Generalized Image Acquisition and Analysis

An evaluation of optical flow algorithms for background oriented schlieren imaging

The background oriented schlieren method (BOS) allows for accurate flow measurements with a simple experimental configuration. To estimate per-pixel displacement vectors between two images, BOS systems traditionally borrow window-based algorithms from particle image velocimetry. In this paper, we evaluate the performance of more recent optical flow methods in BOS settings. We also analyze the impact of different background patterns, suggesting the use of a pattern with detail at many scales. Experiments with both synthetic and real datasets show that the performance of BOS systems can be significantly improved through a combination of optical flow algorithms and multiscale background.


A Mathematical Model and Calibration Procedure for Galvanometric Laser Scanning Systems

Alkhazur Manakov, Hans-Peter Seidel, Ivo Ihrke
In: Vision, Modeling, and Visualization (VMV 2011)


Laser galvanometric scanning systems are commonly used in various fields such as three dimensional scanning, medical imaging, material processing, measurement devices and laser display systems. The systems of such kind suffer from distortions. On top of that they do not have a center of projection, which makes it impossible to use common projector calibration procedures. The paper presents a novel mathematical model to predict the image distortions caused by galvanometric mirror scanning systems. In addition, we describe a calibration procedure for recovering its intrinsic and extrinsic parameters.


author = {Alkhazur Manakov and Hans-Peter Seidel and Ivo Ihrke},
title = "{A Mathematical Model and Calibration Procedure for Galvanometric Laser Scanning Systems}",
booktitle = {Proceedings of VMV},
pages = "207--214",
year = {2011},
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