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1
Dedei Tagoe, Naa, and S. Mantey. "Determination of the Interior Orientation Parameters of a Non-metric Digital Camera for Terrestrial Photogrammetric Applications." Ghana Mining Journal 19, no. 2 (December 22, 2019): 1–9. http://dx.doi.org/10.4314/gm.v19i2.1.
Повний текст джерелаАнотація:
AbstractHigh cost of metric photogrammetric cameras has given rise to the utilisation of non-metric digital cameras to generate photogrammetric products in traditional close range or terrestrial photogrammetric applications. For precision photogrammetric applications, the internal metric characteristics of the camera, customarily known as the Interior Orientation Parameters, need to be determined and analysed. The derivation of these parameters is usually achieved by implementing a bundle adjustment with self-calibration procedure. The stability of the Interior Orientation Parameters is an issue in terms of accuracy in digital cameras since they are not built with photogrammetric applications in mind. This study utilised two photogrammetric software (i.e. Photo Modeler and Australis) to calibrate a non-metric digital camera to determine its Interior Orientation Parameters. The camera parameters were obtained using the two software and the Root Mean Square Errors (RMSE) calculated. It was observed that Australis gave a RMSE of 0.2435 and Photo Modeler gave 0.2335, implying that, the calibrated non-metric digital camera is suitable for high precision terrestrial photogrammetric projects. Keywords: Camera Calibration, Interior Orientation Parameters, Non-Metric Digital Camera
2
Du, Ye Fei, Ming Li Dong, Jun Wang, and Peng Sun. "A Method Based on Two Constraints for Camera Calibration Interior Parameters." Applied Mechanics and Materials 103 (September 2011): 181–86. http://dx.doi.org/10.4028/www.scientific.net/amm.103.181.
Повний текст джерелаАнотація:
In the digital photogrammetry system, camera calibration is an essential part and its accuracy directly affects system accuracy. Because non-metric digital camera interior parameters are the stationary in the measurement process, the camera interior parameters should be accurately calibrated in the laboratory. Considering the lack of general DLT algorithm, we adopt nonlinear model of the camera based on distortion. And two additional constraints are used to accurately calibrate the parameters of the camera. The experimental results are analyzed and compared with the V-STARS system. The results of interior parameters calibration are less than 1 pixel. Test results meet the requirements of industrial digital photogrammetry.
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Chibunichev, A. G., A. V. Govorov, and V. E. Chernyshev. "RESEARCH OF THE CAMERA CALIBRATION USING SERIES OF IMAGES WITH COMMON CENTER OF PROJECTION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W18 (November 29, 2019): 19–22. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w18-19-2019.
Повний текст джерелаАнотація:
Abstract. The method for calibration of cameras equipped with long focal distance lens is researched in the present work. The basic idea is as follows. The camera to be calibrated is placed on the tripod with panoramic head. The main condition of panorama shooting is that the rotation center of the camera and the front nodal point of the lens should be the same. The camera is calibrated based on a series of images of a test object with a common center of projection. Special software has been created for this purpose. The results of experimental studies on digital simulated data and for a real camera Hasselblad H4D-60 are presented. Results of these experiments show that use of common projection center allow to increase accuracy of the calibration process of the long focal length cameras.
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Dymond, John R., and Craig M. Trotter. "Directional reflectance of vegetation measured by a calibrated digital camera." Applied Optics 36, no. 18 (June 20, 1997): 4314. http://dx.doi.org/10.1364/ao.36.004314.
Повний текст джерела
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Ye, J. F., and J. R. Tsay. "WAVELETS FOR SELF-CALIBRATED BUNDLE BLOCK ADJUSTMENT." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B1-2020 (August 6, 2020): 407–14. http://dx.doi.org/10.5194/isprs-archives-xliii-b1-2020-407-2020.
Повний текст джерелаАнотація:
Abstract. This paper entails a methodological novelty and builds upon prior research on a wavelets-based model for digital camera self-calibration. We introduce a new kernel function based on the compactly supported orthogonal third-order asymmetric Daubechies wavelet to correct systematic image distortion errors. Tests are done by using aerial images taken with a high-resolution metric digital aerial mapping camera. The quality of experimental results is evaluated by using reliable and high precision ground check points in the calibration field. For example, a four-fold block with this wavelet self-calibration model has the external accuracy of about 0.28 GSD (=ground sampling distance) in the horizontal direction, and about 0.43 GSD in the vertical direction, respectively, where 1GSD ≈ 4.6cm. The posterior standard deviations σ̂0 of unit weight are reduced from 0.37 pixel to 0.27 pixel. The residual vector lengths are also significantly reduced after our wavelet additional parameters are used. Experimental results support the proposal and demonstrate the applicability of this new model.
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Sužiedelytė-Visockienė, Jūratė. "PHOTOGRAMMETRY REQUIREMENTS FOR DIGITAL CAMERA CALIBRATION APPLYING TCC AND MATLAB SOFTWARE." Geodesy and Cartography 38, no. 3 (October 1, 2012): 106–10. http://dx.doi.org/10.3846/20296991.2012.728895.
Повний текст джерелаАнотація:
The result of photogrammetry is a digital object or terrain images on the plane or in three-dimensional space. Precise data on the object is photocopied by a professional digital camera equipped with the calibrated system of optical lens (evaluation of distortion parameters for optical lens). Camera calibration is performed in a laboratory or employing special calibration software and using special field testing. However, Lithuania doesn't own similar laboratories. Therefore, an important point is obtaining proper software for the verification of these works. European countries have been using plenty of various software and different test field calibration (plate), including two-dimensional, three-dimensional, etc. Therefore, choosing the simplest, cheapest and most acceptable method of camera calibration is essential. Research was made applying the Canon EOS-1D Mark II (resolution - 21 million points, with the focal length of the lens reaching 21 mm). The optical system was calibrated using Tcc (Germany) and MatLab software. The calibration processes were done taking a different test field of camera calibration. The article analyzes calibration results and offers suggestions on camera calibration.
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Xia, Peng, Qinghua Wang, Shien Ri, and Hiroshi Tsuda. "Calibrated phase-shifting digital holography based on a dual-camera system." Optics Letters 42, no. 23 (November 28, 2017): 4954. http://dx.doi.org/10.1364/ol.42.004954.
Повний текст джерела
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Teo, T. "VIDEO-BASED POINT CLOUD GENERATION USING MULTIPLE ACTION CAMERAS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-4/W5 (May 11, 2015): 55–60. http://dx.doi.org/10.5194/isprsarchives-xl-4-w5-55-2015.
Повний текст джерелаАнотація:
Due to the development of action cameras, the use of video technology for collecting geo-spatial data becomes an important trend. The objective of this study is to compare the image-mode and video-mode of multiple action cameras for 3D point clouds generation. Frame images are acquired from discrete camera stations while videos are taken from continuous trajectories. The proposed method includes five major parts: (1) camera calibration, (2) video conversion and alignment, (3) orientation modelling, (4) dense matching, and (5) evaluation. As the action cameras usually have large FOV in wide viewing mode, camera calibration plays an important role to calibrate the effect of lens distortion before image matching. Once the camera has been calibrated, the author use these action cameras to take video in an indoor environment. The videos are further converted into multiple frame images based on the frame rates. In order to overcome the time synchronous issues in between videos from different viewpoints, an additional timer APP is used to determine the time shift factor between cameras in time alignment. A structure form motion (SfM) technique is utilized to obtain the image orientations. Then, semi-global matching (SGM) algorithm is adopted to obtain dense 3D point clouds. The preliminary results indicated that the 3D points from 4K video are similar to 12MP images, but the data acquisition performance of 4K video is more efficient than 12MP digital images.
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Govorov, A. V., A. G. Chibunichev, and S. B. Makarov. "STUDY OF DIGITAL CAMERA CALIBRATION ON A FLAT TEST OBJECT." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2020 (August 12, 2020): 29–33. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2020-29-2020.
