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- Abdelrehim H. Ahmed, Aly A. Farag
- 2006 IEEE Computer Society Conference on Computer…
- 2006

Lambert’s model for diffuse reflection is a main assumption in most of shape from shading (SFS) literature. Even with this simplified model, the SFS is still a difficult problem. Nevertheless, Lambert’s model has been proven to be an inaccurate approximation of the diffuse component of the surface reflectance. In this paper, we propose a new… (More)

- Abdelrehim H. Ahmed, Aly A. Farag
- 2007 IEEE Conference on Computer Vision and…
- 2007

Most of the shape from shading (SFS) algorithms have been developed under the simplifying assumptions of a Lambertian surface, an orthographic projection, and a distant light source. Due to the difficulty of the SFS problem, only a small number of algorithms have been proposed for surfaces with non-Lambertian reflectance, and among those, only very few… (More)

- Abdelrehim H. Ahmed, Aly A. Farag
- ISVC
- 2007

This paper develops a new statistical model that can be used to recover the 3D face shape from a single image taken under arbitrary lighting conditions. The proposed statistical model combines shape and image intensity information. The latter is represented by a spherical harmonics (SH) space. Given a training data set of aligned height maps of faces and… (More)

- Abdelrehim H. Ahmed, Aly A. Farag
- 2007 IEEE International Conference on Image…
- 2007

This paper presents a new method for recovering the shape of hybrid surfaces that have both diffuse reflection and specular reflection using shape from shading (SFS). The image irradiance equation has been derived as an explicit partial differential equation (PDE) under the assumptions of orthographic camera projection and distant point light source. The… (More)

- Cambron N. Carter, Rosario J. Pusateri, Dongqing Chen, Abdelrehim H. Ahmed, Aly A. Farag
- 2010 IEEE International Conference on Image…
- 2010

Accurate 3-D modeling of the human teeth helps patients avoid the discomfort of the mold process, and improves the data accuracy for oral surgeons, orthodontists and dental care personnel. Since the surface of the human tooth is almost textureless, Shape from Shading (SFS) has been successfully adopted in solving this problem. This paper evaluates 3-D tooth… (More)

- Refaat M. Mohamed, Abdelrehim H. Ahmed, Ahmed Eid, Aly A. Farag
- 2006 International Conference on Image Processing
- 2006

This paper presents a statistical learning-based solution to the camera calibration problem in which the support vector machines (SVM) are used for the estimation of the projection matrix elements. The projection matrix is obtained explicitly by using a dot product kernel in the formulation of the SVM algorithm. The mean field theory is used to approximate… (More)

- Abdelrehim H. Ahmed, Aly A. Farag, Thomas L. Starr
- 2008 15th IEEE International Conference on Image…
- 2008

This paper presents a new symmetric shape from shading (SFS) algorithm where the self-ratio image irradiance equation proposed by Zhao and Chellappa is formulated as a partial differential equation (PDE) with a Dirichlet boundary condition. This PDE is solved using the Lax-Friedrichs sweeping method. The potential of the proposed symmetric SFS algorithm is… (More)

- A. H. AHMED, K. WRIGHT
- 1986

This paper is concerned with error estimates for the numerical solution of linear ordinary differential equations by global or piecewise polynomial collocation which are based on consideration of the differential operator involved and related matrices and on the residual. It is shown that a significant advantage may be obtained by considering the form of… (More)

- A. H. Ahmed, F. A. Aldurze
- 2012 6th IEEE International Conference…
- 2012

Load frequency control as it is known means how to control the deviation in the plant frequency which happens due to a sudden changes in the power demand. the frequency is one of very important parameters which must be kept with minimum sensitivity to such a perturbations. For this reason the present work deals with studying the different types of feedback… (More)

Many different shape from shading (SFS) algorithms have emerged during the last three decades. Recently, we proposed [1] a unified framework that is capable of solving the SFS problem under various settings of imaging conditions representing the image irradiance equation of each setting as an explicit Partial Differential Equation (PDE). However, the result… (More)

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