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Author

Sabry F. El-Hakim

Other affiliations: Siemens
Bio: Sabry F. El-Hakim is an academic researcher from National Research Council. The author has contributed to research in topics: Photogrammetry & Cultural heritage. The author has an hindex of 27, co-authored 64 publications receiving 3343 citations. Previous affiliations of Sabry F. El-Hakim include Siemens.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the main problems and the available solutions for the generation of 3D models from terrestrial images are addressed, and the full pipeline is presented for 3D modelling from terrestrial image data, considering the different approaches and analyzing all the steps involved.
Abstract: In this paper the main problems and the available solutions are addressed for the generation of 3D models from terrestrial images. Close range photogrammetry has dealt for many years with manual or automatic image measurements for precise 3D modelling. Nowadays 3D scanners are also becoming a standard source for input data in many application areas, but image-based modelling still remains the most complete, economical, portable, flexible and widely used approach. In this paper the full pipeline is presented for 3D modelling from terrestrial image data, considering the different approaches and analysing all the steps involved.

848 citations

Patent
Lee H. Gerig1, Sabry F. El-Hakim1
08 Oct 1993
TL;DR: In this paper, a remote sensing system for real-time monitoring of patient position which can report variations in patient setup from day to day as well as motion during individual treatments is presented.
Abstract: The present invention is a remote sensing system for real time monitoring of patient position which can report variations in patient setup from day to day as well as motion during individual treatments In particular, an embodiment of the present invention includes: (a) a source of radiation for applying radiation to a patient; (b) targets affixed to the patient for reflecting radiation impinging thereon; (c) two cameras and a computer for detecting the reflected radiation and for determining the current position of the targets in three-dimensional space; (d) a data store for storing the position of the targets; (e) the computer also serving to compare the current position of the targets with positions stored in the data store; and (f) a display for displaying indicators whenever differences between the current position and the stored position exceed tolerances stored in the data store

288 citations

Patent
16 Sep 1997
TL;DR: In this paper, a mobile mapping system is designed to generate a geometrically precise 3D detailed model of an unknown indoor environment by adjusting a plurality of images simultaneously, provided a sufficient overlap between two-dimensional intensity images and combining such with three-dimensional range images.
Abstract: A mobile mapping system is designed to generate a geometrically precise three-dimensional detailed model of an unknown indoor environment. There is no limit on the distance the mobile system may travel, nor on the type of details that can be mapped. The same design is used for environments ranging from simple office hallways to long winding underground mine tunnels. Surfaces and features can be mapped from images acquired by a unique configuration of different types of optical imaging sensors and positioning devices. This configuration ensures that all the information required to reconstruct the three-dimensional environment is included in the collected images. Provided a sufficient overlap between two-dimensional intensity images and combining such with three-dimensional range images, the method reconstructs an environment by adjusting a plurality of images simultaneously.

252 citations

Journal ArticleDOI
TL;DR: This approach integrates several technologies based on the experience over more than a decade of trying to accurately and completely model large-scale heritage monuments and sites to model a highly detailed structure or site at various levels of detail.
Abstract: Many cultural heritage applications require 3D reconstruction of real-world objects and scenes. Over the past few years, it has become increasingly common to use 3D digitization and modeling for this purpose. This is mainly due to advances in laser-scanning techniques, 3D modeling software, image-based modeling techniques, computer power, and virtual reality. Our approach integrates several technologies based on our experience over more than a decade of trying to accurately and completely model large-scale heritage monuments and sites. Using both interactive and automatic techniques, we can model a highly detailed structure or site at various levels of detail. We use image-based modeling for basic shape and structural elements, and laser scanning for fine details and sculpted surfaces. To present the site in its proper context, we use image-based rendering for landscapes and surroundings. To apply this approach, we created hundreds of models from sites all over the world for documentation, walk-through movies, and interactive visualization. The results were compelling and encouraging.

