Model: A Case Study of Delhi, India

by Junmei Tang and Liping Di

Remote Sens. 2019, 11(2), 180; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11020180 - 18 Jan 2019

Cited by 30 | Viewed by 4806

Abstract

This study integrated multi-temporal Landsat images, the Markov-Cellular Automation (CA) model, and socioeconomic factors to analyze the historical and future farmland loss in the Delhi metropolitan area, one of the most rapidly urbanized areas in the world. Accordingly, the major objectives of this study were: (1) to classify the land use and land cover (LULC) map using multi-temporal Landsat images from 1994 to 2014; (2) to develop and calibrate the Markov-CA model based on the Markov transition probabilities of LULC classes, the CA diffusion factor, and other ancillary factors; and (3) to analyze and compare the past loss of farmland and predict the future loss of farmland in relation to rapid urban expansion from the year 1995 to 2030. The predicted results indicated the high accuracy of the Markov-CA model, with an overall accuracy of 0.75 and Kappa value of 0.59. The predicted results showed that urban expansion is likely to continue to the year of 2030, though the rate of increase will slow down from the year 2020. The area of farmland has decreased and will continue to decrease at a relatively stable rate. The Markov-CA model provided a better understanding of the past, current, and future trends of LULC change, with farmland loss being a typical change in this region. The predicted result will help planners to develop suitable government policies to guide sustainable urban development in Delhi, India. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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18 pages, 7862 KiB

Open AccessArticle

Using the Bayesian Network to Map Large-Scale Cropping Intensity by Fusing Multi-Source Data

by Jianbin Tao, Wenbin Wu and Meng Xu

Remote Sens. 2019, 11(2), 168; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11020168 - 17 Jan 2019

Cited by 9 | Viewed by 3468

Abstract

Global food demand will increase over the next few decades, and sustainable agricultural intensification on current cropland may be a preferred option to meet this demand. Mapping cropping intensity with remote sensing data is of great importance for agricultural production, food security, and agricultural sustainability in the context of global climate change. However, there are some challenges in large-scale cropping intensity mapping. First, existing indicators are too coarse, and fine indicators for measuring cropping intensity are lacking. Second, the regional, intra-class variations detected in time-series remote sensing data across vast areas represent environment-related clusters for each cropping intensity level. However, few existing studies have taken into account the intra-class variations caused by varied crop patterns, crop phenology, and geographical differentiation. In this research, we first presented a new definition, a normalized cropping intensity index (CII), to quantify cropping intensity precisely. We then proposed a Bayesian network model fusing prior knowledge (BNPK) to address the issue of intra-class variations when mapping CII over large areas. This method can fuse regional differentiation factors as prior knowledge into the model to reduce the uncertainty. Experiments on five sample areas covering the main grain-producing areas of mainland China proved the effectiveness of the model. Our research proposes the framework of obtain a CII map with both a finer spatial resolution and a fine temporal resolution at a national scale. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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16 pages, 3084 KiB

Open AccessArticle

Estimation of Leaf Nitrogen Content in Wheat Using New Hyperspectral Indices and a Random Forest Regression Algorithm

by Liang Liang, Liping Di, Ting Huang, Jiahui Wang, Li Lin, Lijuan Wang and Minhua Yang

Remote Sens. 2018, 10(12), 1940; https://0-doi-org.brum.beds.ac.uk/10.3390/rs10121940 - 03 Dec 2018

Cited by 101 | Viewed by 6192

Abstract

Novel hyperspectral indices, which are the first derivative normalized difference nitrogen index (FD-NDNI) and the first derivative ratio nitrogen vegetation index (FD-SRNI), were developed to estimate the leaf nitrogen content (LNC) of wheat. The field stress experiments were conducted with different nitrogen and water application rates across the growing season of wheat and 190 measurements were collected on canopy spectra and LNC under various treatments. The inversion models were constructed based on the dataset to evaluate the ability of various spectral indices to estimate LNC. A comparative analysis showed that the model accuracies of FD-NDNI and FD-SRNI were higher than those of other commonly used hyperspectral indices including mNDVI₇₀₅, mSR, and NDVI₇₀₅, which was indicated by higher R² and lower root mean square error (RMSE) values. The least squares support vector regression (LS-SVR) and random forest regression (RFR) algorithms were then used to optimize the models constructed by FD-NDNI and FD-SRNI. The p-R² values of the FD-NDNI_RFR and FD-SRNI_RFR models reached 0.874 and 0.872, respectively, which were higher than those of the exponential and SVR model and indicated that the RFR model was accurate. Using the RFR inversion model, remote sensing mapping for the Operative Modular Imaging Spectrometer (OMIS) image was accomplished. The remote sensing mapping of the OMIS image yielded an accuracy of R² = 0.721 and RMSE = 0.540 for FD-NDNI and R² = 0.720 and RMSE = 0.495 for FD-SRNI, which indicates that the similarity between the inversion value and the measured value was high. The results show that the new hyperspectral indices, i.e., FD-NDNI and FD-SRNI, are the optimal hyperspectral indices for estimating LNC and that the RFR algorithm is the preferred modeling method. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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18 pages, 6363 KiB

