Calibration of long focal length cameras in close range photogrammetry

Stamatopoulos, Christos; Fraser, Clive S.

doi:10.1111/j.1477-9730.2011.00648.x

Cited by 38 publications

(28 citation statements)

References 6 publications

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“…However, the narrow field of view of long focal length can impact adversely on the linear dependencies between the interior and exterior orientation parameters [45]. Although bundle adjustment convergences in the experiments, the results do not meet expectations.…”

Section: (3) Difference In Data Processingcontrasting

confidence: 45%

Scanning Photogrammetry for Measuring Large Targets in Close Range

et al. 2015

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Abstract:In close-range photogrammetry, images are difficult to acquire and organize primarily because of the limited field of view (FOV) of digital cameras when long focal lenses are used to measure large targets. To overcome this problem, we apply a scanning photography method that acquires images by rotating the camera in both horizontal and vertical directions at one station. This approach not only enlarges the FOV of each station but also ensures that all stations are distributed in order without coverage gap. We also conduct a modified triangulation according to the traits of the data overlapping among images from the same station to avoid matching all images with one another. This algorithm synthesizes the images acquired from the same station into synthetic images, which are then used to generate a free network. Consequently, we solve the exterior orientation elements of each original camera image in the free network and perform image matching among original images to obtain tie points. Finally, all original images are combined in self-calibration bundle adjustment with control points. The feasibility and precision of the proposed method are validated by testing it on two fields using 300 and 600 mm lenses. The results confirm that even with a small amount of control points, the developed scanning photogrammetry can steadily achieve millimeter scale accuracy at distances ranging from 40 m to 250 m.

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Section: (3) Difference In Data Processingcontrasting

confidence: 45%

Scanning Photogrammetry for Measuring Large Targets in Close Range

et al. 2015

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“…Some TL 2 measurements may have included the tip of the lower jaw, which would have resulted in slightly longer TL values. Alternatively, measurement error in TL 2 may be associated with barrel distortion at the edges of the digital images or with optical aberrations of the lens (Mallon and Whelan 2007;Stamatopoulos and Fraser 2011;Alemán-Flores et al 2014). Regardless of the cause, a systematic shift (inaccuracy) in a measurement can usually be fixed with calibration (Barnhart et al 2007); however, in our case, increased consistency and accuracy in the starting and stopping points of photogrammetric measurements would likely remove this bias.…”

Section: Accuracy Precision and Error In Photogrammetric Measurementsmentioning

confidence: 92%

A Semi‐Automated Method for Monitoring Dam Passage of Upstream Migrant Yellow‐Phase American Eels

Welsh

Aldinger

2014

N American J Fish Manag

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Fish passage facilities at dams have become an important focus of fishery management in riverine systems. Given the personnel and travel costs associated with physical monitoring programs, automated or semi‐automated systems are an attractive alternative for monitoring fish passage facilities. We designed and tested a semi‐automated system for eel ladder monitoring at Millville Dam on the lower Shenandoah River, West Virginia. A motion‐activated eel ladder camera (ELC) photographed each yellow‐phase American Eel Anguilla rostrata that passed through the ladder. Digital images (with date and time stamps) of American Eels allowed for total daily counts and measurements of eel TL using photogrammetric methods with digital imaging software. We compared physical counts of American Eels with camera‐based counts; TLs obtained with a measuring board were compared with TLs derived from photogrammetric methods. Data from the ELC were consistent with data obtained by physical methods, thus supporting the semi‐automated camera system as a viable option for monitoring American Eel passage. Time stamps on digital images allowed for the documentation of eel passage time—data that were not obtainable from physical monitoring efforts. The ELC has application to eel ladder facilities but can also be used to monitor dam passage of other taxa, such as crayfishes, lampreys, and water snakes. Received December 31, 2013; accepted March 11, 2014

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“…The narrow angle of view, coming close to a parallel projection, is proven to benefit from modified cameras models, such as the use of expanded partial derivative expressions for the principal point (Stamatopoulos et al 2011). In this case no special constraints were found to be necessary to accommodate the long focal length of the Kern lens.…”

Section: Network Adjustmentsmentioning

confidence: 99%

Close Range Calibration of Long Focal Length Lenses in a Changing Environment

Robson

MacDonald

Kyle

et al. 2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:University College London is currently developing a large-scale multi-camera system for dimensional control tasks in manufacturing, including part machining, assembly and tracking, as part of the Light Controlled Factory project funded by the UK Engineering and Physical Science Research Council. In parallel, as part of the EU LUMINAR project funded by the European Association of National Metrology Institutes, refraction models of the atmosphere in factory environments are being developed with the intent of modelling and eliminating the effects of temperature and other variations. The accuracy requirements for both projects are extremely demanding, so accordingly improvements in the modelling of both camera imaging and the measurement environment are essential. At the junction of these two projects lies close range camera calibration. The accurate and reliable calibration of cameras across a realistic range of atmospheric conditions in the factory environment is vital in order to eliminate systematic errors. This paper demonstrates the challenge of experimentally isolating environmental effects at the level of a few tens of microns. Longer lines of sight promote the use and calibration of a near perfect perspective projection from a Kern 75mm lens with maximum radial distortion of the order of 0.5m. Coordination of a reference target array, representing a manufactured part, is achieved to better than 0.1mm at a standoff of 8m. More widely, results contribute to better sensor understanding, improved mathematical modelling of factory environments and more reliable coordination of targets to 0.1mm and better over large volumes.

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Calibration of long focal length cameras in close range photogrammetry

Cited by 38 publications

References 6 publications

Scanning Photogrammetry for Measuring Large Targets in Close Range

Scanning Photogrammetry for Measuring Large Targets in Close Range

A Semi‐Automated Method for Monitoring Dam Passage of Upstream Migrant Yellow‐Phase American Eels

Close Range Calibration of Long Focal Length Lenses in a Changing Environment

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