Estimating herbaceous aboveground biomass in Sahelian rangelands using structure from motion data collected on the ground and by UAV

1.Herbaceous aboveground biomass (HAB) is a key indicator of grassland vegetation and indirect estimation tools, such as remote sensing imagery, increase the potential for covering larger areas in a timely and cost-efficient way. Structure from motion (SfM) is an image analysis process that can create a 3D model from a set of images. 2: Computed from UAV and ground camera measurements, the SfM potential to estimate the herbaceous aboveground biomass in Sahelian rangelands was tested in this study. Both UAV and ground camera recordings were used at three different scales: temporal, landscape and national (across Senegal). All images were processed using PIX4D software and were used to extract vegetation indices and heights. 3: A random forest algorithm was used to estimate the HAB and the average estimation errors were around 150 g.m-² for fresh mass (20% relative error) and 60 g.m-² for dry mass (around 25% error). A comparison between different datasets revealed that the estimates based on camera data were slightly more accurate than those from UAV data. 4:It was also found that combining datasets across scales for the same type of tool (UAV or camera) could be a useful option for monitoring HAB in Sahelian rangelands or in other grassy ecosystem.

Download Full-text

PRELIMINARY STRUCTURE FROM MOTION DATA FOR THE TOWNE PASS FAULT, NORTHERN DEATH VALLEY NATIONAL PARK, CALIFORNIA

10.1130/abs/2017am-302776 ◽

2017 ◽

Author(s):

Amelia C. Nachbor ◽

◽

Paul Wetmore

Keyword(s):

Structure From Motion ◽

National Park ◽

Death Valley ◽

Motion Data ◽

Death Valley National Park

Download Full-text

Aboveground Biomass Mapping of Crops Supported by Improved CASA Model and Sentinel-2 Multispectral Imagery

Remote Sensing ◽

10.3390/rs13142755 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2755

Author(s):

Peng Fang ◽

Nana Yan ◽

Panpan Wei ◽

Yifan Zhao ◽

Xiwang Zhang

Keyword(s):

Aboveground Biomass ◽

Production Management ◽

Vegetation Index ◽

Net Primary Productivity ◽

Vegetation Indices ◽

Biophysical Parameters ◽

Edge Information ◽

Casa Model ◽

Red Edge ◽

Biomass Mapping

The net primary productivity (NPP) and aboveground biomass mapping of crops based on remote sensing technology are not only conducive to understanding the growth and development of crops but can also be used to monitor timely agricultural information, thereby providing effective decision making for agricultural production management. To solve the saturation problem of the NDVI in the aboveground biomass mapping of crops, the original CASA model was improved using narrow-band red-edge information, which is sensitive to vegetation chlorophyll variation, and the fraction of photosynthetically active radiation (FPAR), NPP, and aboveground biomass of winter wheat and maize were mapped in the main growing seasons. Moreover, in this study, we deeply analyzed the seasonal change trends of crops’ biophysical parameters in terms of the NDVI, FPAR, actual light use efficiency (LUE), and their influence on aboveground biomass. Finally, to analyze the uncertainty of the aboveground biomass mapping of crops, we further discussed the inversion differences of FPAR with different vegetation indices. The results demonstrated that the inversion accuracies of the FPAR of the red-edge normalized vegetation index (NDVIred-edge) and red-edge simple ratio vegetation index (SRred-edge) were higher than those of the original CASA model. Compared with the reference data, the accuracy of aboveground biomass estimated by the improved CASA model was 0.73 and 0.70, respectively, which was 0.21 and 0.13 higher than that of the original CASA model. In addition, the analysis of the FPAR inversions of different vegetation indices showed that the inversion accuracies of the red-edge vegetation indices NDVIred-edge and SRred-edge were higher than those of the other vegetation indices, which confirmed that the vegetation indices involving red-edge information can more effectively retrieve FPAR and aboveground biomass of crops.

