Calibrating Photogrammetric Airborne Camera Systems With Diffractive Optical Elements

Abstract

<p><strong>Abstract.</strong> This paper presents a laboratory approach for geometric calibration of airborne camera systems. The setup uses an incoming laser beam, which is split by Diffractive Optical Elements (DOE) into a number of beams with precisely-known propagation directions. Each point of the diffraction pattern represents a point at infinity and is invariant against translation. A single image is sufficient to allow a complete camera calibration in accordance with classical camera calibration methods using the pinhole camera model and a distortion model. The presented method is time saving, since complex bundle adjustment procedures with several images are not necessary. It is well suited for the use with frame camera systems, but it works in principle also for pushbroom scanners. In order to prove the reliability, a conventional test field calibration is compared against the presented approach, showing that all estimated camera parameters are just insignificantly different. Furthermore a test flight over the Zeche Zollern reference target has been conducted. The aerotriangulation results shows that calibrating an airborne camera system with DOE is a feasible solution.</p>

High-Precision Object Delineation With Uav – Demonstrated on a Track System

“…The imaging model, which contains the calibration parameters of the camera, including the optical distortion, is iteratively optimized on the basis of an image. Dahlke et al (2019) show that this method leads to similar good results as a 3D test field calibration. A disadvantage of this approach, however, is that the distortion parameters and the focal length cannot be decorrelated since only one image is used.…”

“…The camera was calibrated at the Institute for Optical Sensor Systems, DLR, Berlin before the first flight. A method using optical diffraction (DOE, diffractive optical elements) was used, see (Bauer et al, 2008) and (Dahlke et al, 2019). In this calibration, a geometrically highly precisely defined pattern created by a laser and a diffraction unit is recorded by the camera behind a collimator.…”

Implementation and Validation of a High Accuracy UAV-Photogrammetry Based Rail Track Inspection System

“…6 micrometers, i.e., 1.5 pixels. As described in [1], the camera was pre-calibrated in the lab of DLR (Institute of Optical Sensor Systems) applying the diffractive optical elements (DOE) method [8]. The results of [1] suggest that the final results of the bundle block adjustment do not differ significantly between different camera calibration scenarios.…”

“…The tool chain deriving 3D models from aerial imagery benefits greatly from better image quality especially from better spatial resolution [8]. It is therefore advantageous to have knowledge of the spatial resolution of a specific sensor-lens combination in order to quantify later uncertainties (e.g., of bundle block adjustment or dense image matching).…”

Electrically Tuneable Optical Diffraction Gratings Based on a Polymer Scaffold Filled with a Nematic Liquid Crystal

“…They are standard in use as diffusers [ 7 ], beam splitters [ 8 ], beam samplers [ 9 ], beam shapers [ 10 ], axicons [ 11 ], vortex phase plates [ 12 ], etc. Lately, they have also found application in products such as 3D displays [ 13 ], consumer electronics [ 14 ], VR/AR/MR displays [ 15 ], automotive vehicles [ 16 ], and in fields such as robotics [ 17 ] or medically-required and elective surgery [ 18 , 19 ].…”