Development of a Simplified Radiometric Calibration Framework for Water-Based and Rapid Deployment Unmanned Aerial System (UAS) Operations

The current study sets out to develop an empirical line method (ELM) radiometric calibration framework for the reduction of atmospheric contributions in unmanned aerial systems (UAS) imagery and for the production of scaled remote sensing reflectance imagery. Using a MicaSense RedEdge camera flown on a custom-built octocopter, the research reported herein finds that atmospheric contributions have an important impact on UAS imagery. Data collected over the Lower Pearl River Estuary in Mississippi during five week-long missions covering a wide range of environmental conditions were used to develop and test an ELM radiometric calibration framework designed for the reduction of atmospheric contributions from UAS imagery in studies with limited site accessibility or data acquisition time constraints. The ELM radiometric calibration framework was developed specifically for water-based operations and the efficacy of using generalized study area calibration equations averaged across variable illumination and atmospheric conditions was assessed. The framework was effective in reducing atmospheric and other external contributions in UAS imagery. Unique to the proposed radiometric calibration framework is the radiance-to-reflectance conversion conducted externally from the calibration equations which allows for the normalization of illumination independent from the time of UAS image acquisition and from the time of calibration equation development. While image-by-image calibrations are still preferred for high accuracy applications, this paper provides an ELM radiometric calibration framework that can be used as a time-effective calibration technique to reduce errors in UAS imagery in situations with limited site accessibility or data acquisition constraints.

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Development of a Simplified Radiometric Calibration Framework for Water-Based and Rapid Deployment Unmanned Aerial System (UAS) Operations

10.20944/preprints202003.0469.v1 ◽

2020 ◽

Author(s):

Christopher M. Zarzar ◽

Padmanava Dash ◽

Jamie L. Dyer ◽

Robert Moorhead ◽

Lee Hathcock

Keyword(s):

River Estuary ◽

Pearl River Estuary ◽

Pearl River ◽

Acquisition Time ◽

Radiometric Calibration ◽

Calibration Technique ◽

Wide Range ◽

Data Acquisition Time ◽

Rapid Deployment ◽

Calibration Equations

The current study sets out to develop an empirical line method (ELM) radiometric calibration framework for reducing atmospheric contributions in UAS imagery and for producing scaled remote sensing reflectance imagery. Using a MicaSense RedEdge camera flown on a custom-built octocopter, the research reported herein finds that atmospheric contributions have an important impact on UAS imagery. Data collected over the Lower Pearl River Estuary in Mississippi during five week-long missions covering a wide range of environmental conditions was used to develop and test a simplified ELM radiometric calibration framework designed specifically for the reduction of atmospheric contributions to UAS imagery in studies with limited site accessibility or data acquisition time constraints. The framework was effective in reducing atmospheric and other external contributions to UAS imagery. Unique to the proposed radiometric calibration framework is the radiance to reflectance conversion conducted externally from the calibration equations which allows for the normalization of illumination independent from the time of UAS image acquisition and from the time of calibration equations development. This paper presents the simplified ELM radiometric calibration framework that can be used as a time-effective calibration technique to reduce errors in the UAS imagery.

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Projects MINEO and HyperGreen : airborne hyperspectral data acquisition in East Greenland for environmental monitoring and mineral exploration

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v189.5167 ◽

2001 ◽

pp. 122-126 ◽

Cited By ~ 2

Author(s):

Tapani Tukiainen

Keyword(s):

Environmental Monitoring ◽

Data Acquisition ◽

Mineral Exploration ◽

Hyperspectral Data ◽

Sensor Technology ◽

Radiometric Calibration ◽

Advanced Technique ◽

East Greenland ◽

Environmental Mapping ◽

Wide Range

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Tukiainen, T. (2001). Projects MINEO and HyperGreen: airborne hyperspectral data acquisition in East Greenland for environmental monitoring and mineral exploration. Geology of Greenland Survey Bulletin, 189, 122-126. https://doi.org/10.34194/ggub.v189.5167 _______________ In remote sensing terminology the word ‘hyperspectral’ is used to distinguish sensors with several tens or hundreds of bands from the traditional ‘multispectral’ sensors such as Landsat TM or Landsat MSS. The success of hyperspectral techniques relies on the detection of subtle variations in the spectral properties of one or more of the components being imaged. The advances of worldwide research and development in sensor technology to achieve higher signal to noise ratios, good operational stability and improved levels of spectral and radiometric calibration have provided the instrumental basis for the deployment of this advanced technique to a number of earth resource and environmental mapping and monitoring tasks. The analysis and interpretation of hyperspectral data are extensively based on the use of spectral libraries covering a wide range of inorganic and organic natural materials and comparison of data between different areas and sensor systems.

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Uncertainty Analysis for RadCalNet Instrumented Test Sites Using the Baotou Sites BTCN and BSCN as Examples

Remote Sensing ◽

10.3390/rs12111696 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1696 ◽

Cited By ~ 3

Author(s):

Lingling Ma ◽

Yongguang Zhao ◽

Emma R. Woolliams ◽

Caihong Dai ◽

Ning Wang ◽

...

