Determination of the Interior Orientation Parameters of a Non-metric Digital Camera for Terrestrial Photogrammetric Applications (original) (raw)
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Small and medium format digital cameras are widely used in Photogrammetric applications due to their accessibility, availability and quick image acquisition and processing. In addition, the resolution of these cameras has significantly increased while their prices decreased. Generally, a small-format digital camera does not have a pre-definition of the internal geometric characteristics, commonly known as the interior orientation parameters (IOPs), which are computed by a bundle adjustment with a self-calibration procedure that uses a set of images, geometrically acquired over the calibration test field. However, to extract precise and reliable 3D metric information from images, an important condition should be considered: are the interior orientation parameters accurate enough for photogrammetric applications? Usually, the camera calibration procedure is performed using a target or a linear test field, regardless of the photogrammetric project that will be performed later. For phot...
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Nowadays, unmanned aircrafts are more frequently used for measurement purposes. Size of aircrafts is often proportional to its price and load. Aircraft load of 2-3 kg, as required to lift DSLR camera, lens and gimbal (camera stabilizer) in the air, are higher-priced (>50,000 kn). Those kinds of aircrafts have their limits within the law, but also practical limitations because of its size. With the development of autonomous small size cameras such as action cameras appeared the ability to use cheaper, smaller and unmanned aircrafts with lower load in photogrammetric purposes. Of course, to use such a camera in measuring purposes first it is necessary to carry out adequate calibration method and define the elements of internal orientation of the camera. It is important to emphasize that the geometric calibration, or the elimination of geometric errors in the mapping is the key precondition to create idealized images i.e. images of actual optical mapping. This paper researches the quality of content mapped on images with the purpose of investigating the possibility of using action cameras in measuring purposes. The study is based on objective indicators such as global statistical image quality parameters, Modulation Transfer Function and visual analysis of test field images. For the purpose of the paper a modified test field based on the ISO 12233 standard was developed and for the first time used.
In the last years, small and medium format digital cameras have become a potential tool for photogrammetric applications due to its convenience, availability and quick image acquisition and processing. In addition, the resolution of these cameras has significantly increased while their price decreased. However, to extract accurate and reliable 3D metric information from images, an important condition should be considered: Are the interior and exterior orientation parameters accurate enough for photogrammetric applications? Generally, the camera calibration procedure is performed using a target or a linear test field, regardless of the photogrammetric project that will be later performed. For photogrammetric applications, the camera should be stable and the interior orientation parameters not vary with time. In addition, the exterior orientation parameters of the images should be accurately determined. The exterior orientation parameters can be determined by indirect or direct geo-re...
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Quantitative measures for the evaluation of camera stability
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Increasing resolution and reducing costs of off-the-shelf digital cameras are giving rise to their utilization in traditional and new photogrammetric applications, and allowing amateur users to generate high-quality photogrammetric products. For most, if not all photogrammetric applications, the internal metric characteristics of such cameras need to be determined and analyzed. This is achieved by going through a camera calibration and stability analysis process using a specific test field configuration. In a traditional test field, precisely surveyed ground control points (GCPs) are used as control information. The proposed test field in this research involves the utilization of linear features. Two quantitative methods for testing camera stability are introduced, where the degree of similarity between reconstructed bundles from two sets of Interior Orientation Parameters (IOP) is evaluated. In addition, an illustration of the test field created for the experiments as well as a few technical details on each camera used in the calibrations are presented. Through experimentation, the stability of the estimated IOP of each camera over a period of eight months is quantified and analyzed.