Open AccessArticle

Object-Based Plastic-Mulched Landcover Extraction Using Integrated Sentinel-1 and Sentinel-2 Data

by Lizhen Lu, Yuan Tao and Liping Di

Remote Sens. 2018, 10(11), 1820; https://0-doi-org.brum.beds.ac.uk/10.3390/rs10111820 - 16 Nov 2018

Cited by 48 | Viewed by 5452

Abstract

Plastic mulching on farmland has been increasing worldwide for decades due to its superior advantages for improving crop yields. Monitoring Plastic-Mulched Land-cover (PML) can provide essential information for making agricultural management decisions and reducing PML’s eco-environmental impacts. However, mapping PML with remote sensing data is still challenging and problematic due to its complicated and mixed characteristics. In this study, a new Object-Based Image Analysis (OBIA) approach has been proposed to investigate the potential for combined use of Sentinel-1 (S1) SAR and Sentinel-2 (S2) Multi-spectral data to extract PML. Based on the ESP2 tool (Estimation of Scale Parameter 2) and ED2 index (Euclidean Distance 2), the optimal Multi-Resolution Segmentation (MRS) result is chosen as the basis of following object-based classification. Spectral and backscattering features, index features and texture features from S1 and S2 are adopted in classifying PML and other land-cover types. Three machine-learning classifiers known as the—Classification and Regression Tree (CART), the Random Forest (RF) and the Support Vector Machine (SVM) are carried out and compared in this study. The best classification result with an overall accuracy of 94.34% is achieved by using spectral, backscattering, index and textural information from integrated S1 and S2 data with the SVM classifier. Texture information is demonstrated to contribute positively to PML classifications with SVM and RF classifiers. PML mapping using SAR information alone has been greatly improved by the object-based approach to an overall accuracy of 87.72%. By adding SAR data into optical data, the accuracy of object-based PML classifications has also been improved by 1–3%. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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11 pages, 1754 KiB

Open AccessLetter

Bibliometric Analysis of Remote Sensing Research Trend in Crop Growth Monitoring: A Case Study in China

by Lijuan Wang, Guimin Zhang, Ziyi Wang, Jiangui Liu, Jiali Shang and Liang Liang

Remote Sens. 2019, 11(7), 809; https://0-doi-org.brum.beds.ac.uk/10.3390/rs11070809 - 04 Apr 2019

Cited by 36 | Viewed by 5029

Abstract

Remote sensing of crop growth monitoring is an important technique to guide agricultural production. To gain a comprehensive understanding of historical progression and current status, and future trend of remote sensing researches and applications in the field of crop growth monitoring in China, a study was carried out based on the publications from the past 20 years by Chinese scholars. Using the knowledge mapping software CiteSpace, a quantitative and qualitative analysis of research development, current hotspots, and future directions of crop growth monitoring using remote sensing technology in China was conducted. Furthermore, the relationship between high-frequency keywords and the emerging hot topics were visually analyzed. The results revealed that Chinese researchers paid more attention on keywords such as “vegetation index”, “crop growth”, “winter wheat”, “leaf area index (LAI)”, and “model” in the field of crop growth monitoring, and “LAI” and “unmanned aerial vehicle (UAV)”, appeared increasingly in frontier research of this discipline. Overall, bibliometric results from this CiteSpace-aided study provide a quantitative visualization to enrich our understanding on the historical development, current status, and future trend of crop growth monitoring in China. Full article

(This article belongs to the Special Issue Selected Papers from Agro-Geoinformatics 2018)

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