Повний текст джерелаАнотація:
Abstract. The paper presents a method for calibration of digital cameras based on the use of a flat test object. The main distinctive feature of this method is that the camera is fixed and does not change its position in space. A series of images of a flat test object (for example, a chessboard) is taken at various distances and inclination of the test object. One should tilt the test object relative to the image plane in order to avoid ambiguity in solving the problem. All these images are measured separately, and processing is performed together, counting them as one image with common exterior orientation elements. Experimental studies have shown sufficient efficiency of such calibration, which is easily implemented and gives positive results in comparison with the classical calibration of the camera on a spatial test object. The results of experimental studies on real images have shown that proposed calibration method gives the comparable with conventional method accuracy. Thus, it is possible to use simple and cheap flat calibration test object instead of spatial one. To achieve the maximum result in camera calibration accuracy, use this method to tilt the chessboard at angles in the range of 30–40 degrees to the optical axis of the camera being calibrated.
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Kolláth, Zoltán, and Anita Dömény. "Night sky quality monitoring in existing and planned dark sky parks by digital cameras." International Journal of Sustainable Lighting 19, no. 1 (June 28, 2017): 61–68. http://dx.doi.org/10.26607/ijsl.v19i1.70.
Повний текст джерелаАнотація:
A crucial part of the qualification of international dark sky places (IDSPs) is the objective measurement of night time sky luminance or radiance. Modern digital cameras provide an alternative way to perform all sky imaging either by a fisheye lens or by a mosaic image taken by a wide angle lens. Here we present a method for processing raw camera images to obtain calibrated measurements of sky quality. The comparison of the night sky quality of different European locations is also presented to demonstrate the use of our technique.
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Sheng, Ding Yi, Shen Peng Li, Zai Yuan Wang, and Jing Zhang. "Distortion Calibration for Camera Lens Based on Digital Image Processing." Advanced Materials Research 926-930 (May 2014): 1530–33. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.1530.
Повний текст джерелаАнотація:
Distortion produced by optical system makes the image of object in linear CCD deviate from the theoretical point and lead to the system measuring error. According to the digital image processing, a high-precision calibration method is proposed. The imaging measurement system is calibrated through two steps: firstly, use laser collimation to detect the principal point for a large visal field camera lens with short focal distance. Secondly, use a rectangular gidding target to get lens distortion coefficient.
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Ataiwe, Tariq N., Israa Hatem, and Hisham M. J. Al Sharaa. "Digital Model in Close-Range Photogrammetry Using a Smartphone Camera." E3S Web of Conferences 318 (2021): 04005. http://dx.doi.org/10.1051/e3sconf/202131804005.
Повний текст джерелаАнотація:
Smartphones recently expanded the potential for low-cost close-range photogrammetry for 3D modeling. They enable the simultaneous collection of large amounts of data for a variety of requirements. It is possible to calculate image orientation elements and triangular coordinates in phases as in Relative and Absolute image orientation. This study demonstrates the photogrammetric 3D reconstruction approach that performs on tablets and smartphones as well. Images are taken with smartphone cameras of iPhone 6 and then calibrated automatically using normal calibration model for photogrammetry and computer vision on a PC, depend on Agisoft Lens add-on that imbedded in Agisoft program, and MATLAB camera calibration Toolbox, and by using an oriented bunch of images of chessboard pattern for large point cloud-based picture using matching. The camera calibration results indicate that the calibration processing routines pass without any error, and the accuracy of estimated IOPs was convenient compared with non-metric digital cameras and are more accurate in Agisoft Lens in terms of standard error. For the 3D model, 435 cameras were used, 428 cameras located from 435 are aligned in two photogrammetric software, Agisoft PhotoScan, and LPS. The number of tie points that are used in LPS is 10 tie points, and 4 control points which used to estimate the EOPs, and the number of tie points that are regenerated in Agisoft PhotoScan were 135.605 points, the number of Dense cloud 3,716,912 points are generated, for 3D model a number of 316,253 faces are generated, after processing the tiled model generated (6 levels, 1.25 cm/pix), the generated DEM having (2136×1774/pix), the dimensions of the generated high-resolution orthomosaic are (5520×4494, 4.47 cm/pix). For accuracy assessment, the Xerr. = 0.292 m, Yerr. = 0.38577 m, Zerr.= 0.2889 m, and the total RMS = 0.563 m in the estimated locations of the exterior orientation parameters.
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Yaron, Yaron, Eran Keinan, Moshe Benhamu, Ronen Regev, and Garry Zalmanzon. "NATIONAL GUIDELINES FOR DIGITAL CAMERA SYSTEMS CERTIFICATION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B1 (June 3, 2016): 179–84. http://dx.doi.org/10.5194/isprsarchives-xli-b1-179-2016.
Повний текст джерелаАнотація:
Digital camera systems are a key component in the production of reliable, geometrically accurate, high-resolution geospatial products. These systems have replaced film imaging in photogrammetric data capturing. Today, we see a proliferation of imaging sensors collecting photographs in different ground resolutions, spectral bands, swath sizes, radiometric characteristics, accuracies and carried on different mobile platforms. In addition, these imaging sensors are combined with navigational tools (such as GPS and IMU), active sensors such as laser scanning and powerful processing tools to obtain high quality geospatial products. The quality (accuracy, completeness, consistency, etc.) of these geospatial products is based on the use of calibrated, high-quality digital camera systems. <br><br> The new survey regulations of the state of Israel specify the quality requirements for each geospatial product including: maps at different scales and for different purposes, elevation models, orthophotographs, three-dimensional models at different levels of details (LOD) and more. In addition, the regulations require that digital camera systems used for mapping purposes should be certified using a rigorous mapping systems certification and validation process which is specified in the Director General Instructions. The Director General Instructions for digital camera systems certification specify a two-step process as follows: <br><br> 1. Theoretical analysis of system components that includes: study of the accuracy of each component and an integrative error propagation evaluation, examination of the radiometric and spectral response curves for the imaging sensors, the calibration requirements, and the working procedures. <br><br> 2. Empirical study of the digital mapping system that examines a typical project (product scale, flight height, number and configuration of ground control points and process). The study examine all the aspects of the final product including; its accuracy, the product pixels size on the ground (spatial resolution), its completeness (missing pixels and striping affect), its radiometric properties (e.g., relative edge response) and its spectral characteristics (e.g., histogram spread, bands misalignment). <br><br> This methodology was tested on a number of medium to large format digital cameras. The certification process is a basic stage in the mapping chain in Israel. This article provides the details of the Director General Instructions for digital camera systems certification, the methodology for certification and the tests that were carried out.
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Yaron, Yaron, Eran Keinan, Moshe Benhamu, Ronen Regev, and Garry Zalmanzon. "NATIONAL GUIDELINES FOR DIGITAL CAMERA SYSTEMS CERTIFICATION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B1 (June 3, 2016): 179–84. http://dx.doi.org/10.5194/isprs-archives-xli-b1-179-2016.
Повний текст джерелаАнотація:
Digital camera systems are a key component in the production of reliable, geometrically accurate, high-resolution geospatial products. These systems have replaced film imaging in photogrammetric data capturing. Today, we see a proliferation of imaging sensors collecting photographs in different ground resolutions, spectral bands, swath sizes, radiometric characteristics, accuracies and carried on different mobile platforms. In addition, these imaging sensors are combined with navigational tools (such as GPS and IMU), active sensors such as laser scanning and powerful processing tools to obtain high quality geospatial products. The quality (accuracy, completeness, consistency, etc.) of these geospatial products is based on the use of calibrated, high-quality digital camera systems. <br><br> The new survey regulations of the state of Israel specify the quality requirements for each geospatial product including: maps at different scales and for different purposes, elevation models, orthophotographs, three-dimensional models at different levels of details (LOD) and more. In addition, the regulations require that digital camera systems used for mapping purposes should be certified using a rigorous mapping systems certification and validation process which is specified in the Director General Instructions. The Director General Instructions for digital camera systems certification specify a two-step process as follows: <br><br> 1. Theoretical analysis of system components that includes: study of the accuracy of each component and an integrative error propagation evaluation, examination of the radiometric and spectral response curves for the imaging sensors, the calibration requirements, and the working procedures. <br><br> 2. Empirical study of the digital mapping system that examines a typical project (product scale, flight height, number and configuration of ground control points and process). The study examine all the aspects of the final product including; its accuracy, the product pixels size on the ground (spatial resolution), its completeness (missing pixels and striping affect), its radiometric properties (e.g., relative edge response) and its spectral characteristics (e.g., histogram spread, bands misalignment). <br><br> This methodology was tested on a number of medium to large format digital cameras. The certification process is a basic stage in the mapping chain in Israel. This article provides the details of the Director General Instructions for digital camera systems certification, the methodology for certification and the tests that were carried out.
