Generalized Image Acquisition and Analysis

A Mathematical Model and Calibration Procedure for Galvanometric Laser Scanning Systems

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.


Interactive Volume Caustics in Single-Scattering Media

Zhao Dong, Wei Hu, Ivo Ihrke, Thorsten Grosch, Hans-Peter Seidel
In: Proceedings of I3D 2010.


Volume caustics are intricate illumination patterns formed by light first interacting with a specular surface and subsequently being scattered inside a participating medium. Although this phenomenon can be simulated by existing techniques, image synthesis is usually non-trivial and time-consuming. Motivated by interactive applications, we propose a novel volume caustics rendering method for single-scattering participating media. Our method is based on the observation that line rendering of illumination rays into the screen buffer establishes a direct light path between the viewer and the light source. This connection is introduced via a single scattering event for every pixel affected by the line primitive. Since the GPU is a parallel processor, the radiance contributions of these light paths to each of the pixels can be computed and accumulated independently. The implementation of our method is straightforward and we show that it can be seamlessly integrated with existing methods for rendering participating media. We achieve high-quality results at real-time frame rates for large and dynamic scenes containing homogeneous participating media. For inhomogeneous media, our method achieves interactive performance that is close to real-time. Our method is based on a simplified physical model and can thus be used for generating physically plausible previews of expensive lighting simulations quickly.
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author = {Hu, Wei and Dong, Zhao and Ihrke, Ivo and Grosch, Thorsten and Yuan, Guodong and Seidel, Hans-Peter},
title = {Interactive Volume Caustics in Single-Scattering Media},
booktitle = {I3D '10: Proceedings of the 2010 symposium on Interactive 3D graphics and games},
year = {2010},
pages = {109--117},
publisher = {ACM},
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