Performance evaluation of thermographic cameras for photogrammetric documentation of historical buildings

Thermographic cameras record temperatures emitted by objects in the infrared region. These thermal images can be used for texture analysis and deformation caused by moisture and isolation problems. For accurate geometric survey of the deformations, the geometric calibration and performance evaluation of the thermographic camera should be conducted properly. In this study, an approach is proposed for the geometric calibration of the thermal cameras for the geometric survey of deformation caused by moisture. A 3D test object was designed and used for the geometric calibration and performance evaluation. The geometric calibration parameters, including focal length, position of principal point, and radial and tangential distortions, were determined for both the thermographic and the digital camera. The digital image rectification performance of the thermographic camera was tested for photogrammetric documentation of deformation caused by moisture. The obtained results from the thermographic camera were compared with the results from digital camera based on the experimental investigation performed on a study area.

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On-Sun Evaluation of the PHLUX Method for Heliostat Beam Characterization

Volume 1: Biofuels, Hydrogen, Syngas, and Alternate Fuels; CHP and Hybrid Power and Energy Systems; Concentrating Solar Power; Energy Storage; Environmental, Economic, and Policy Considerations of Advanced Energy Systems; Geothermal, Ocean, and Emerging Energy Technologies; Photovoltaics; Posters; Solar Chemistry; Sustainable Building Energy Systems; Sustainable Infrastructure and Transportation; Thermodynamic Analysis of Energy Systems; Wind Energy Systems and Technologies ◽

10.1115/es2016-59409 ◽

2016 ◽

Author(s):

Julius Yellowhair ◽

Clifford K. Ho

Keyword(s):

Focal Length ◽

Digital Camera ◽

Total Power ◽

Neutral Density ◽

Additional Information ◽

Direct Normal Irradiance ◽

Beam Characterization ◽

Peak Flux ◽

And Performance ◽

Solar Field

Flux distributions from solar field collectors are typically evaluated using a beam characterization system, which consists of a digital camera with neutral density filters, flux gauge or calorimeter, and water-cooled Lambertian target panel. The pixels in camera image of the flux distribution are scaled by the flux peak value measured with the flux gauge or the total power value measured with the calorimeter. An alternative method, called PHLUX developed at Sandia National Laboratories, can serve the same purpose using a digital camera but without auxiliary instrumentation. The only additional information required besides the digital images recorded from the camera are the direct normal irradiance, an image of the sun using the same camera, and the reflectivity of the receiver or target panel surface. The PHLUX method was evaluated using two digital cameras (Nikon D90 and D3300) at different flux levels on a target panel. The performances of the two cameras were compared to each other and to measurements from a Kendall radiometer. For consistency in comparison of the two cameras, the same focal length lenses and same number of neutral density filters were used. Other camera settings (e.g., shutter speed, f-stop, etc.) were set based on the aperture size and performance of the cameras. The Nikon D3300 has twice the number of pixels as the D90. D3300 provided higher resolution, however, due to the smaller pixel sizes the images were noisier, and the D90 with larger pixels had better response to low light levels. The noise in the D3300, if not corrected, could result in gross overestimation of the irradiance calculations. After corrections to the D3300 flux images, the PHLUX results from the two cameras showed they agreed to within 8% for a peak flux level of 1000 suns on the target, and less than 10% error in the peak flux when compared to the Kendall radiometer.

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Preparation of Sb:F:SnO2 Films and their Application in Low-E Glass

Materials Science Forum ◽

10.4028/www.scientific.net/msf.620-622.5 ◽

2009 ◽

Vol 620-622 ◽

pp. 5-8 ◽

Cited By ~ 3

Author(s):

Gao Yang Zhao ◽

Xiao Zhi ◽

Yang Ren ◽

Tao Zhu

Keyword(s):

Thin Films ◽

Performance Evaluation ◽

Tin Oxide ◽

Quantitative Relationship ◽

Far Infrared ◽

Infrared Region ◽

Infrared Reflectance ◽

Spray Volume ◽

And Performance ◽

Conductive Thin Films

In this paper, fluorine & antimony-doped tin oxide (FATO) transparent conductive thin films are deposited by Spray Pyrolysis on glass substrate, and low emissivity properties achieved. The emissivity of glass in far infrared region is optimized by changing the spray volume, the resistivity and sheet resistance of thin films. Research shows that the resistivity of thin films has important influence on infrared reflectance and hemispheric emissivity. This paper further investigates the quantitative relationship between emissivity and resistivity of low-E glass and also provides a basis for emissivity control and performance evaluation of Low-E glass.

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Assessing a 35mm Fixed-Lens Sony Alpha-5100 Intrinsic Parameters Prior to, During, and Post UAV Flight Mission

KnE Engineering ◽

10.18502/keg.v4i3.5887 ◽

2019 ◽

Author(s):

Martinus E Tjahjadi ◽

Silvester S Sai ◽

Fourry Handoko

Keyword(s):

Aerial Photography ◽

Focal Length ◽

Digital Camera ◽

Optical Quality ◽

Bundle Adjustment ◽

Principal Point ◽

Intrinsic Parameters ◽

Stability Performance ◽

Focal Length Lens ◽

Cmos Sensor

A fixed focal length lens (FFL) camera with on-adjustable focal length is common companions for conducting aerial photography using unmanned aerial vehicles (UAVs) due to its superiority on optical quality and wider maximum aperture, lighter weight and smaller sizes. A wide-angle 35mm FFL Sony a5100 camera had been used extensively in our recent aerial photography campaign using UAV. Since this off-the-self digital camera is categorized into a non-metric one, a stability performance issue in terms of intrinsic parameters raises a considerably attention, particularly on variations of the lens principal distance and principal point’s position relative to the camera’s CCD/CMOS sensor caused by the engine and other vibrations during flight data acquisitions. A series of calibration bundle adjustment was conducted to determine variations in the principal distances and principal point coordinates before commencing, during, and after accomplishment of the flight missions. This paper demonstrates the computation of the parameters and presents the resulting parameters for three different epochs. It reveals that there are distinct discrepancies of the principal distances and principal point coordinates prior to, during, and after the mission, that peaked around 1.2mm for the principal distance, as well as around 0.4mm and 1.3mm along the x-axis and the y-axis of the principal point coordinates respectively. In contrast, the lens distortions parameters show practically no perturbations in terms of radial, decentering, and affinity distortion terms during the experiments.

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