Generalized Image Acquisition and Analysis

Synchronization and Rolling Shutter Compensation for Consumer Video Camera Arrays

Two major obstacles to the use of consumer camcorders in computer vision applications are the lack of synchronization hardware, and the use of a "rolling" shutter, which introduces a temporal shear in the video volume. We present two simple approaches for solving both the rolling shutter shear and the synchronization problem at the same time. The first approach is based on strobe illumination, while the second employs a subframe warp along optical flow vectors. In our experiments we have used the proposed methods to effectively remove temporal shear, and synchronize up to 16 consumer-grade camcorders in multiple geometric configurations.


Eikonal Rendering: Efficient Light Transport in Refractive Objects

Ivo Ihrke, Gernot Ziegler, Art Tevs, Christian Theobalt, Marcus Magnor, Hans-Peter Seidel
In: Proceedings of SIGGRAPH 2007.


We present a new method for real-time rendering of sophisticated lighting effects in and around refractive objects. It enables us to realistically display refractive objects with complex material properties, such as arbitrarily varying refraction index, inhomogeneous attenuation, as well as spatially-varying anisotropic scattering and reflectance properties. User-controlled changes of lighting positions only require a few seconds of update time. Our method is based on a set of ordinary differential equations derived from the eikonal equation, the main postulate of geometric optics. This set of equations allows for fast casting of bent light rays with the complexity of a particle tracer. Based on this concept, we also propose an efficient light propagation technique using adaptive wavefront tracing. Efficient GPU implementations for our algorithmic concepts enable us to render visual effects that were previously not reproducible in this combination in real-time.
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author = "I.~Ihrke and G.~Ziegler and A.~Tevs and C.~Theobalt and M.~Magnor and H.-P.~Seidel",
title = "Eikonal Rendering: Efficient Light Transport in Refractive Objects",
journal = "ACM Trans. on Graphics (Siggraph'07)",
year = "2007",
month = aug,
pages="to appear"
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