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Yilmazturk, Ferruh, and Ali Ersin Gurbak. "Geometric Evaluation of Mobile-Phone Camera Images for 3D Information." International Journal of Optics 2019 (September 30, 2019): 1–10. http://dx.doi.org/10.1155/2019/8561380.
Повний текст джерелаАнотація:
This study aimed to investigate the usability of smartphone camera images in 3D positioning applications with photogrammetric techniques. These investigations were performed in two stages. In the first stage, the cameras of five smartphones and a digital compact camera were calibrated using a calibration reference object, with signalized points having known three-dimensional (3D) coordinates. In the calibration process, the self-calibration bundle adjustment method was used. To evaluate the metric performances, the geometric accuracy tests in the image and object spaces were performed and the test results were compared. In the second stage, a 3D mesh model of a historical cylindrical structure (height = 8 m and diameter = 5 m) was generated using Structure-from-Motion and Multi-View-Stereo (SfM-MVS) approach. The images were captured using the Galaxy S4 smartphone camera, which produced the best result in the geometric accuracy tests for smartphone cameras. The accuracy tests on the generated 3D model were also applied in order to examine 3D object reconstruction capabilities of imaging with this device. The results demonstrated that smartphone cameras can be easily used as image acquisition tools for multiple photogrammetric applications.
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Shih, Ming Hsiang, Wen Pei Sung, and Darius Bacinskas. "Development of Digital Imagine Correlation (DIC) Method for Three-Dimensional Rugged Surface of Construction Material." Advanced Materials Research 243-249 (May 2011): 5907–10. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.5907.
Повний текст джерелаАнотація:
Digital Image Correlation, DIC method is developed a low-cost digital image correlation coefficient method based on advanced digital cameras and high-speed computers. Traditionally, two or more cameras are widely applied for conducting 3-D monitoring. There are numerous parameters need to be accurately calibrated. Therefore, the results of 3-D accuracy are worse than that of 2-D accuracy. The feasibility of a single camera to collect image to analyze the three-dimensional rugged surface of material is proposed in this study. A three-dimensional facial mask-like human makeup test and plaster cast are used to test. The test results reveal that the coordinate error between these two photos of the three-dimensional facial mask-like human makeup test is only 0.002mm and the absolute displacement, rotate on z-axis, strain on z-axis and von Mises strain of analysis results are extremely close to the real surface plaster cast.
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Lichti, D. D., D. Jarron, M. Shahbazi, P. Helmholz, and R. Radovanovic. "INVESTIGATION INTO THE BEHAVIOUR AND MODELLING OF CHROMATIC ABERRATIONS IN NON-METRIC DIGITAL CAMERAS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W18 (November 29, 2019): 99–106. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w18-99-2019.
Повний текст джерелаАнотація:
Abstract. Chromatic aberration in colour digital camera imagery can affect the accuracy of photogrammetric reconstruction. Both longitudinal and transverse chromatic aberrations can be effectively modelled by making separate measurements in each of the blue, green and red colour bands and performing a specialized self-calibrating bundle adjustment. This paper presents the results of an investigation with two aims. The first aim is to quantify the presence of chromatic aberration in two sets of cameras: the six individual cameras comprising a Ladybug5 system, calibrated simultaneously in air; and four GoPro Hero 5 cameras calibrated independently under water. The second aim is to investigate the impacts of imposing different constraints in the self-calibration adjustment. To this end, four different adjustment cases were performed for all ten cameras: independent adjustment of the observations from each colour band; combined adjustment of all colour bands’ observations with common object points; combined adjustment of all colour bands with common object points and common exterior orientation parameters for each colour band triplet; and combined adjustment with common object points and certain common interior orientation parameters. The results show that the Ladybug5 cameras exhibit a small (1-2 pixel) amount of transverse chromatic aberration but no longitudinal chromatic aberration. The GoPro Hero 5 cameras exhibit significant (25 pixel) transverse chromatic aberration as well as longitudinal chromatic aberration. The principal distance was essentially independent of the adjustment case for the Ladybug5, but it was not for the GoPro Hero 5. The principal point position and precision were both affected considerably by adjustment case. Radial lens distortion was invariant to the adjustment case. The impact of adjustment case on decentring distortion was minimal in both cases.
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Kelly, Julia, Natascha Kljun, Per-Ola Olsson, Laura Mihai, Bengt Liljeblad, Per Weslien, Leif Klemedtsson, and Lars Eklundh. "Challenges and Best Practices for Deriving Temperature Data from an Uncalibrated UAV Thermal Infrared Camera." Remote Sensing 11, no. 5 (March 8, 2019): 567. http://dx.doi.org/10.3390/rs11050567.
Повний текст джерелаАнотація:
Miniaturized thermal infrared (TIR) cameras that measure surface temperature are increasingly available for use with unmanned aerial vehicles (UAVs). However, deriving accurate temperature data from these cameras is non-trivialsince they are highly sensitive to changes in their internal temperature and low-cost models are often not radiometrically calibrated. We present the results of laboratory and field experiments that tested the extent of the temperature-dependency of a non-radiometric FLIR Vue Pro 640. We found that a simple empirical line calibration using at least three ground calibration points was sufficient to convert camera digital numbers to temperature values for images captured during UAV flight. Although the camera performed well under stable laboratory conditions (accuracy ±0.5 °C), the accuracy declined to ±5 °C under the changing ambient conditions experienced during UAV flight. The poor performance resulted from the non-linear relationship between camera output and sensor temperature, which was affected by wind and temperature-drift during flight. The camera’s automated non-uniformity correction (NUC) could not sufficiently correct for these effects. Prominent vignetting was also visible in images captured under both stable and changing ambient conditions. The inconsistencies in camera output over time and across the sensor will affect camera applications based on relative temperature differences as well as user-generated radiometric calibration. Based on our findings, we present a set of best practices for UAV TIR camera sampling to minimize the impacts of the temperature dependency of these systems.
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Sukor, Syafiq, and Anuar Ahmad. "Evaluation of Low Cost Digital Cameras for Producing Photogrammetric Output from UAV." International Journal of Engineering & Technology 7, no. 2.29 (May 22, 2018): 792. http://dx.doi.org/10.14419/ijet.v7i2.29.14258.
Повний текст джерелаАнотація:
Recently there a lot of improvement in digital photogrammetry and this allow photogrammetry to become faster and cheaper . This study discuss about two type of low cost camera which is the compact camera (Canon Power Shot SX230 ) and action camera (Xiaomi yi) where both of them have different lens distortion. This study is conducted within UTM (Universiti Teknologi Malaysia) Skudai campus at Kolej Tun Razak. Both of the Canon Power Shot SX230 and Xiaomi yi camera would be attach to the UAV to take aerial photo with three different altitude which is 60 meter, 80 meter and 100 meter with a similar flight path. Check point (CPs) and Ground control point (GCPs) were also established using rapid static technique of Global Positioning System (GPS) and Total Station. The Canon Power Shot SX230 and Xiaomi yi camera is then calibrated using checkboard calibration this is done by using Agisoft Lens software. Then all of the pictures that been taken by the Canon Power Shot SX230 and the Xiaomi yi would be processed by using Agisoft Photoscan software to generate Digital Elevation Model (DEM), orthophoto and contour line. The accuracy of DEM was determined based on Root Mean Squared Error (RMSE) value. Both of the result is then analyze visually and statically. Overall both of the camera gives a slight different in accuracy.
