Browsing by Subject "Computer graphics equipment"

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Open Access
Quality comparison and acceleration for digital hologram generation method based on segmentation
(IEEE, 2009) Kang, Hoonjong; Yaraş, Fahri; Onural, Levent
A holographic fringe pattern generation methods is based on Fraunhofer diffraction and subsequent segmentation and approximation of the fringe pattern. Several modifications of the original algorithm are already proposed to improve the quality of reconstructions. We compare the quality of to the reconstructed images from different versions of this algorithm by taking the reconstructions from the Fresnel hologram as a reference. Since, there is not any generally accepted objective quality assessment method for such reconstructions, we used some experimental methods such as intensity spread over the reconstructed images, total noise power, and peak-signal-to-noise for comparison. Then we chose the best performing algorithm in terms of ireconstruction quality, and developed a GPU-based implementation to accelerate the computation speed. The quality of the resultant reconstructions is comparable to reconstructions from Fresnel holograms; much higher speed is achieved due to multi-GPU implemetation.
Open Access
Stereoscopic urban visualization based on graphics processor unit
(S P I E - International Society for Optical Engineering, 2008-09) Yilmaz, T.; Güdükbay, Uğur
We propose a framework for the stereoscopic visualization of urban environments. The framework uses occlusion and view-frustum culling (VFC) and utilizes graphics hardware to speed up the rendering process. The occlusion culling is based on a slice-wise storage scheme that represents buildings using axis-aligned slices. This provides a fast and a low-cost way to access the visible parts of the buildings. View-frustum culling for stereoscopic visualization is carried out once for both eyes by applying a transformation to the culling location. Rendering using graphics hardware is based on the slice-wise building representation. The representation facilitates fast access to data that are pushed into the graphics procesing unit (GPU) buffers. We present algorithms to access this GPU data. The stereoscopic visualization uses off-axis projection, which we found more suitable for the case of urban visualization. The framework is tested on large urban models containing 7.8 million and 23 million polygons. Performance experiments show that real-time stereoscopic visualization can be achieved for large models. © 2008 Society of Photo-Optical Instrumentation Engineers.