IMAGE DISTORTION CORRECTION FOR BIPRISM-BASED SINGLE-LENS STEREOVISION SYSTEM

Ph.DDOCTOR OF PHILOSOPH

Depth Recovery with Rectification using Single-Lens Prism based Stereovision System

Ph.DDOCTOR OF PHILOSOPH

Depth recovery and parameter analysis using single-lens prism based stereovision system

Ph.DDOCTOR OF PHILOSOPH

Single-lens multi-ocular stereovision using prism

Ph.DDOCTOR OF PHILOSOPH

Optimal calibration of a prism-based videoendoscopic system for precise 3D measurements

Modern videoendoscopes are capable of performing precise three-dimensional (3D) measurements of hard-to-reach elements. An attachable prism-based stereo adapter allows one to register images from two different viewpoints using a single sensor and apply stereoscopic methods. The key condition for achieving high measurement accuracy is the optimal choice of a mathematical model for calibration and 3D reconstruction procedures. In this paper, the conventional pinhole camera models with polynomial distortion approximation were analyzed and compared to the ray tracing model based on the vector form of Snell’s law. We, first, conducted a series of experiments using an industrial videoendoscope and utilized the criteria based on the measurement error of a segment length to evaluate the mathematical models considered. The experimental results confirmed a theoretical conclusion that the ray tracing model outperforms the pinhole models in a wide range of working distances. The results may be useful for the development of new stereoscopic measurement tools and algorithms for remote visual inspection in industrial and medical applications.The Russian Science Foundation (project #7-19-01355) financially supported the work. The authors thank A. Naumov, A. Shurygin and D. Khokhlov for continuous technical support

Segment-based stereo matching algorithm with rectification for single-lens bi-prism stereovision system

Ph.DDOCTOR OF PHILOSOPH

Stereo Correspondence and Depth Recovery of Single-lens Bi-prism Based Stereovision System

Ph.DDOCTOR OF PHILOSOPH

Calibration simulation for stereoscopic optical systems using optical design software

To reconstruct three-dimensional (3D) structure of objects and measure their geometric parameters using stereoscopic imaging systems, it is necessary to implement a number of image processing algorithms. For higher system efficiency, the choice of these algorithms and mathematical models should be taken into account at the stage of optical system design. We demonstrate the capabilities of optical design software to perform computer simulation of geometrical calibration for stereoscopic systems. The simulation allows comparison of mathematical models used for 3D reconstruction and estimation of 3D measurements errors caused by tolerances of optical elements, temperature variations and other factors. Using this technique, we analyze the design of prism-based stereoscopic system and show that the proposed ray tracing camera model considering pupil aberrations provides higher measurement precision. The results of computer simulation are confirmed by experiments with the self-developed stereoscopic system

Stereoscopic high dynamic range imaging

Two modern technologies show promise to dramatically increase immersion in virtual environments. Stereoscopic imaging captures two images representing the views of both eyes and allows for better depth perception. High dynamic range (HDR) imaging accurately represents real world lighting as opposed to traditional low dynamic range (LDR) imaging. HDR provides a better contrast and more natural looking scenes. The combination of the two technologies in order to gain advantages of both has been, until now, mostly unexplored due to the current limitations in the imaging pipeline. This thesis reviews both fields, proposes stereoscopic high dynamic range (SHDR) imaging pipeline outlining the challenges that need to be resolved to enable SHDR and focuses on capture and compression aspects of that pipeline. The problems of capturing SHDR images that would potentially require two HDR cameras and introduce ghosting, are mitigated by capturing an HDR and LDR pair and using it to generate SHDR images. A detailed user study compared four different methods of generating SHDR images. Results demonstrated that one of the methods may produce images perceptually indistinguishable from the ground truth. Insights obtained while developing static image operators guided the design of SHDR video techniques. Three methods for generating SHDR video from an HDR-LDR video pair are proposed and compared to the ground truth SHDR videos. Results showed little overall error and identified a method with the least error. Once captured, SHDR content needs to be efficiently compressed. Five SHDR compression methods that are backward compatible are presented. The proposed methods can encode SHDR content to little more than that of a traditional single LDR image (18% larger for one method) and the backward compatibility property encourages early adoption of the format. The work presented in this thesis has introduced and advanced capture and compression methods for the adoption of SHDR imaging. In general, this research paves the way for a novel field of SHDR imaging which should lead to improved and more realistic representation of captured scenes