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Kolláth, Zoltán, Dénes Száz, Kornél Kolláth, and Kai Pong Tong. "Light Pollution Monitoring and Sky Colours." Journal of Imaging 6, no. 10 (October 5, 2020): 104. http://dx.doi.org/10.3390/jimaging6100104.
Повний текст джерелаАнотація:
The measurement of night sky quality has become an important task in nature conservation. The primary device used for this task can be a calibrated digital camera. In addition, colour information can be derived from sky photography. In this paper, we provide a test on a concept to gather information about the possible sources of night sky brightness based on digital camera images. This method helps to understand changes in night sky quality due to natural and artificial changes in the environment. We demonstrate that a well-defined colour–colour diagram can differentiate between the different natural and artificial sources of night sky radiance. The colour information can be essential when interpreting long-term evolution of light pollution measurements.
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Yang, Biao, Ming Fei Wu, and Hao Li. "A Rapid Reserve Inspection Method for Opencast Mine Using Ordinary Digital Camera." Applied Mechanics and Materials 333-335 (July 2013): 1533–37. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.1533.
Повний текст джерелаАнотація:
Reserve inspection is of great significance for rational mining and environmental protection of opencast mine. This paper proposes a method for rapid reserve inspection of opencast mine. The method uses ordinary digital camera which is calibrated rigorously to acquire images of opencast mine, and carries out a series of image processing steps including distortion correction, relative orientation, absolute orientation and stereo matching, thus generating the point cloud and reconstructing the three-dimensional mine model. According to the earlier topographic and design data, the variations of mine surface, volume and reserve are thereby calculated. The practical application of the method proposed has achieved great improvement in efficiency and accuracy for opencast mine reserve inspection.
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Kretkowski, M., Ryszard Jabłoński, and Y. Shimodaira. "Color Calibration Method Based on Spectrally Reproduced Colors and its Application to XYZ-Type Digital Camera." Advanced Materials Research 222 (April 2011): 98–101. http://dx.doi.org/10.4028/www.scientific.net/amr.222.98.
Повний текст джерелаАнотація:
This paper presents the development of a color calibration method based on spectrally reproduced colors produced by multi-primary color narrow-band LED’s. The additive mixture of the primary colors can spectrally reproduce an object color. This approach has been used in our work to overcome the insufficient calibration results obtained by commonly used color targets such as the Macbeth Chart. The method has been tested using a developed prototype of digitally controlled light source calibrated to simulate object color under D65 Daylight standard illumination. The method allows for obtaining of the average color difference for the calibrated XYZ camera of ∆E=0.79 and shows significant improvement in comparison with calibration using standard Macbeth (∆E=1.47). Moreover, we explain the advantages of color calibration with usage of multi-primary light source with regard to the amount of the primary colors.
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Francioni, Simone, Stead, Sciarra, Mataloni, and Calamita. "A New Fast and Low-Cost Photogrammetry Method for the Engineering Characterization of Rock Slopes." Remote Sensing 11, no. 11 (May 28, 2019): 1267. http://dx.doi.org/10.3390/rs11111267.
Повний текст джерелаАнотація:
Digital photogrammetry (DP) represents one of the most used survey techniques in engineering geology. The availability of new high-resolution digital cameras and photogrammetry software has led to a step-change increase in the quality of engineering and structural geological data that can be collected. In particular, the introduction of the structure from motion methodology has led to a significant increase in the routine uses of photogrammetry in geological and engineering geological practice, making this method of survey easier and more attractive. Using structure from motion methods, the creation of photogrammetric 3D models is now easier and faster, however the use of ground control points to scale/geo-reference the models are still required. This often leads to the necessity of using total stations or Global Positioning System (GPS) for the acquisition of ground control points. Although the integrated use of digital photogrammetry and total station/GPS is now common practice, it is clear that this may not always be practical or economically convenient due to the increase in cost of the survey. To address these issues, this research proposes a new method of utilizing photogrammetry for the creation of georeferenced and scaled 3D models not requiring the use of total stations and GPS. The method is based on the use of an object of known geometry located on the outcrop during the survey. Targets located on such objects are used as ground control points and their coordinates are calculated using a simple geological compass and trigonometric formula or CAD 3D software. We present three different levels of survey using (i) a calibrated digital camera, (ii) a non-calibrated digital camera and (iii) two commercial smartphones. The data obtained using the proposed approach and the three levels of survey methods have been validated against a laser scanning (LS) point cloud. Through this validation we highlight the advantages and limitations of the proposed method, suggesting potential applications in engineering geology.
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Sužiedelytė-Visockienė, Jūratė. "TECHNIQUE FOR DEFINITION OF BREAK SIZE OF ROAD COVERING ON THE BRIDGE." TRANSPORT 22, no. 2 (June 30, 2007): 122–25. http://dx.doi.org/10.3846/16484142.2007.9638110.
Повний текст джерелаАнотація:
The article deals with the submitted photogrammetric method for image rectification to the planar coordinate system. The images are taken by metric digital camera Canon EOS 350D. The camera is calibrated with Technet(Pictran B, D/E) software using the special test‐field for calibration. Calibration parameters are determined to the images rectification process. The images in the planar coordinate system are transformed to 5 control points with the same software. The received results are visible in tables and figures. The transformed, planar images can be applied to research, designing and deformations estimate of engineering constructions.
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Lussem, U., J. Hollberg, J. Menne, J. Schellberg, and G. Bareth. "USING CALIBRATED RGB IMAGERY FROM LOW-COST UAVS FOR GRASSLAND MONITORING: CASE STUDY AT THE RENGEN GRASSLAND EXPERIMENT (RGE), GERMANY." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W6 (August 23, 2017): 229–33. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w6-229-2017.
Повний текст джерелаАнотація:
Monitoring the spectral response of intensively managed grassland throughout the growing season allows optimizing fertilizer inputs by monitoring plant growth. For example, site-specific fertilizer application as part of precision agriculture (PA) management requires information within short time. But, this requires field-based measurements with hyper- or multispectral sensors, which may not be feasible on a day to day farming practice. Exploiting the information of RGB images from consumer grade cameras mounted on unmanned aerial vehicles (UAV) can offer cost-efficient as well as near-real time analysis of grasslands with high temporal and spatial resolution. The potential of RGB imagery-based vegetation indices (VI) from consumer grade cameras mounted on UAVs has been explored recently in several. However, for multitemporal analyses it is desirable to calibrate the digital numbers (DN) of RGB-images to physical units. In this study, we explored the comparability of the RGBVI from a consumer grade camera mounted on a low-cost UAV to well established vegetation indices from hyperspectral field measurements for applications in grassland. The study was conducted in 2014 on the Rengen Grassland Experiment (RGE) in Germany. Image DN values were calibrated into reflectance by using the Empirical Line Method (Smith & Milton 1999). Depending on sampling date and VI the correlation between the UAV-based RGBVI and VIs such as the NDVI resulted in varying R2 values from no correlation to up to 0.9. These results indicate, that calibrated RGB-based VIs have the potential to support or substitute hyperspectral field measurements to facilitate management decisions on grasslands.
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Jia, Biao, Haibing He, Fuyu Ma, Ming Diao, Guiying Jiang, Zhong Zheng, Jin Cui, and Hua Fan. "Use of a Digital Camera to Monitor the Growth and Nitrogen Status of Cotton." Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/602647.