Keyword(s):

Uncertainty Analysis ◽

International System ◽

Uncertainty Budget ◽

In Situ Monitoring ◽

Radiometric Calibration ◽

Atmospheric Conditions ◽

Vicarious Calibration ◽

Calibration And Validation ◽

System Of Units ◽

Wide Range

Vicarious calibration and validation techniques are important tools to ensure the long-term stability and inter-sensor consistency of satellite sensors making observations in the solar-reflective spectral domain. Automated test sites, which have continuous in situ monitoring of both ground reflectance and atmospheric conditions, can greatly increase the match-up possibilities for a wide range of space agency and commercial sensors. The Baotou calibration and validation test site in China provides operational high-accuracy and high-stability vicarious calibration and validation for high spatial resolution solar-reflective remote-sensing sensors. Two sites, given the abbreviations BTCN (an artificial site) and BSCN (a natural sandy site), have been selected as reference sites for the Committee on Earth Observation Satellites radiometric calibration network (RadCalNet). RadCalNet requires sites to provide data in a consistent format but does not specify the required operational conditions for a RadCalNet site. The two Baotou sites are the only sites to date that make spectral measurements for their continuous operation. One of the core principles of RadCalNet is that each site should have a metrologically rigorous uncertainty budget which also describes the site’s traceability to the international system of units, the SI. This paper shows a formalized metrological approach to determining and documenting the uncertainty budget and traceability of a RadCalNet site. This approach follows the Guide to the Expression of Uncertainty in Measurement. The paper describes the uncertainty analysis for bottom-of-atmosphere and top-of-atmosphere reflectance in the spectral region from 400 to 1000 nm for the Baotou sites and gives preliminary results for the uncertainty propagating this to top-of-atmosphere reflectance.

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An Evaluation of the Effects of UAS Flight Parameters on Digital Aerial Photogrammetry Processing and Dense-Cloud Production Quality in a Scots Pine Forest

Remote Sensing ◽

10.3390/rs13061121 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1121

Author(s):

Raul Sampaio de Lima ◽

Mait Lang ◽

Niall G. Burnside ◽

Miguel Villoslada Peciña ◽

Tauri Arumäe ◽

...

Keyword(s):

Data Acquisition ◽

Laser Scanning ◽

Model Fitting ◽

Ground Level ◽

Point Clouds ◽

Production Quality ◽

Unmanned Aerial Systems ◽

Aerial Photogrammetry ◽

Wide Range ◽

Scots Pine Forest

The application of unmanned aerial systems (UAS) in forest research includes a wide range of equipment, systems, and flight settings, creating a need for enhancing data acquisition efficiency and quality. Thus, we assessed the effects of flying altitude and lateral and longitudinal overlaps on digital aerial photogrammetry (DAP) processing and the ability of its products to provide point clouds for forestry inventory. For this, we used 18 combinations of flight settings for data acquisition, and a nationwide airborne laser scanning (ALS) dataset as reference data. Linear regression was applied for modeling DAP quality indicators and model fitting quality as the function of flight settings; equivalence tests compared DAP- and ALS-products. Most of DAP-Digital Terrain Models (DTM) showed a moderate to high agreement (R2 > 0.70) when fitted to ALS-based models; nine models had a regression slope within the 1% region of equivalence. The best DAP-Canopy Height Model (CHM) was generated using ALS-DTM with an R2 = 0.42 when compared with ALS-CHM, indicating reduced similarity. Altogether, our results suggest that the optimal combination of flight settings should include a 90% lateral overlap, a 70% longitudinal overlap, and a minimum altitude of 120 m above ground level, independent of the availability of an ALS-derived DTM for height normalization. We also provided insights into the effects of flight settings on DAP outputs for future applications in similar forest stands, emphasizing the benefits of overlaps for comprehensive scene reconstruction and altitude for canopy surface detection.

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Forest Inventory with Long Range and High-Speed Personal Laser Scanning (PLS) and Simultaneous Localization and Mapping (SLAM) Technology

Remote Sensing ◽

10.3390/rs12091509 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1509 ◽

Cited By ~ 3

Author(s):

Christoph Gollob ◽

Tim Ritter ◽

Arne Nothdurft

Keyword(s):

