Stereo photogrammetry reveals substantial drag on cloud thermals

David M. Romps; Rusen Öktem

doi:10.1002/2015gl064009

Structure-from-motion, multi-view stereo photogrammetry applied to line-scan sediment core images

Journal of Paleolimnology ◽

10.1007/s10933-021-00204-x ◽

2021 ◽

Author(s):

Kévin Jacq ◽

Estelle Ployon ◽

William Rapuc ◽

Claire Blanchet ◽

Cécile Pignol ◽

...

Keyword(s):

Sediment Core ◽

Structure From Motion ◽

Line Scan ◽

Stereo Photogrammetry

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Comparison of Coniferous Plantation Heights Using Unmanned Aerial Vehicle (UAV) Laser Scanning and Stereo Photogrammetry

Remote Sensing ◽

10.3390/rs13152885 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2885

Author(s):

Mei Li ◽

Zengyuan Li ◽

Qingwang Liu ◽

Erxue Chen

Keyword(s):

Unmanned Aerial Vehicle ◽

Prediction Accuracy ◽

Laser Scanning ◽

Forest Stand ◽

Coniferous Plantation ◽

Point Density ◽

Stereo Photogrammetry ◽

Aerial Vehicle ◽

Stand Height ◽

Median Height

Plantation forests play a critical role in forest products and ecosystems. Unmanned aerial vehicle (UAV) remote sensing has become a promising technology in forest related applications. The stand heights will reflect the growth and competition of individual trees in plantation. UAV laser scanning (ULS) and UAV stereo photogrammetry (USP) can both be used to estimate stand heights using different algorithms. Thus, this study aimed to deeply explore the variations of four kinds of stand heights including mean height, Lorey’s height, dominated height, and median height of coniferous plantations using different models based on ULS and USP data. In addition, the impacts of thinned point density of 30 pts to 10 pts, 5 pts, 1 pts, and 0.8 pts/m2 were also analyzed. Forest stand heights were estimated from ULS and USP data metrics by linear regression and the prediction accuracy was assessed by 10-fold cross validation. The results showed that the prediction accuracy of the stand heights using metrics from USP was basically as good as that of ULS. Lorey’s height had the highest prediction accuracy, followed by dominated height, mean height, and median height. The correlation between height percentiles metrics from ULS and USP increased with the increased height. Different stand heights had their corresponding best height percentiles as variables based on stand height characteristics. Furthermore, canopy height model (CHM)-based metrics performed slightly better than normalized point cloud (NPC)-based metrics. The USP was not able to extract exact terrain information in a continuous coniferous plantation for forest canopy cover (CC) over 0.49. The combination of USP and terrain from ULS can be used to estimate forest stand heights with high accuracy. In addition, the estimation accuracy of each forest stand height was slightly affected by point density, which can also be ignored.

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Geometric Calibration of Digital Cameras for 3D Cumulus Cloud Measurements

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2008jtecha1079.1 ◽

2009 ◽

Vol 26 (2) ◽

pp. 200-214 ◽

Cited By ~ 12

Author(s):

Jiuxiang Hu ◽

Anshuman Razdan ◽

Joseph A. Zehnder

Keyword(s):

Field Measurements ◽

Geometric Error ◽

Digital Cameras ◽

Cumulus Clouds ◽

Geometric Calibration ◽

Earth Observing System ◽

Stereo Photogrammetry ◽

Camera Parameters ◽

The Right ◽

Coarse To Fine

Abstract A technique for calibrating digital cameras for stereo photogrammetry of cumulus clouds is presented. It has been applied to characterize the formation of summer thunderstorms observed during the Cumulus Photogrammetric, In Situ, and Doppler Observations (CuPIDO) project. Starting from gross measurements of locations, orientations of cameras, and landmark surveys, accurate locations and orientations of the cameras are obtained by minimizing a geometric error (GE). Once accurate camera parameters are obtained, 3D positions of cloud-feature points are computed by triangulation. The main contributions of this paper are as follows. First, it is proven that the GE has only one minimum in the neighborhood of the real parameters of a camera. In other words, searching the minimum of the GE enables the authors to find the right camera parameters even if there are significant differences between the initial measurements and their true values. Second, a new coarse-to-fine iterative algorithm is developed that minimizes the GE and finds the camera parameters. Numerical experiments show that the coarse-to-fine algorithm is efficient and effective. Third, a new landmark survey based on a geographic information system (GIS) rather than field measurements is presented. The GIS landmark survey is an effective and efficient way to obtain landmark world coordinates for camera calibrations in these experiments. Validation of this technique is achieved by the data collected by a NASA/Earth Observing System satellite and an instrumented aircraft. This paper builds on previous research and details the calibration and 3D reconstructions.