Повний текст джерелаАнотація:
The main objective of this study was to develop a nondestructive method for monitoring cotton growth and N status using a digital camera. Digital images were taken of the cotton canopies between emergence and full bloom. The green and red values were extracted from the digital images and then used to calculate canopy cover. The values of canopy cover were closely correlated with the normalized difference vegetation index and the ratio vegetation index and were measured using a GreenSeeker handheld sensor. Models were calibrated to describe the relationship between canopy cover and three growth properties of the cotton crop (i.e., aboveground total N content, LAI, and aboveground biomass). There were close, exponential relationships between canopy cover and three growth properties. And the relationships for estimating cotton aboveground total N content were most precise, the coefficients of determination (R2) value was 0.978, and the root mean square error (RMSE) value was 1.479 g m−2. Moreover, the models were validated in three fields of high-yield cotton. The result indicated that the best relationship between canopy cover and aboveground total N content had anR2value of 0.926 and an RMSE value of 1.631 g m−2. In conclusion, as a near-ground remote assessment tool, digital cameras have good potential for monitoring cotton growth and N status.
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Banić, Nikola, and Sven Lončarić. "Green Stability Assumption: Unsupervised Learning for Statistics-Based Illumination Estimation." Journal of Imaging 4, no. 11 (October 29, 2018): 127. http://dx.doi.org/10.3390/jimaging4110127.
Повний текст джерелаАнотація:
In the image processing pipeline of almost every digital camera, there is a part for removing the influence of illumination on the colors of the image scene. Tuning the parameter values of an illumination estimation method for maximal accuracy requires calibrated images with known ground-truth illumination, but creating them for a given sensor is time-consuming. In this paper, the green stability assumption is proposed that can be used to fine-tune the values of some common illumination estimation methods by using only non-calibrated images. The obtained accuracy is practically the same as when training on calibrated images, but the whole process is much faster since calibration is not required and thus time is saved. The results are presented and discussed. The source code website is provided in Section Experimental Results.
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Mueller, C., and K. Neumann. "LEICA DMC III CALIBRATION AND GEOMETRIC SENSOR ACCURACY." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3/W4 (March 17, 2016): 1–9. http://dx.doi.org/10.5194/isprsarchives-xl-3-w4-1-2016.
Повний текст джерелаАнотація:
As an evolution of the successful DMC II digital camera series, Leica Geosystems has introduced the Leica DMC III digital aerial camera using, for the first time in the industry, a large-format CMOS sensor as a panchromatic high-resolution camera head. This paper describes the Leica DMC III calibration and its quality assurance and quality control (QA/QC) procedures. It will explain how calibration was implemented within the production process for the Leica DMC III camera. Based on many years of experience with the DMC and DMC II camera series, it is know that the sensor flatness has a huge influence on the final achievable results. The Leica DMC III panchromatic CMOS sensor with its 100.3mm x 56.9mm size shows remaining errors in a range of 0.1 to 0.2μm for the root mean square and shows maximum values not higher that 1.0μm. The Leica DMC III is calibrated based on a 5cm Ground Sample Distance (GSD) grid pattern flight and evaluated with three different flying heights at 5cm, 8cm and 11cm GSD. The geometric QA/QC has been performed using the calibration field area, as well as using an independent test field. The geometric performance and accuracy is unique and gives ground accuracies far better than the flown GSD.
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Mueller, C., and K. Neumann. "LEICA DMC III CALIBRATION AND GEOMETRIC SENSOR ACCURACY." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3/W4 (March 17, 2016): 1–9. http://dx.doi.org/10.5194/isprs-archives-xl-3-w4-1-2016.
Повний текст джерелаАнотація:
As an evolution of the successful DMC II digital camera series, Leica Geosystems has introduced the Leica DMC III digital aerial camera using, for the first time in the industry, a large-format CMOS sensor as a panchromatic high-resolution camera head. This paper describes the Leica DMC III calibration and its quality assurance and quality control (QA/QC) procedures. It will explain how calibration was implemented within the production process for the Leica DMC III camera. Based on many years of experience with the DMC and DMC II camera series, it is know that the sensor flatness has a huge influence on the final achievable results. The Leica DMC III panchromatic CMOS sensor with its 100.3mm x 56.9mm size shows remaining errors in a range of 0.1 to 0.2μm for the root mean square and shows maximum values not higher that 1.0μm. The Leica DMC III is calibrated based on a 5cm Ground Sample Distance (GSD) grid pattern flight and evaluated with three different flying heights at 5cm, 8cm and 11cm GSD. The geometric QA/QC has been performed using the calibration field area, as well as using an independent test field. The geometric performance and accuracy is unique and gives ground accuracies far better than the flown GSD.
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Tommaselli, A. M. G., A. Berveglieri, N. N. Imai, G. H. Santos, E. A. S. Moriya, F. S. Y. Watanabe, and L. Salvador Neto. "GEOMETRIC PERFORMANCE OF A CAMERA WITH SINGLE SENSOR AND MULTIPLE HEADS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B1-2020 (August 6, 2020): 389–96. http://dx.doi.org/10.5194/isprs-archives-xliii-b1-2020-389-2020.
Повний текст джерелаАнотація:
Abstract. Remote sensing with lightweight optical sensors is becoming a powerful tool to solve many problems in agriculture. Achieving the level of spatial and spectral resolutions required for this type of detection at an acceptable cost-benefit ratio has motivated the development of new sensors which must be lightweight to be carried by mobile robots either aerial or terrestrial. One new type of multiple head cameras has been developed by Agrowing, an Israeli company developing technology for digital agriculture. The aim of this paper is to analyse the geometric features of an Agrowing dual head camera trough calibration experiments. The sensor was calibrated following two options, depending on the cropping technique used to produce the 4 spectral bands. Different calibration techniques were also used and very accurate results were achieved. Experiments with data collected with a UAV also confirmed the results achieved with close range calibration.
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Videc, Barbara, and Jurij Rakun. "Estimating the size of plants by using two parallel views." Agricultura 14, no. 1-2 (December 20, 2017): 1–7. http://dx.doi.org/10.1515/agricultura-2017-0012.
Повний текст джерелаАнотація:
AbstractThis paper presents a method of estimating the size of plants by using two parallel views of the scene, taken by a common digital camera. The approach relays on the principle of similar triangles with the following constraints: the resolution of the camera is known; the object is always in parallel to the camera sensor and the intermediate distance between the two concessive images is available. The approach was first calibrated and tested using one artificial object in a controlled environment. After that real examples were taken from agriculture, where we measured the distance and the size of a vine plant, apple and pear tree. By comparing the calculated values to measured values, we concluded that the average absolute error in distance was 0.11 m or around 3.7 %, and the absolute error in high was 0.09 m or 4.6 %.
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Hu, Xiang Chao, Bao Liang Zhu, Jian Wei Zhao, Xiao Fei Huang, and De Meng Yang. "A Novel Portable DCRP System for Tunnel-Wall Deformation Measurement Based on Non-Metric Digital Camera." Applied Mechanics and Materials 687-691 (November 2014): 998–1002. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.998.
Повний текст джерелаАнотація:
Compared to traditional manual-operation method for tunnel-wall deformation measurement, DCRP (Digital Close Range Photogrammetry) technique based on non-metric digital camera is a new emerging and more effective non-contact measurement method. In practical applications, the deformation parameter measurement jobs are throughout the entire process of the tunnel construction to ensure the safety of the project. There are urgent requirements for portability and miniaturization performances of the measurement system to reduce the interaction of measurement job and project construction. A configurable 3D control field equipment was presented, the control points of which could be freely configured according to the practical work conditions and do not need to be re-calibrated. A novel portable tunnel-wall deformation measurement system based on the non-metric digital camera and DLT algorithm was set up. Experimental results showed that the precision of the system for a large section tunnel-wall deformation measurement is better than 0.1‰. The system presented in the paper has the advantages of portability and miniaturization, as easy to implement fast and in-situ tunnel-wall deformation measurements.
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Manninen, Terhikki, Kati Anttila, Tuure Karjalainen, and Panu Lahtinen. "Automatic snow surface roughness estimation using digital photos." Journal of Glaciology 58, no. 211 (2012): 993–1007. http://dx.doi.org/10.3189/2012jog11j144.
