scholarly journals AUTOMATIC CAMERA SYSTEM CALIBRATION WITH A CHESSBOARD ENABLING FULL IMAGE COVERAGE

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 1715-1722
Author(s):  
J. Wohlfeil ◽  
D. Grießbach ◽  
I. Ernst ◽  
D. Baumbach ◽  
D. Dahlke
Keyword(s):  
Imaging System ◽  
Model Parameters ◽  
Camera Model ◽  
Camera System ◽  
Stereo Camera ◽  
Robust Detection ◽  
Rigid Frame ◽  
Fully Automatic ◽  
Consistent Error ◽  
Full Covariance Matrix

<p><strong>Abstract.</strong> Geometric camera calibration is a mandatory prerequisite for many applications in computer vision and photogrammetry. Especially when requiring an accurate camera model the effort for calibration can increase dramatically. For the calibration of the stereo-camera used for optical navigation a new chessboard based approach is presented. It is derived from different parts of existing approaches which, taken separately, are not able to meet the requirements. Moreover, the approach adds one novel main feature: It is able to detect all visible chessboard fields with the help of one or more fiducial markers simply sticked on a chessboard (AprilTags). This allows a robust detection of one or more chessboards in a scene, even from extreme perspectives. Except for the acquisition of the calibration images the presented approach enables a fully automatic calibration. Together with the parameters of the interior and relative orientation the full covariance matrix of all model parameters is calculated and provided, allowing a consistent error propagation in the whole processing chain of the imaging system. Even though the main use case for the approach is a stereo camera system it can be used for a multi-camera system with any number of cameras mounted on a rigid frame.</p>

Robust detection of moving target's height and trajectory using pan/tilt-embedded stereo camera system

2004 ◽  
Author(s):  
Jung-Hwan Ko ◽  
Jun-Ho Lee ◽  
Do-Hoon Kim ◽  
Jae-Hun Jang ◽  
Kwang-Jin Lee ◽  
...  
Keyword(s):  
Camera System ◽  
Stereo Camera ◽  
Robust Detection

scholarly journals EVALUATION OF STEREO ALGORITHMS FOR OBSTACLE DETECTION WITH FISHEYE LENSES

2015 ◽  
Vol II-1/W1 ◽  
pp. 33-40 ◽  
Author(s):  
N. Krombach ◽  
D. Droeschel ◽  
S. Behnke
Keyword(s):  
Autonomous Navigation ◽  
3D Structure ◽  
Urban Environments ◽  
Obstacle Detection ◽  
Field Of View ◽  
Model Parameters ◽  
Camera Model ◽  
Robust Detection ◽  
Depth Reconstruction ◽  
Fisheye Lenses

For autonomous navigation of micro aerial vehicles (MAVs), a robust detection of obstacles with onboard sensors is necessary in order to avoid collisions. Cameras have the potential to perceive the surroundings of MAVs for the reconstruction of their 3D structure. We equipped our MAV with two fisheye stereo camera pairs to achieve an omnidirectional field-of-view. Most stereo algorithms are designed for the standard pinhole camera model, though. Hence, the distortion effects of the fisheye lenses must be properly modeled and model parameters must be identified by suitable calibration procedures. In this work, we evaluate the use of real-time stereo algorithms for depth reconstruction from fisheye cameras together with different methods for calibration. In our experiments, we focus on obstacles occurring in urban environments that are hard to detect due to their low diameter or homogeneous texture.

Development of an Advanced Stereo Camera System

2007 ◽  
Author(s):  
Satoshi Katahira ◽  
Eiji Shibata ◽  
Tatsuhiko Monji
Keyword(s):  
Camera System ◽  
Stereo Camera

An Experimental Analysis of the Effects of Different Hardware Setups on Stereo Camera Systems

2021 ◽  
Vol 15 (03) ◽  
pp. 337-357
Author(s):  
Alexander Julian Golkowski ◽  
Marcus Handte ◽  
Peter Roch ◽  
Pedro J. Marrón
Keyword(s):  
Experimental Analysis ◽  
Autonomous Navigation ◽  
Indoor Environments ◽  
Camera System ◽  
Stereo Camera ◽  
Camera Systems ◽  
Sensing Technology ◽  
Stereo Cameras ◽  
The Impact ◽  
General Guidance

For many application areas such as autonomous navigation, the ability to accurately perceive the environment is essential. For this purpose, a wide variety of well-researched sensor systems are available that can be used to detect obstacles or navigation targets. Stereo cameras have emerged as a very versatile sensing technology in this regard due to their low hardware cost and high fidelity. Consequently, much work has been done to integrate them into mobile robots. However, the existing literature focuses on presenting the concepts and algorithms used to implement the desired robot functions on top of a given camera setup. As a result, the rationale and impact of choosing this camera setup are usually neither discussed nor described. Thus, when designing the stereo camera system for a mobile robot, there is not much general guidance beyond isolated setups that worked for a specific robot. To close the gap, this paper studies the impact of the physical setup of a stereo camera system in indoor environments. To do this, we present the results of an experimental analysis in which we use a given software setup to estimate the distance to an object while systematically changing the camera setup. Thereby, we vary the three main parameters of the physical camera setup, namely the angle and distance between the cameras as well as the field of view and a rather soft parameter, the resolution. Based on the results, we derive several guidelines on how to choose the parameters for an application.

scholarly journals IMAGE NETWORK GENERATION OF UNCALIBRATED UAV IMAGES WITH LOW-COST GPS DATA

