Showing papers on "Orientation (computer vision) published in 1970"

Studies of Resolution in a Bragg Imaging System

Abstract: This paper presents the results of experiments that were performed to investigate the resolution capabilities of a Bragg imaging system using a cylindrically convergent light beam. The usual images formed with such a system show up as silhouetts of the objects being imaged. These silhouettes are superimposed on a light background, which constitutes the visual representation of the incident sound field. The Rayleigh criterion governs the resolution for thin cylindrical objects oriented parallel to the direction of the convergence line of the light beam. For orientation at right angles to this direction, the resolution is of quite a different character. The experimental resolution capabilities for both directions are presented in this paper and are compared with theoretical predictions. Resolution data is also presented for the case of dark‐field imaging, i.e., where the objects appear as bright images on a dark background. In addition, experiments were performed to determine the loss of resolution resulting from the introduction of optically opaque plates between the scattering object and the light‐sound interaction region.

Hypercatadioptric Line Images for 3D Orientation and Image Rectification

Abstract: In central catadioptric systems 3D lines are projected into conics. In this work we present a new approach to extract conics in the raw catadioptric image, which correspond to projected straight lines in the scene. Using the internal calibration and two image points we are able to compute analytically these conics which we name hypercatadioptric line images. We also perform an exhaustive analysis on the elements that can affect the conic extraction accuracy and its error propagation. Besides that, we exploit the presence of parallel lines in man-made environments to compute the dominant vanishing points (VPs) in the omnidirectional image. In order to obtain the intersection of two of these conics we analyze the self-polar triangle common to this pair. With the information contained in the vanishing points we are able to obtain the 3D orientation of the catadioptric system. This method can be used either in a vertical stabilization system required by autonomous navigation or to rectify images required in applications where the vertical orientation of the catadioptric system is assumed. We use synthetic and real images to test the proposed method. We evaluate the 3D orientation accuracy with a ground truth given by a goniometer and with an inertial measurement unit (IMU). We also test our approach performing vertical and full rectifications in sequences of real images.

Automatic image rotator for micro-image reader-printer

Abstract: Apparatus for automatically rotating an enlarged microfilm image through an angle of 90 DEG from a first orientation as projected onto a projection screen to a second orientation as projected onto the image plane of a printout station. The image rotating apparatus includes a motor driven prism controlled by a pair of electrical switches actuated by a member secured to the prism carrier which defines limit positions of the prism to automatically effect reorientation of the projected image responsive to actuation of the printing cycle mechanism.

Brain Magnetic Resonance Image Lateral Ventricles Deformation Analysis and Tumor Prediction

Abstract: Brain tumor detection is still a challenge in the field of brain compute-aided diagnosis. In the brain Magnetic Resonance Images (MRI), the correlation between lateral ventricles deformations and tumor existence has been found useful in brain tumor detection and prediction. To retrieve the lateral ventricles deformation data for further statistical analysis and processing, a new method has been proposed in this paper to analyze the deformation of ventricles. Firstly, in this method, the boundaries of the lateral ventricles are segmented, pixels on the boundary are sampled, and a nonlinear interpolation method based on Thin Plate Spline (TPS) is conducted to create a more accurate template image for each specific case, followed by the application and performance comparison between TPS with Radial Basis Function Neural Networks (RBF-NN) and Radon Transform (RT) on the extracted Skeleton of the boundary of the ventricles for locating the optimal orientation of the image through iterative image rotation. The reorienting facilitates the final step of deformation analysis whereby the reoriented ventricles are analyzed based on the displacement values obtained from the TPS of the sampled template and the diagnostic lateral ventricle. By comparing with several real cases, our experimental results suggest that this method is effective and relevant in ventricles deformation analysis and prediction of tumor location. The performance comparison results also suggest that using RT on Skeleton is an efficient method in locating the optimal orientation where the results show that the computing speed is at least more than 100 times faster than using TPS and RBF-NN.