Повний текст джерелаАнотація:
AbstractA surface roughness measurement system for snow is presented. It is based on a background board with scales on the edges and a digital camera. Analysis software is developed for automatic processing of images to produce calibrated profiles. The image analysis and calibration was fully automatic in >99% of the studied cases. In the others, the intensity adjustment or board detection needed manual intervention. Profile detection, control point picking and calibration always worked autonomously. The accuracy of the system depends on the photographing configuration, and is typically of the order of 0.1 mm vertically and 0.04 mm horizontally. The method tolerates relatively well cases of snowfall, traces of wiping the black background dry, uneven shading, reflected sunlight, reflected flash light, litter on the snow surface and a tilted plate. The repeatability of the system is at least 1%.
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Amini, A. Sh, M. Varshosaz, and M. Saadatseresht. "APPLYING CCD CAMERAS IN STEREO PANORAMA SYSTEMS FOR 3D ENVIRONMENT RECONSTRUCTION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XXXIX-B5 (July 27, 2012): 257–60. http://dx.doi.org/10.5194/isprsarchives-xxxix-b5-257-2012.
Повний текст джерелаАнотація:
Proper recontruction of 3D environments is nowadays needed by many organizations and applications. In addition to conventional methods the use of stereo panoramas is an appropriate technique to use due to simplicity, low cost and the ability to view an environment the way it is in reality. This paper investigates the ability of applying stereo CCD cameras for 3D reconstruction and presentation of the environment and geometric measuring among that. For this purpose, a rotating stereo panorama was established using two CCDs with a base-length of 350 mm and a DVR (digital video recorder) box. The stereo system was first calibrated using a 3D test-field and used to perform accurate measurements. The results of investigating the system in a real environment showed that although this kind of cameras produce noisy images and they do not have appropriate geometric stability, but they can be easily synchronized, well controlled and reasonable accuracy (about 40 mm in objects at 12 meters distance from the camera) can be achieved.
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Káňa, David, and Vlastimil Hanzl. "Application of Computer Vision Methods and Algorithms in Documentation of Cultural Heritage." Geoinformatics FCE CTU 9 (December 22, 2012): 27–38. http://dx.doi.org/10.14311/gi.9.3.
Повний текст джерелаАнотація:
The main task of this paper is to describe methods and algorithms used in computer vision for fully automatic reconstruction of exterior orientation in ordered and unordered sets of images captured by digital calibrated cameras without prior informations about camera positions or scene structure. Attention will be paid to the SIFT interest operator for finding key points clearly describing the image areas with respect to scale and rotation, so that these areas could be compared to the regions in other images. There will also be discussed methods of matching key points, calculation of the relative orientation and strategy of linking sub-models to estimate the parameters entering complex bundle adjustment. The paper also compares the results achieved with above system with the results obtained by standard photogrammetric methods in processing of project documentation for reconstruction of the Žinkovy castle.
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Oniga, Valeria-Ersilia, Norbert Pfeifer, and Ana-Maria Loghin. "3D Calibration Test-Field for Digital Cameras Mounted on Unmanned Aerial Systems (UAS)." Remote Sensing 10, no. 12 (December 12, 2018): 2017. http://dx.doi.org/10.3390/rs10122017.
Повний текст джерелаАнотація:
Due to the large number of technological developments in recent years, UAS systems are now used for monitoring purposes and in projects with high precision demand, such as 3D model-based creation of dams, reservoirs, historical monuments etc. These unmanned systems are usually equipped with an automatic pilot device and a digital camera (photo/video, multispectral, Near Infrared etc.), of which the lens has distortions; but this can be determined in a calibration process. Currently, a method of “self-calibration” is used for the calibration of the digital cameras mounted on UASs, but, by using the method of calibration based on a 3D calibration object, the accuracy is improved in comparison with other methods. Thus, this paper has the objective of establishing a 3D calibration field for the digital cameras mounted on UASs in terms of accuracy and robustness, being the largest reported publication to date. In order to test the proposed calibration field, a digital camera mounted on a low-cost UAS was calibrated at three different heights: 23 m, 28 m, and 35 m, using two configurations for image acquisition. Then, a comparison was made between the residuals obtained for a number of 100 Check Points (CPs) using self-calibration and test-field calibration, while the number of Ground Control Points (GCPs) variedand the heights were interchanged. Additionally, the parameters where tested on an oblique flight done 2 years before calibration, in manual mode at a medium altitude of 28 m height. For all tests done in the case of the double grid nadiral flight, the parameters calculated with the proposed 3D field improved the results by more than 50% when using the optimum and a large number of GCPs, and in all analyzed cases with 75% to 95% when using a minimum of 3 GCP. In this context, it is necessary to conduct accurate calibration in order to increase the accuracy of the UAS projects, and also to reduce field measurements.
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Garcia, M. V. Y., and H. C. Oliveira. "THE INFLUENCE OF GROUND CONTROL POINTS CONFIGURATION AND CAMERA CALIBRATION FOR DTM AND ORTHOMOSAIC GENERATION USING IMAGERY OBTAINED FROM A LOW-COST UAV." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences V-1-2020 (August 3, 2020): 239–44. http://dx.doi.org/10.5194/isprs-annals-v-1-2020-239-2020.
Повний текст джерелаАнотація:
Abstract. Technological improvement of Unmanned Aerial Vehicles (UAVs) and computer vision algorithms, such as Structured-from-Motion (SfM) and Multi-view Stereo (MVS) have provided the possibility for high-resolution mapping and high-density point cloud generation using low-cost equipment and sensors. Orthomosaics and Digital Terrain Model (DTM) are the main digital products considering mapping purposes. Their quality is directly related to the sensors boarded on the UAV and data processing. Ground Control Points (GCPs) are used in the process of indirect georeferencing and also to model the lens distortions. The number of GCPs used in this process affects the positional accuracy of the final products. This study aims to determine the optimum number of GCPs to achieve high accuracy orthomosaics and DTM. To obtain this optimum number, an area of 3.85 ha was mapped with a low-cost UAV DJI Phantom 4 Advanced at 31 m flying height, lateral and longitudinal overlap of 90% and 80%, respectively, and using 22 checkpoints for quality assessment. For the experiments, different configuration were used both for the number of GCPs and for the use of self-calibration process or pre-calibrated camera IOP (Interior Orientation Parameters). The results show that for the flight configuration used in this work and for the mentioned UAV, a total of 5 GCPs, with pre-calibrated camera IOP, yields an accuracy of 0.023 m for X, 0.031 m for Y and 0.033 m for Z.
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Zheng, Li Gang, Ming Gao Yu, Shui Jun Yu, and Chang Lu. "Measurement of Flame Height by Image Processing Method." Advanced Materials Research 301-303 (July 2011): 983–88. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.983.
Повний текст джерелаАнотація:
In order to measure the flame height (Lf), the image processing method was employed. The jet flame image was captured by the common-used digital camera. The resolution (C, with the unit of mm/pixel) of the pixel of the digital camera was calibrated by metric scale. The jet flame image was then successively processed by ROI (region of interest) processing, gray processing, binarization and edge detection. Through the image processing, the pixels where the flame root and the flame tip were located was detected. The flame region expressed in pixels can be easily obtained by the difference between the flame root (X1) and the flame tip(X2). The flame height (Lf) was calculated by multiplying the difference in pixels (Lp= X2-X1) with the resolution of pixel (in millimetres per pixel). Using the proposed method, the flame heights of the pulverized coal jet flame at the high temperature air combustion condition were measured. The effect of experimental parameters on the flame heights of the coal jet flame was discussed.
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Wierzbicki, Damian. "Multi-Camera Imaging System for UAV Photogrammetry." Sensors 18, no. 8 (July 26, 2018): 2433. http://dx.doi.org/10.3390/s18082433.