Data Acquisition ◽

Forest Inventory ◽

High Speed ◽

Laser Scanning ◽

Laser Scanner ◽

Acquisition Time ◽

Inventory Data ◽

Detection Rates ◽

Forest Inventory Data ◽

Wide Range

The use of new and modern sensors in forest inventory has become increasingly efficient. Nevertheless, the majority of forest inventory data are still collected manually, as part of field surveys. The reason for this is the sometimes time-consuming and incomplete data acquisition with static terrestrial laser scanning (TLS). The use of personal laser scanning (PLS) can reduce these disadvantages. In this study, we assess a new personal laser scanner and compare it with a TLS approach for the estimation of tree position and diameter in a wide range of forest types and structures. Traditionally collected forest inventory data are used as reference. A new density-based algorithm for position finding and diameter estimation is developed. In addition, several methods for diameter fitting are compared. For circular sample plots with a maximum radius of 20 m and lower diameter at breast height (dbh) threshold of 5 cm, tree mapping showed a detection of 96% for PLS and 78.5% for TLS. Using plot radii of 20 m, 15 m, and 10 m, as well as a lower dbh threshold of 10 cm, the respective detection rates for PLS were 98.76%, 98.95%, and 99.48%, while those for TLS were considerably lower (86.32%, 93.81%, and 98.35%, respectively), especially for larger sample plots. The root mean square error (RMSE) of the best dbh measurement was 2.32 cm (12.01%) for PLS and 2.55 cm (13.19%) for TLS. The highest precision of PLS and TLS, in terms of bias, were 0.21 cm (1.09%) and −0.74 cm (−3.83%), respectively. The data acquisition time for PLS took approximately 10.96 min per sample plot, 4.7 times faster than that for TLS. We conclude that the proposed PLS method is capable of efficient data capture and can detect the largest number of trees with a sufficient dbh accuracy.

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Cyanobacterial community diversity in the sediments of the Pearl River Estuary in China

Scientia Marina ◽

10.3989/scimar.04106.07a ◽

2017 ◽

Vol 81 (4) ◽

pp. 477

Author(s):

Fu-Lin Sun ◽

You-Shao Wang ◽

Mei-Lin Wu ◽

Cui-Ci Sun

Keyword(s):

Denaturing Gradient Gel Electrophoresis ◽

River Estuary ◽

Pearl River Estuary ◽

Community Diversity ◽

Pearl River ◽

Cyanobacterial Community ◽

The Pearl River Estuary ◽

Wide Range ◽

The Pearl River ◽

Outer Estuary

Cyanobacterial community diversity in the sediment of the Pearl River Estuary in China was evaluated in this study by denaturing gradient gel electrophoresis (DGGE) during the wet and dry seasons. Nucleotide sequences obtained from DGGE bands were classified into five cyanobacterial clusters, including Synechococcus, Cyanobium, Chroococcus, Prochlorales and Tolypothrix. Synechococcus was identified as the dominant cyanobacterial group in the sediment samples; its distribution varied from the inner estuary to the outer estuary, with a wide range of salinity adaptation. Observed patterns of cyanobacterial communities changed markedly between sampling sites and seasons, suggesting that most cyanobacteria were not delivered via fresh water. Canonical correspondence analysis was conducted to determine the relationship between environmental variables and bacterial community structures during the dry season. The results suggested that the cyanobacterial community was significantly influenced by pH, salinity, PO4-P and NO3-N in sediments.

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Analysis on Landscape Spatial Pattern Changes of Land Use and Its Driving Forces in Coastal Zone of Western Pearl River Estuary

Geo-information Science ◽

10.3724/sp.j.1047.2009.00436 ◽

2010 ◽

Vol 11 (4) ◽

pp. 436-441

Author(s):

Xiaoyu SUN ◽

Fenzhen SU ◽

Tingting LV ◽

Yi GAO

Keyword(s):

Land Use ◽

Spatial Pattern ◽

Coastal Zone ◽

Driving Forces ◽

River Estuary ◽

Pearl River Estuary ◽

Pearl River

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Acute toxicity ofCochlodinium geminatumbloom waters from Pearl River Estuary on larvae of brine shrimp,fish and shrimp

JOURNAL OF FISHERIES OF CHINA ◽

10.3724/sp.j.1231.2013.38620 ◽

2013 ◽

Vol 37 (9) ◽

pp. 1328

Author(s):

Ni WU ◽

Tao JIANG ◽

Tianjiu JIANG ◽

Songhui LV ◽

Qingliu HUAN

Keyword(s):

Acute Toxicity ◽

Brine Shrimp ◽

River Estuary ◽

Pearl River Estuary ◽

Pearl River

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A Real-Time Mathematical Model for Three-Dimensional Tidal Flow and Water Quality

Water Science & Technology ◽

10.2166/wst.1991.0154 ◽

1991 ◽

Vol 24 (6) ◽

pp. 171-177 ◽

Cited By ~ 1

Author(s):

Zeng Fantang ◽

Xu Zhencheng ◽

Chen Xiancheng

Keyword(s):

Mathematical Model ◽

Water Quality ◽

Real Time ◽

Control Volume ◽

Tidal Flow ◽

Three Dimensional ◽

River Estuary ◽

Pearl River Estuary ◽

Practical Application ◽

The Pearl River

A real-time mathematical model for three-dimensional tidal flow and water quality is presented in this paper. A control-volume-based difference method and a “power interpolation distribution” advocated by Patankar (1984) have been employed, and a concept of “separating the top-layer water” has been developed to solve the movable boundary problem. The model is unconditionally stable and convergent. Practical application of the model is illustrated by an example for the Pearl River Estuary.

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