Papers by Abderrahim Saaidi
International Review on Computers and Software
The technique of cone tracing, used for rendering very detailed surface in real-time, is certainl... more The technique of cone tracing, used for rendering very detailed surface in real-time, is certainly among the best techniques at the present time. But unfortunately, in its two versions, conservative and relaxed, this technique suffers from a heavy pre-processing having a quadratic complexity. Moreover, the processing of non-square textures remains a problem. In this article we introduce a new linear complexity algorithm for generating relaxed cone maps. Additionally, we propose to use the Height Distributional Distance Transform HDDT for creating conservative cone maps. The HDDT is a linear algorithm used in terrain rendering. We also introduce a new method for supporting non-square textures using an elliptical rectification. Finally, we suggest using the cones’ radius instead of their ratio. This eliminates the constraint limiting the cones’ apex angle to π/4 which significantly improves the performance of the cone tracing technique
Journal of Emerging Technologies in Web Intelligence, 2014
The Visual Computer, 2014
In this article, we are interested in the utilization of an unknown planar scene for the CCD came... more In this article, we are interested in the utilization of an unknown planar scene for the CCD camera selfcalibration having a constant focal distance. The originality of our method resides in the matching utilization in three images to estimate all matrixes of a parallelogram projection that are exploited with homographies between images to estimate the camera intrinsic parameters. The experimental results show the robustness of our algorithms, in term of stability and convergence.
Extruded shapes and patterns are widely used by graphic designers to increase the visual richness... more Extruded shapes and patterns are widely used by graphic designers to increase the visual richness and realism of 3D models and virtual environments in general. However, the traditional approach that uses polygonal mesh is inappropriate for real-time rendering, in which, just a limited number of graphic primitives can be processed. Hence the interest of using per-pixel approaches. In this paper, we introduce a new imagebased technique for rendering extruded details and shapes. We use a single RGBA texture in which we store a binary shape, its Euclidean Distance Transform (EDT), and the two components of the EDT gradient. The rendering algorithm is based on a raytracing like procedure, performed in texture space. The use of the EDT allows skipping empty space and thus, minimizes the number of ray-tracing steps. Per-pixel extrusion mapping produces very convincing results, and runs at interactive frame rates.
This paper presents a new method for matching points of interest in stereoscopic. A self-calibrat... more This paper presents a new method for matching points of interest in stereoscopic. A self-calibration is realized by using points of interest on both images in order to estimate the fundamental matrix from which we can compute both projected matrices related to each camera. We propose a robust and fast rectification technique for matching points of interest in order to simplify the research on epipolar line. Resemblance measure based on ZNCC (Zero mean Normalized Cross Correlation). Our matching scheme is evaluated using stereo images consisting of many points, with regularization using homography and fundamental matrix. The results obtained clearly show the relevance of our approach.
In this article, we are interested in the camera self-calibration from three views of a 3-D scene... more In this article, we are interested in the camera self-calibration from three views of a 3-D scene. The originality of our method resides in the new technique used to estimate the homography of the plane at infinity by the minimization of a non-linear cost function that is based on a particular motion of the camera "translation and small rotation". Our approach also permits to calculate the camera parameters and the depths of interest points detected in the images. Experimental results demonstrate the performance of our algorithms, in term of precision and convergence.
ACM Transactions on Graphics, 2010
Extrusion, bevel, chamfer, and lathe tools are widely used in a large variety of computer graphic... more Extrusion, bevel, chamfer, and lathe tools are widely used in a large variety of computer graphics applications such as architectural designs and industrial prototyping of manufactured goods. However, such modeling is usually based on polygonal meshes which often require a considerable amount of graphics primitives. In this article, we present a new image-based approach for rendering extruded and revolved surfaces. We use only a single RGBA texture which stores a binary map (i.e. The profile curve), its Euclidean distance transform, and the two components of the unit gradient vector of the distance fields. All rendering algorithms are based on a ray-tracing procedure performed in texture space. The use of the distance fields allows culling of empty space and thus minimizes the number of ray-tracing steps. The extrusion and revolution mapping techniques produce very convincing models, and both are rendered at interactive frame rates.
In this issue serveral articles are presented theu are; P1151011026 by R. Satyabama and S. Annadu... more In this issue serveral articles are presented theu are; P1151011026 by R. Satyabama and S. Annadurai on “Spatial Adaptive Prediction for Lifting Scheme in Image Compression” P1151023081 by M. Amrouch and A. Rachidi and M. El Yassa and D. Mammass on “Handwritten Amazigh Character Recognition Based On Hidden Markov Models”, P1151030176 by A.El abderrahmani and A.Saaidi and K.Satori on “Robust Technique for Self-Calibration of Cameras based on a Circle” P1151032183 by Christian Hopfgartner and Ingo Scholz and Martin Gugat and Günter Leugering and Joachim Hornegger on “Intensity-based 3-D Reconstruction with Non-linear Optimization” P1150951944 by Ming Yan and Robert Laganière and Gerhard Roth on “Estimation of Camera Positions over Long Image Sequences” P1151033197 by Bremananth R and Veerabadran C S on “An investigation on Off-line Bank Document Images Localization and Recognition using WBDP, Texture and Perceptual Features” P1151036290 by T.Sridevi and Y.Ramadevi and V.Vijaya Kumar on “SECURE WATERMARKING BASED ON SVD AND WAVELETS”
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Papers by Abderrahim Saaidi