Повний текст джерелаАнотація:
In the last few years, it has been possible to observe a considerable increase in the use of unmanned aerial vehicles (UAV) equipped with compact digital cameras for environment mapping. The next stage in the development of photogrammetry from low altitudes was the development of the imagery data from UAV oblique images. Imagery data was obtained from side-facing directions. As in professional photogrammetric systems, it is possible to record footprints of tree crowns and other forms of the natural environment. The use of a multi-camera system will significantly reduce one of the main UAV photogrammetry limitations (especially in the case of multirotor UAV) which is a reduction of the ground coverage area, while increasing the number of images, increasing the number of flight lines, and reducing the surface imaged during one flight. The approach proposed in this paper is based on using several head cameras to enhance the imaging geometry during one flight of UAV for mapping. As part of the research work, a multi-camera system consisting of several cameras was designed to increase the total Field of View (FOV). Thanks to this, it will be possible to increase the ground coverage area and to acquire image data effectively. The acquired images will be mosaicked in order to limit the total number of images for the mapped area. As part of the research, a set of cameras was calibrated to determine the interior orientation parameters (IOPs). Next, the method of image alignment using the feature image matching algorithms was presented. In the proposed approach, the images are combined in such a way that the final image has a joint centre of projections of component images. The experimental results showed that the proposed solution was reliable and accurate for the mapping purpose. The paper also presents the effectiveness of existing transformation models for images with a large coverage subjected to initial geometric correction due to the influence of distortion.
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Irvine-Fynn, Tristram D. L., Enoc Sanz-Ablanedo, Nick Rutter, Mark W. Smith, and Jim H. Chandler. "Measuring glacier surface roughness using plot-scale, close-range digital photogrammetry." Journal of Glaciology 60, no. 223 (2014): 957–69. http://dx.doi.org/10.3189/2014jog14j032.
Повний текст джерелаАнотація:
AbstractGlacier roughness at sub-metre scales is an important control on the ice surface energy balance and has implications for scattering energy measured by remote-sensing instruments. Ice surface roughness is dynamic as a consequence of spatial and temporal variation in ablation. To date, studies relying on singular and/or spatially discrete two-dimensional profiles to describe ice surface roughness have failed to resolve common patterns or causes of variation in glacier surface morphology. Here we demonstrate the potential of close-range digital photogrammetry as a rapid and cost-effective method to retrieve three-dimensional data detailing plot-scale supraglacial topography. The photogrammetric approach here employed a calibrated, consumer-grade 5 Mpix digital camera repeatedly imaging a plot-scale (≤25 m2) ice surface area on Midtre Lovénbreen, Svalbard. From stereo-pair images, digital surface models (DSMs) with sub-centimetre horizontal resolution and 3 mm vertical precision were achieved at plot scales ≤4 m2. Extraction of roughness metrics including estimates of aerodynamic roughness length (z0) was readily achievable, and temporal variations in the glacier surface topography were captured. Close-range photogrammetry, with appropriate camera calibration and image acquisition geometry, is shown to be a robust method to record sub-centimetre variations in ablating ice topography. While the DSM plot area may be limited through use of stereo-pair images and issues of obliquity, emerging photogrammetric packages are likely to overcome such limitations.
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Tekwani, Hema, and Krishna Raj. "Correlation-Based Template Tracking Of Moving Object." International journal of electrical and computer engineering systems 13, no. 3 (April 19, 2022): 175–82. http://dx.doi.org/10.32985/ijeces.13.3.2.
Повний текст джерелаАнотація:
This paper presents the correlation-based motion estimation technique for the 3D displacement of objects. Two high-speed cameras are configured as a stereovision system and synchronized in real-time. Finger and hand motions are captured in form of digital images at 1500 fps and 2000 fps respectively. A complete motion acquisition system is calibrated to determine the intrinsic and extrinsic parameters which were later used in the correlation algorithm. The grayscale image frames acquired from the cameras are correlated using square templates of 10x10 pixels created from the reference image. The finger and hand motion are discussed with varying camera speed as a measure of brightness inconsistency. The observations in the correlation coefficient indicate that the proposed algorithm is efficient up to 20 and 50 templates for the finger and hand motion cases respectively. The correlation coefficient for finger motion was increased to 0.987 and 0.972 for the left and right cameras, respectively, while the correlation coefficient for hand motion was 0.924 and 0.898. The proposed algorithm is developed in MATLAB and validated by tracing the sinusoidal motion of a solid rectangular element from the image correlation technique and an accelerometer sensor mounted over the block.
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Majid, Z., M. F. M. Ariff, K. M. Idris, A. R. Yusoff, K. M. Idris, A. Aspuri, M. A. Abbas, K. Zainuddin, A. R. A. Ghani, and A. A. Bin Saeman. "THREE-DIMENSIONAL MAPPING OF AN ANCIENT CAVE PAINTINGS USING CLOSE-RANGE PHOTOGRAMMETRY AND TERRESTRIAL LASER SCANNING TECHNOLOGIES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W3 (February 23, 2017): 453–57. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w3-453-2017.
Повний текст джерелаАнотація:
The paper describes the used of close-range photogrammetry and terrestrial laser scanning technologies as an innovative technology for acquiring the three-dimensional data of an ancient cave paintings. The close-range photogrammetry technology used in the research was divided in two categories which are the UAV-based close-range photogrammetry and the terrestrialbased close-range photogrammetry. The UAV-based technology involved with the used of calibrated Phantom 4 System while the terrestrial-based technology involved with the calibrated Sony F828 digital camera and pPhotoModeler software. Both stereo and convergent image acquisition techniques were used to acquire the images of the paintings. The ancient cave paintings were also recorded using terrestrial laser scanning technology. In the research, the FARO Focus 3D terrestrial laser scanner was used to capture the three-dimensional point clouds and images of the paintings. The finding shows that both close-range photogrammetry and laser scanning technologies provide excellent solutions to map and to record the ancient paintings. As compared to the conventional method, both close-range photogrammetry and terrestrial laser scanning technology provide a noncontact solution for data acquisition and the data was recorded in digital format for better protection and security.
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Rehak, M., and J. Skaloud. "FIXED-WING MICRO AERIAL VEHICLE FOR ACCURATE CORRIDOR MAPPING." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-1/W1 (August 27, 2015): 23–31. http://dx.doi.org/10.5194/isprsannals-ii-1-w1-23-2015.
Повний текст джерелаАнотація:
In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.
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Sun, Mao Heng, Yi Xin Zhao, Wei Jiang, and Tian Tian Feng. "A Scheme for Excavation Displacement Monitoring Based on Image Processing." Applied Mechanics and Materials 226-228 (November 2012): 1923–26. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1923.
Повний текст джерелаАнотація:
Geotechnical monitoring is integral part of each excavation project and usually done with manual manner. This study proposes a new monitoring method, which combines with image processing and wireless communication to break traditional one. The scheme uses image sensors to capture the images of the cooperative boards. The camera system is calibrated by Zhang Zhengyou calibration method beforehand. Digital signal processors in the image acquisition module generate the undistorted version of the images by the calibration results and utilize Harris corner detection algorithm to extract grid corners’ coordinates. Then these coordinates are sent to the data processing center through wireless sensor network. In the data processing center, the computer calculates the real displacement of the target by the extrinsic parameters of the camera. The experiment in this paper proves that the systematic accuracy satisfies the national standard. The system realizes the automatic real-time monitoring to excavation works.
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Holman, Fenner H., Andrew B. Riche, March Castle, Martin J. Wooster, and Malcolm J. Hawkesford. "Radiometric Calibration of ‘Commercial off the Shelf’ Cameras for UAV-Based High-Resolution Temporal Crop Phenotyping of Reflectance and NDVI." Remote Sensing 11, no. 14 (July 11, 2019): 1657. http://dx.doi.org/10.3390/rs11141657.