246 citations

Journal ArticleDOI
TL;DR: A multistage image-based modeling approach that requires only a limited amount of human interactivity and is capable of capturing the fine geometric details with similar accuracy as close-range active range sensors is proposed.
Abstract: In this article developments and performance analysis of image matching for detailed surface reconstruction of heritage objects is discussed. Three dimensional image-based modeling of heritages is a very interesting topic with many possible applications. In this article we propose a multistage image-based modeling approach that requires only a limited amount of human interactivity and is capable of capturing the fine geometric details with similar accuracy as close-range active range sensors. It can also cope with wide baselines using several advancements over standard stereo matching techniques. Our approach is sequential, starting from a sparse basic segmented model created with a small number of interactively measured points. This model, specifically the equation of each surface, is then used as a guide to automatically add the fine details. The following three techniques are used, each where best suited, to retrieve the details: 1) for regularly shaped patches such as planes, cylinders, or quadrics, we apply a fast relative stereo matching technique. 2) For more complex or irregular segments with unknown shape, we use a global multi-image geometrically constrained technique. 3) For segments unsuited for stereo matching, we employ depth from shading (DFS). The goal is not the development of a fully automated procedure for 3D object reconstruction from image data or a sparse stereo approach, but we aim at the digital reconstruction of detailed and accurate surfaces from calibrated and oriented images for practical daily documentation and digital conservation of wide variety of heritage objects.

131 citations


Cited by
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Journal ArticleDOI
TL;DR: The Structure-from-Motion (SfM) method as mentioned in this paper solves the camera pose and scene geometry simultaneously and automatically, using a highly redundant bundle adjustment based on matching features in multiple overlapping, offset images.

2,901 citations

Proceedings ArticleDOI
01 Jul 2000
TL;DR: A hardware and software system for digitizing the shape and color of large fragile objects under non-laboratory conditions and the largest single dataset is of the David - 2 billion polygons and 7,000 color images.
Abstract: We describe a hardware and software system for digitizing the shape and color of large fragile objects under non-laboratory conditions Our system employs laser triangulation rangefinders, laser time-of-flight rangefinders, digital still cameras, and a suite of software for acquiring, aligning, merging, and viewing scanned data As a demonstration of this system, we digitized 10 statues by Michelangelo, including the well-known figure of David, two building interiors, and all 1,163 extant fragments of the Forma Urbis Romae, a giant marble map of ancient Rome Our largest single dataset is of the David - 2 billion polygons and 7,000 color images In this paper, we discuss the challenges we faced in building this system, the solutions we employed, and the lessons we learned We focus in particular on the unusual design of our laser triangulation scanner and on the algorithms and software we developed for handling very large scanned models

1,675 citations

Book
01 Jan 2003
TL;DR: This article provides a comprehensive introduction into the field of robotic mapping, with a focus on indoor mapping, and describes and compares various probabilistic techniques, as they are presently being applied to a vast array of mobile robot mapping problems.
Abstract: This article provides a comprehensive introduction into the field of robotic mapping, with a focus on indoor mapping. It describes and compares various probabilistic techniques, as they are presently being applied to a vast array of mobile robot mapping problems. The history of robotic mapping is also detailed, along with an extensive list of open research problems.

1,584 citations

Journal ArticleDOI
TL;DR: Results show scarce BIM implementation in existing buildings yet, due to challenges of (1) high modeling/conversion effort from captured building data into semantic BIM objects, (2) updating of information in BIM and (3) handling of uncertain data, objects and relations in B IM occurring inexisting buildings.

1,499 citations

Patent
14 Nov 2011
TL;DR: In this paper, an image guided catheter navigation system for navigating a region of a patient includes an imaging device, a tracking device, and a controller, as well as a display that displays the image of the region with the catheter superimposed onto the image at the current location.
Abstract: An image guided catheter navigation system for navigating a region of a patient includes an imaging device, a tracking device, a controller, and a display. The imaging device generates images of the region of the patient. The tracking device tracks the location of the catheter in the region of the patient. The controller superimposes an icon representing the catheter onto the images generated from the imaging device based upon the location of the catheter. The display displays the image of the region with the catheter superimposed onto the image at the current location of the catheter.

1,278 citations