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Bioprosthetic heart valve leaflet motion monitored by dual camera stereo photogrammetry

Journal of Biomechanics ◽

10.1016/s0021-9290(99)00165-7 ◽

2000 ◽

Vol 33 (2) ◽

pp. 199-207 ◽

Cited By ~ 21

Author(s):

Zhi B. Gao ◽

Samir Pandya ◽

Nadeen Hosein ◽

Michael S. Sacks ◽

Ned H.C. Hwang

Keyword(s):

Heart Valve ◽

Valve Leaflet ◽

Bioprosthetic Heart Valve ◽

Stereo Photogrammetry ◽

Leaflet Motion

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Does the grey nurse shark (Carcharias taurus) exhibit agonistic pectoral fin depression? A stereo-video photogrammetric assessment off eastern Australia

Pacific Conservation Biology ◽

10.1071/pc15024 ◽

2016 ◽

Vol 22 (1) ◽

pp. 3

Author(s):

Kirby R. Smith ◽

Carol Scarpaci ◽

Brett M. Louden ◽

Nicholas M. Otway

Keyword(s):

Sampling Methods ◽

Pectoral Fin ◽

Nurse Shark ◽

Management Guidelines ◽

Life History Stages ◽

Stereo Video ◽

Eastern Australia ◽

Wide Range ◽

Stereo Photogrammetry ◽

Carcharias Taurus

Underwater stereo-video photogrammetry was used to document the pectoral fin positions of various life-history stages of the critically endangered east Australian population of the grey nurse shark (Carcharias taurus) during normal swimming behaviour at multiple aggregation sites. A wide range in pectoral fin positions was recorded with dihedral pectoral fin angles ranging from –25 to 88°. Pectoral fin angles varied significantly among sites and this was attributed to the differing navigational and energetic requirements of the sharks. There was no significant relationship between pectoral fin angles and distances separating the shark and scuba diver. The wide range in pectoral fin angles, interactive use of the fins during swimming, low-energy behaviours of the sharks at aggregation sites and absence of ‘fight’ response agonistic behaviour indicated that the species does not exhibit agonistic pectoral fin depression. Reports of agonistic pectoral fin depression in the grey nurse shark obtained with visual estimates should be treated as preliminary observations requiring further testing using accurate sampling methods such as stereo photogrammetry. It is important that diver compliance with existing management guidelines that prohibit divers from chasing or harassing grey nurse sharks and blocking cave and gutter entrances is maintained.

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Measurement of facial form using stereo-photogrammetry system.

THE JOURNAL OF THE STOMATOLOGICAL SOCIETY JAPAN ◽

10.5357/koubyou.54.605 ◽

1987 ◽

Vol 54 (3) ◽

pp. 605-610

Author(s):

Shunsuke Minakuchi ◽

Shuji Ando ◽

Shuji Kondo ◽

Toshiaki Sekita ◽

Ken'ichi Kobayashi ◽

...

Keyword(s):

Stereo Photogrammetry ◽

Facial Form

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Multiscale Very-High Resolution Topographic Models in Alpine Ecology: Pros and Cons of Airborne LiDAR and Drone-Based Stereo-Photogrammetry Technologies

10.20944/preprints202103.0581.v1 ◽

2021 ◽

Author(s):

Annie S. Guillaume ◽

Kevin Leempoel ◽

Estelle Rochat ◽

Aude Rogivue ◽

Michel Kasser ◽

...

Keyword(s):

Species Distribution Modelling ◽

Airborne Lidar ◽

Swiss Alps ◽

The Arctic ◽

Site Characteristics ◽

Digital Elevation ◽

Stereo Photogrammetry ◽

Arabis Alpina ◽

Western Swiss Alps ◽

Very High

The vulnerability of alpine environments to climate change presses an urgent need to accurately model and understand these ecosystems. Popularity in use of digital elevation models (DEMs) to derive proxy environmental variables has increased over the past decade, particularly as DEMs are relatively cheaply acquired at very high resolutions (VHR; <1m spatial resolution). Here, we implement a multiscale framework and compare DEM-derived variables produced by Light Detection and Ranging (LiDAR) and stereo-photogrammetry (PHOTO) methods, with the aims of assessing their relevance and utility in species distribution modelling (SDM). Using a case study on the arctic-alpine plant Arabis alpina in two valleys in the western Swiss Alps, we show that both LiDAR and PHOTO technologies can be relevant for producing DEM-derived variables for use in SDMs. We demonstrate that PHOTO DEMs rivalled the accuracy of LiDAR, putting the current paradigm of LiDAR being the more accurate of the two methods into question. We obtained DEMs at spatial resolutions of 6.25cm-8m for PHOTO and 50cm-32m for LiDAR, where we determined that the optimal spatial resolutions of DEM-derived variables in SDM were between 1 and 32m, depending on the variable and site characteristics. We found that the reduced extent of PHOTO DEMs altered the calculations of all derived variables, which had particular consequences on their relevance at the site with heterogenous terrain. However, for the homogenous site, we found that SDMs based on PHOTO-derived variables generally had higher predictive powers than those derived from LiDAR at matching resolutions. From our results, we recommend carefully considering the required DEM extent to produce relevant derived variables. We also advocate implementing a multiscale framework to appropriately assess the ecological relevance of derived variables, where we caution against the use of VHR-DEMs finer than 50cm in such studies.

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