Повний текст джерелаАнотація:
Vegetation indices, such as the Normalised Difference Vegetation Index (NDVI), are common metrics used for measuring traits of interest in crop phenotyping. However, traditional measurements of these indices are often influenced by multiple confounding factors such as canopy cover and reflectance of underlying soil, visible in canopy gaps. Digital cameras mounted to Unmanned Aerial Vehicles offer the spatial resolution to investigate these confounding factors, however incomplete methods for radiometric calibration into reflectance units limits how the data can be applied to phenotyping. In this study, we assess the applicability of very high spatial resolution (1 cm) UAV-based imagery taken with commercial off the shelf (COTS) digital cameras for both deriving calibrated reflectance imagery, and isolating vegetation canopy reflectance from that of the underlying soil. We present new methods for successfully normalising COTS camera imagery for exposure and solar irradiance effects, generating multispectral (RGB-NIR) orthomosaics of our target field-based wheat crop trial. Validation against measurements from a ground spectrometer showed good results for reflectance (R2 ≥ 0.6) and NDVI (R2 ≥ 0.88). Application of imagery collected through the growing season and masked using the Excess Green Red index was used to assess the impact of canopy cover on NDVI measurements. Results showed the impact of canopy cover artificially reducing plot NDVI values in the early season, where canopy development is low.
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Girman, Peter, Jan Kříž, Jozef Friedmanský, and FrantišEk Saudek. "Digital Imaging as a Possible Approach in Evaluation of Islet Yield." Cell Transplantation 12, no. 2 (March 2003): 129–33. http://dx.doi.org/10.3727/000000003108746713.
Повний текст джерелаАнотація:
Digital image analysis (DIA) is a new method in assessment of islet amount, which is expected to provide reliable and consistent results. We compared this method with conventional counting of small numbers of rat islets. Islets were isolated from 8 pancreases and counted in 24 samples in duplicate, first routinely by sizing according to estimated diameters under a calibrated reticule and then by processing of islets pictures taken by camera. As presumed, no significant difference was found in absolute numbers of islets per sample between DIA and conventional assessment. Volumes of islets per sample measured by DIA were on average more than 10% higher than amounts evaluated conventionally, which was statistically significant. DIA has been shown to be an important method to remove operator bias and provide consistent results. Evaluation of only two dimensions of three-dimensional objects still represents a certain limitation of this technique. With lowering of computer prices the system could become easily available for islet laboratories.
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Shibayama, Michio, Toshihiro Sakamoto, Eiji Takada, Akihiro Inoue, Kazuhiro Morita, Wataru Takahashi, and Akihiko Kimura. "Estimating Paddy Rice Leaf Area Index with Fixed Point Continuous Observation of Near Infrared Reflectance Using a Calibrated Digital Camera." Plant Production Science 14, no. 1 (January 2011): 30–46. http://dx.doi.org/10.1626/pps.14.30.
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Kayı, Abdullah, Bülent Bayram, and Dursun Zafer Şeker. "The Analysis on the Annual Change of Digital Aerial Camera's IMUs Boresight Misalignment." Photogrammetric Engineering & Remote Sensing 87, no. 11 (November 1, 2021): 801–6. http://dx.doi.org/10.14358/pers.21-00002r2.
Повний текст джерелаАнотація:
The system calibration determines the position and orientation between the sensor and the navigation systems, such as boresight misalignment. Although there is much research about boresight calibration, there are not sufficient studies on the frequency of the calibration performance. The short-term stability of boresight misalignment was investigated in previous studies, but long-term stability research could not be done. It is important to emphasize that long-term stability is still open to questions. In this study, an Ultracam Eagle digital aerial camera's data from 2012 to 2016 were analyzed and the question of how often calibration should be performed was investigated. Boresight misalignment does not remain constant on a yearly basis and should be calibrated every year before the flight season. It was observed that the boresight misalignment changed dramatically when the inertial measurement unit or camera was removed from the aircraft and sent to the manufacturer for factory calibration.
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Ehrlich, A., E. Bierwirth, M. Wendisch, A. Herber, and J. F. Gayet. "Airborne hyperspectral observations of surface and cloud directional reflectivity using a commercial digital camera." Atmospheric Chemistry and Physics 12, no. 7 (April 11, 2012): 3493–510. http://dx.doi.org/10.5194/acp-12-3493-2012.
Повний текст джерелаАнотація:
Abstract. Spectral radiance measurements by a digital single-lens reflex camera were used to derive the directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measurements with the Spectral Modular Airborne Radiation measurement sysTem (SMART-Albedometer) showed an agreement within the uncertainties of both instruments (6% for both). The directional reflectivity in terms of the hemispherical directional reflectance factor (HDRF) was obtained for sea ice, ice-free ocean and clouds. The sea ice, with an albedo of ρ = 0.96 (at 530 nm wavelength), showed an almost isotropic HDRF, while sun glint was observed for the ocean HDRF (ρ = 0.12). For the cloud observations with ρ = 0.62, the cloudbow – a backscatter feature typically for scattering by liquid water droplets – was covered by the camera. For measurements above heterogeneous stratocumulus clouds, the required number of images to obtain a mean HDRF that clearly exhibits the cloudbow has been estimated at about 50 images (10 min flight time). A representation of the HDRF as a function of the scattering angle only reduces the image number to about 10 (2 min flight time). The measured cloud and ocean HDRF have been compared to radiative transfer simulations. The ocean HDRF simulated with the observed surface wind speed of 9 m s−1 agreed best with the measurements. For the cloud HDRF, the best agreement was obtained by a broad and weak cloudbow simulated with a cloud droplet effective radius of Reff = 4 μm. This value agrees with the particle sizes derived from in situ measurements and retrieved from the spectral radiance of the SMART-Albedometer.
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Soler, M. E., W. Kornus, A. Magariños, and M. Pla. "ANALYZING RCD30 OBLIQUE PERFORMANCE IN A PRODUCTION ENVIRONMENT." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 99–105. http://dx.doi.org/10.5194/isprs-archives-xli-b3-99-2016.
Повний текст джерелаАнотація:
In 2014 the Institut Cartogràfic i Geològic de Catalunya (ICGC) decided to incorporate digital oblique imagery in its portfolio in response to the growing demand for this product. The reason can be attributed to its useful applications in a wide variety of fields and, most recently, to an increasing interest in 3d modeling. The selection phase for a digital oblique camera led to the purchase of the Leica RCD30 Oblique system, an 80MPixel multispectral medium-format camera which consists of one Nadir camera and four oblique viewing cameras acquiring images at an off-Nadir angle of 35º. The system also has a multi-directional motion compensation on-board system to deliver the highest image quality. <br><br> The emergence of airborne oblique cameras has run in parallel to the inclusion of computer vision algorithms into the traditional photogrammetric workflows. Such algorithms rely on having multiple views of the same area of interest and take advantage of the image redundancy for automatic feature extraction. The multiview capability is highly fostered by the use of oblique systems which capture simultaneously different points of view for each camera shot. Different companies and NMAs have started pilot projects to assess the capabilities of the 3D mesh that can be obtained using correlation techniques. Beyond a software prototyping phase, and taking into account the currently immature state of several components of the oblique imagery workflow, the ICGC has focused on deploying a real production environment with special interest on matching the performance and quality of the existing production lines based on classical Nadir images. <br><br> This paper introduces different test scenarios and layouts to analyze the impact of different variables on the geometric and radiometric performance. Different variables such as flight altitude, side and forward overlap and ground control point measurements and location have been considered for the evaluation of aerial triangulation and stereo plotting. Furthermore, two different flight configurations have been designed to measure the quality of the absolute radiometric calibration and the resolving power of the system. <br><br> To quantify the effective resolution power of RCD30 Oblique images, a tool based on the computation of the Line Spread Function has been developed. The tool processes a region of interest that contains a single contour in order to extract a numerical measure of edge smoothness for a same flight session. The ICGC is highly devoted to derive information from satellite and airborne multispectral remote sensing imagery. A seamless Normalized Difference Vegetation Index (NDVI) retrieved from Digital Metric Camera (DMC) reflectance imagery is one of the products of ICGC’s portfolio. As an evolution of this well-defined product, this paper presents an evaluation of the absolute radiometric calibration of the RCD30 Oblique sensor. To assess the quality of the measure, the ICGC has developed a procedure based on simultaneous acquisition of RCD30 Oblique imagery and radiometric calibrated AISA (Airborne Hyperspectral Imaging System) imagery.