2016 ◽  
Vol XLI-B3 ◽  
pp. 31-37 ◽  
Author(s):  
Shan Huang ◽  
Zuxun Zhang ◽  
Jianan He ◽  
Tao Ke
Keyword(s):  
Coordinate System ◽  
Low Cost ◽  
Reference Image ◽  
Model Parameters ◽  
Camera Model ◽  
Orientation Data ◽  
Network Generation ◽  
Free Network ◽  
Uav Images ◽  
Image Network

The use of unmanned air vehicle (UAV) images acquired by a non-metric digital camera to establish an image network is difficult in cases without accurate camera model parameters. Although an image network can be generated by continuously calculating camera model parameters during data processing as an incremental structure from motion (SfM) methods, the process is time consuming. In this study, low-cost global position system (GPS) information is employed in image network generation to decrease computational expenses. Each image is considered as reference, and its neighbor images are determined based on GPS coordinates during processing. The reference image and its neighbor images constitute an image group, which is used to generate a free network through image matching and relative orientation. Data are then transformed from the free network coordinate system of each group into the GPS coordinate system by using the GPS coordinates of each image. After the exterior elements of each image are determined in the GPS coordinate system, the initial image network is established. Finally, self-calibration bundle adjustment constrained by GPS coordinates is conducted to refine the image network. The proposed method is validated on three fields. Results confirm that the method can achieve good image network when accurate camera model parameters are unavailable.

3D-objecttracking with a mixed omnidirectional stereo camera system

Mechatronics ◽  
2011 ◽  
Vol 21 (2) ◽  
pp. 390-398 ◽  
Author(s):  
Martin Lauer ◽  
Miriam Schönbein ◽  
Sascha Lange ◽  
Stefan Welker
Keyword(s):  
Camera System ◽  
Stereo Camera

Development of Near-Diffraction Limited, Low-Cost and High-Resolution CCD Camera System for Imaging Coulter Orifices

2014 ◽  
Vol 4 (2) ◽  
pp. 54-61
Author(s):  
Sami D. Alaruri
Keyword(s):  
Imaging System ◽  
Low Cost ◽  
Ccd Camera ◽  
Image Plane ◽  
Geometric Optic ◽  
Optical Path Difference ◽  
Path Difference ◽  
Modulation Transfer ◽  
Camera System ◽  
Micro Lens

A low-cost CCD camera system for imaging Coulter orifices ranging in diameter between 20 µm and 2 mm has been developed and tested. The imaging system incorporates a 6X magnifying lens for viewing the required range of Coulter orifices and LEDs (Light emitting diodes) lamp for back illuminating the orifices. Geometric optic calculations using Zemax® for the micro-lens interfaced with the camera suggest that the spot diameter and the MTF spatial frequency at field of view equal to 0 ° and at the image plane are 5.13 µm and 271.6 lines/mm (at contrast= 37.6%), respectively. Images captured with the camera system for 20 µm, 100 µm and 2 mm diameter orifices are provided. Furthermore, a discussion for the camera micro-lens modulation transfer function, spot diagram, root-mean-square wavefront error versus field and optical path difference plots is given.

A high precision image registration method for measurement based on the stereo camera system

Optik ◽  
2020 ◽  
Vol 204 ◽  
pp. 164186
Author(s):  
Fengkai Ke ◽  
Huanping Liu ◽  
Daxing Zhao ◽  
Guodong Sun ◽  
Wan Xu ◽  
...  
Keyword(s):  
Image Registration ◽  
High Precision ◽  
Camera System ◽  
Registration Method ◽  
Stereo Camera

scholarly journals Retrieval of subvisual cirrus cloud optical thickness from limb-scatter measurements

2013 ◽  
Vol 6 (1) ◽  
pp. 105-119 ◽  
Author(s):  
J. T. Wiensz ◽  
D. A. Degenstein ◽  
N. D. Lloyd ◽  
A. E. Bourassa
Keyword(s):  
Particle Size ◽  
Optical Thickness ◽  
Imaging System ◽  
Radiative Transfer Model ◽  
Model Parameters ◽  
Transfer Model ◽  
Reconstruction Technique ◽  
Cirrus Cloud ◽  
Multiplicative Algebraic Reconstruction Technique ◽  
Cloud Particle

Abstract. We present a technique for estimating the optical thickness of subvisual cirrus clouds detected by OSIRIS (Optical Spectrograph and Infrared Imaging System), a limb-viewing satellite instrument that measures scattered radiances from the UV to the near-IR. The measurement set is composed of a ratio of limb radiance profiles at two wavelengths that indicates the presence of cloud-scattering regions. Cross-sections and phase functions from an in situ database are used to simulate scattering by cloud-particles. With appropriate configurations discussed in this paper, the SASKTRAN successive-orders of scatter radiative transfer model is able to simulate accurately the in-cloud radiances from OSIRIS. Configured in this way, the model is used with a multiplicative algebraic reconstruction technique (MART) to retrieve the cloud extinction profile for an assumed effective cloud particle size. The sensitivity of these retrievals to key auxiliary model parameters is shown, and it is shown that the retrieved extinction profile, for an assumed effective cloud particle size, models well the measured in-cloud radiances from OSIRIS. The greatest sensitivity of the retrieved optical thickness is to the effective cloud particle size. Since OSIRIS has an 11-yr record of subvisual cirrus cloud detections, the work described in this manuscript provides a very useful method for providing a long-term global record of the properties of these clouds.

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