Opti-acoustic stereo imaging

Saç, Hakan
In this thesis, opti-acoustic stereo imaging, which is the deployment of two-dimensional (2D) high frequency imaging sonar with the electro-optical camera in calibrated stereo configuration, is studied. Optical cameras give detailed images in clear waters. However, in dark or turbid waters, information coming from electro-optical sensor is insufficient for accurate scene perception. Imaging sonars, also known as acoustic cameras, can provide enhanced target details under these scenarios. To illustrate these visibility conditions, a 2D high frequency imaging sonar simulator as well as an underwater optical image simulator is developed. A computationally efficient algorithm is also proposed for the post-processing of the returned sonar signals. Where optical visibility allows, integration of the sonar and optical images effectively provides binocular stereo vision capability and enables the recovery of three-dimensional (3D) structural information. This requires solving the feature correspondence problem for these completely different sensing modalities. Geometrical interpretation of this problem is examined on the simulated optical and sonar images. Matching the features manually, 3D reconstruction performance of opti-acoustic system is also investigated. In addition, motion estimation from opti-acoustic image sequences is studied. Finally, a method is proposed to improve the degraded optical images with the help of sonar images. First, a nonlinear mapping is found to match local the features in opti-acoustical images. Next, features in the sonar image is mapped to the optical image using the transformation. Performance of the mapping is evaluated for different scene geometries.


Turkmenoglu, Mustafa; Sengul, Orhan; Demircioglu, Erdem (2013-06-01)
Signal to Noise Ratio (SNR) is a metric used to link the image quality and radiometric performance of the remote sensing imaging systems. It is one of the remote sensing imaging system's design parameters that represents the image quality. SNR calculation and analysis should be carried out at design phase of remote sensing imaging systems. This calculation and analysis are crucial for confirmation of design success. It is important to show that the light flux reaching the sensor and the generated electrons ...
KIRAGI, H; Ersak, Aydın (1994-04-14)
In this paper an object recognition and localization system based on ultrasonic range imaging to be used in optically opaque environments is introduced. The system is especially designed for robotics applications. The ultrasonic image is acquired by scanning ultrasonic transducers in two dimensions above the area where objects are located. The features that are used for recognition and localization processes are extracted from the outermost boundaries of the objects present in the input scene. Experimental ...
3D Object Modeling by Structured Light and Stereo Vision
Ozenc, Ugur; Tastan, Oguzhan; GÜLLÜ, MEHMET KEMAL (2015-05-19)
In this paper, we demonstrate a 3D object modeling system utilizing a setup which consists of two CMOS cameras and a DLP projector by making use of structured light and stereo vision. The calibration of the system is carried out using calibration pattern. The images are taken with stereo camera pair by projecting structured light onto the object and the correspondence problem is solved by both epipolar constraint of stereo vision and gray code constraint of structured light. The first experimental results s...
Effective structure-from-motion for hybrid camera systems
Baştanlar, Yalın; Temizel, Alptekin; Yardımcı, Yasemin; STURM, Peter (2010-08-26)
We describe a pipeline for structure-from-motion with mixed camera types, namely omni directional and perspective cameras. The steps of the pipeline can be summarized as calibration, point matching, pose estimation, triangulation and bundle adjustment. For these steps, we either propose improved methods or modify existing perspective camera methods to make the pipeline more effective and automatic when employed for hybrid camera systems.
Radiometric Camera Calibration of BiLSAT Small Satellite: Preliminary Results
Frıedrıch, Jurgen; Leloğlu, Uğur Murat; Tunalı, Erol (2006-02-16)
The studies on radiometric camera calibration of multispectral camera of the BiLSAT satellite is presented in this work. During the study, various dark images and flat-field images have been taken, and deviations from ideal has been investigated. Various sources of error have been studied and the non-homogeneous response of the CCD is explicitly modeled. Images have been corrected according to the models and the results have been discussed.
Citation Formats
H. Saç, “Opti-acoustic stereo imaging,” M.S. - Master of Science, Middle East Technical University, 2012.