Download Full-text

Rapid Quantification of Microalgae Growth with Hyperspectral Camera and Vegetation Indices

Plants ◽

10.3390/plants10020341 ◽

2021 ◽

Vol 10 (2) ◽

pp. 341

Author(s):

Pauliina Salmi ◽

Matti A. Eskelinen ◽

Matti T. Leppänen ◽

Ilkka Pölönen

Keyword(s):

Chlorophyll Fluorescence ◽

Chlorophyll A ◽

Near Infrared ◽

Vegetation Indices ◽

Hyperspectral Data ◽

Strong Correlations ◽

Algae Biomass ◽

Chlorophyll A Concentration ◽

Cost Efficient ◽

Hyperspectral Camera

Spectral cameras are traditionally used in remote sensing of microalgae, but increasingly also in laboratory-scale applications, to study and monitor algae biomass in cultures. Practical and cost-efficient protocols for collecting and analyzing hyperspectral data are currently needed. The purpose of this study was to test a commercial, easy-to-use hyperspectral camera to monitor the growth of different algae strains in liquid samples. Indices calculated from wavebands from transmission imaging were compared against algae abundance and wet biomass obtained from an electronic cell counter, chlorophyll a concentration, and chlorophyll fluorescence. A ratio of selected wavebands containing near-infrared and red turned out to be a powerful index because it was simple to calculate and interpret, yet it yielded strong correlations to abundances strain-specifically (0.85 < r < 0.96, p < 0.001). When all the indices formulated as A/B, A/(A + B) or (A − B)/(A + B), where A and B were wavebands of the spectral camera, were scrutinized, good correlations were found amongst them for biomass of each strain (0.66 < r < 0.98, p < 0.001). Comparison of near-infrared/red index to chlorophyll a concentration demonstrated that small-celled strains had higher chlorophyll absorbance compared to strains with larger cells. The comparison of spectral imaging to chlorophyll fluorescence was done for one strain of green algae and yielded strong correlations (near-infrared/red, r = 0.97, p < 0.001). Consequently, we described a simple imaging setup and information extraction based on vegetation indices that could be used to monitor algae cultures.

Download Full-text

Forest Aboveground Biomass Estimation and Mapping through High-Resolution Optical Satellite Imagery—A Literature Review

Forests ◽

10.3390/f12070914 ◽

2021 ◽

Vol 12 (7) ◽

pp. 914

Author(s):

Adeel Ahmad ◽

Hammad Gilani ◽

Sajid Rashid Ahmad

Keyword(s):

High Resolution ◽

Literature Review ◽

Satellite Imagery ◽

Aboveground Biomass ◽

Vegetation Indices ◽

Biomass Estimation ◽

Independent Variables ◽

Non Linear ◽

Multiple Variables ◽

Forest Aboveground Biomass

This paper provides a comprehensive literature review on forest aboveground biomass (AGB) estimation and mapping through high-resolution optical satellite imagery (≤5 m spatial resolution). Based on the literature review, 44 peer-reviewed journal articles were published in 15 years (2004–2019). Twenty-one studies were conducted across six continents in Asia, eight in North America and Africa, five in South America, and four in Europe. This review article gives a glance at the published methodologies for AGB prediction modeling and validation. The literature review suggested that, along with the integration of other sensors, QuickBird, WorldView-2, and IKONOS satellite images were most widely used for AGB estimations, with higher estimation accuracies. All studies were grouped into six satellite-derived independent variables, including tree crown, image textures, tree shadow fraction, canopy height, vegetation indices, and multiple variables. Using these satellite-derived independent variables, most of the studies used linear regression (41%), while 30% used linear (multiple regression and 18% used non-linear (machine learning) regression, while very few (11%) studies used non-linear (multiple and exponential) regression for estimating AGB. In the context of global forest AGB estimations and monitoring, the advantages, strengths, and limitations were discussed to achieve better accuracy and transparency towards the performance-based payment mechanism of the REDD+ program. Apart from technical limitations, we realized that very few studies talked about real-time monitoring of AGB or quantifying AGB change, a dimension that needs exploration.

Download Full-text

Developing bare-earth digital elevation models from structure-from-motion data on barrier islands

ISPRS Journal of Photogrammetry and Remote Sensing ◽

10.1016/j.isprsjprs.2021.08.014 ◽

2021 ◽

Vol 180 ◽

pp. 269-282 ◽

Cited By ~ 1

Author(s):

Nicholas M. Enwright ◽

Christine J. Kranenburg ◽

Brett A. Patton ◽

P. Soupy Dalyander ◽

Jenna A. Brown ◽

...

Keyword(s):

Structure From Motion ◽

Digital Elevation Models ◽

Barrier Islands ◽

Motion Data ◽

Digital Elevation

Download Full-text

REPRESENTATION AND DIGITALIZATION OF STONE THEATRES IN EASTERN SICILY: THE PALAZZOLO ACREIDE THEATER

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w11-475-2019 ◽

2019 ◽

Vol XLII-2/W11 ◽

pp. 475-479

Author(s):

G. Di Gregorio

Keyword(s):

Structure From Motion ◽

3D Model ◽

Southern Italy ◽

Three Dimensional ◽

Cultural Value ◽

Geometric Conditions ◽

Dense Matching ◽

Laser Scanners ◽

First Results ◽

Quality And Reliability

<p><strong>Abstract.</strong> The ancient theatres in Sicily, in southern Italy and along the countries facing the Mediterranean Sea basin, constitute a reality of incomparable cultural value. Regarding the research on the ancient theatres of eastern Sicily, few studies have been recently dealt with different methodologies. In the last years some practices have been done using 3D laser scanners for the theatres of Syracuse, Taormina and Morgantina, as well as the Syracuse amphitheatre and Taormina Odeon, just obtaining very interesting results. Lately the theatre of Palazzolo Acreide (Syracuse) has been studied, with Structure From Motion (SFM) and Dense Matching methodologies. From these experience, conclusions could be drawn on the quality and reliability of the elaborations realised with the SFM methodologies. We really know that these systems are today representing one of the fastest growing areas of examination, on which several software houses are investing. The study was chosen both for the small size of the building, and for the particular geometric conditions typical of the architecture of ancient theatres. This because their three-dimensional trend varies continually in the three variables X, Y, Z. The purpose of the work was to check whether the latest releases of these systems of survey allow today more than yesterday, a rapid digitalization and representation of the enormous archaeological cultural heritage. Various software were used, to verify the practicality and operation, the choice then fell on the Zephyr of 3DFlow, kindly available by the manufacturer, whose results were quite agreeable. The possibility offered by the program of a graphical tracing of polylines on the textured 3D model, has been a considerable advantage. Therefore the results obtained by modeling and surveying of the Palazzolo Acreide theatre have been compared, with the survey of the Syracuse, Taormina and Morgantina theatre performed using 3D laser scanners. First results of the research are matter of the following work.</p>

Download Full-text

Estimating Aboveground Biomass on Private Forest Using Sentinel-2 Imagery

Journal of Sensors ◽

10.1155/2018/6745629 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 6

Author(s):

Askar ◽

Narissara Nuthammachot ◽

Worradorn Phairuang ◽

Pramaditya Wicaksono ◽

Tri Sayektiningsih

Keyword(s):

Aboveground Biomass ◽

Vegetation Indices ◽

Forest Degradation ◽

Forest Monitoring ◽

Natural Forests ◽

Private Forests ◽

Indonesian Government ◽

Nations Programme ◽

Reduce Carbon Dioxide ◽

Sentinel 2

Private forests have a crucial role in maintaining the functioning of the Indonesian forest ecosystem especially because of the continuous degradation of natural forests. Private forests are a part of social forestry which becomes a tool for the Indonesian government to reduce carbon dioxide (CO2) emission by 26% by 2030. The United Nations Programme on Reducing Emissions from Deforestation and Forest Degradation has encouraged the Indonesian government to establish a forest monitoring system by estimating forest carbon stock using a combination of forest inventory and remote sensing. This study is aimed at assessing the potential of vegetation indices derived from Sentinel-2 for estimating aboveground biomass (AGB) of private forests. We used 45 sample plots and 7 vegetation indices to evaluate the ability of Sentinel-2 in estimating AGB on private forests. Normalised difference index (NDI) 45 exhibited a strong correlation with AGB compared to other indices (r = 0.89; R2 = 0.79). Stepwise linear regression fitted for establishing the model between field AGB and vegetation indices (R2 = 0.81). We also found that AGB in the study area based on spatial analysis was 72.54 Mg/ha. A root mean square error (RMSE) value from predicted and observed AGB was 27 Mg/ha. The AGB value in the study area is higher than the AGB value from some of forest types, and it indicates that private forests are good for biomass storage. Overall, vegetation indices from Sentinel-2 multispectral imagery can provide a good result in terms of reporting the AGB on private forests.

Download Full-text

Monitoring Pasture Aboveground Biomass and Canopy Height in an Integrated Crop–Livestock System Using Textural Information from PlanetScope Imagery

Remote Sensing ◽

10.3390/rs12162534 ◽

2020 ◽

Vol 12 (16) ◽

pp. 2534

Author(s):

Aliny A. Dos Reis ◽

João P. S. Werner ◽

Bruna C. Silva ◽

Gleyce K. D. A. Figueiredo ◽

João F. G. Antunes ◽

...

Keyword(s):

Aboveground Biomass ◽

Vegetation Indices ◽

Canopy Height ◽

Gradient Boosting ◽

Remotely Sensed Data ◽

Spatiotemporal Resolution ◽

Spectral Bands ◽

Extreme Gradient Boosting ◽

Intensively Managed ◽

New Generation

Fast and accurate quantification of the available pasture biomass is essential to support grazing management decisions in intensively managed fields. The increasing temporal and spatial resolutions offered by the new generation of orbital platforms, such as Planet CubeSat satellites, have improved the capability of monitoring pasture biomass using remotely sensed data. Here, we assessed the feasibility of using spectral and textural information derived from PlanetScope imagery for estimating pasture aboveground biomass (AGB) and canopy height (CH) in intensively managed fields and the potential for enhanced accuracy by applying the extreme gradient boosting (XGBoost) algorithm. Our results demonstrated that the texture measures enhanced AGB and CH estimations compared to the performance obtained using only spectral bands or vegetation indices. The best results were found by employing the XGBoost models based only on texture measures. These models achieved moderately high accuracy to predict pasture AGB and CH, explaining 65% and 89% of AGB (root mean square error (RMSE) = 26.52%) and CH (RMSE = 20.94%) variability, respectively. This study demonstrated the potential of using texture measures to improve the prediction accuracy of AGB and CH models based on high spatiotemporal resolution PlanetScope data in intensively managed mixed pastures.

Download Full-text

A PRACTICAL APPROACH FOR 3D BUILDING MODELING FROM UNCALIBRATED VIDEO SEQUENCES

International Journal of Image and Graphics ◽

10.1142/s0219467802000639 ◽

2002 ◽

Vol 02 (02) ◽

pp. 287-307 ◽

Cited By ~ 1

Author(s):

YONG LIU ◽

CHENG-KE WU ◽

HUNG-TAT TSUI

Keyword(s):

Structure From Motion ◽

3D Model ◽

Simulated Data ◽

Image Data ◽

Video Sequences ◽

Real Image ◽

Building Modeling ◽

Critical Configurations ◽

Motion Problem ◽

Fundamental Matrices

This paper presents an approach for reconstructing a realistic 3D model of a building from its uncalibrated video sequences taken by a hand-held camera. The novelty of this approach lies in the integration of some prior scene knowledge in the different stages of the Structure From Motion problem (SFM). First, the coplanarity of buildings is considered in the calculation of the fundamental matrices to deal with the critical configurations. Second, the line parallelism and plane orthogonality are transformed to the constraints on the absolute quadric during camera auto-calibration. This makes some critical cases solvable and the reconstruction more Euclidean. The approach is implemented and validated using simulated data and real image data. The experimental results at the end of the paper show the effectiveness of our approach.

Download Full-text