T here exist several goals for three-dimensional (3-D) digitization and modeling of natural and c... more T here exist several goals for three-dimensional (3-D) digitization and modeling of natural and cultural heritage objects, such as for accurate detailed documentation, digital preservation and restoration, physical replicas, virtual tourism, and research or education. We focus on the detailed documentation aspect. Capturing the 3-D data requires a technique that is highly accurate; portable due to accessibility problems; low cost due to limited budgets; fast due to the usually short allowed time on the site so as not to disturb works or visitors; and flexible and scalable due to the wide variety and sizes of sites and heritage objects. It is also important that the technique captures dense 3-D data on the necessary surface elements to guarantee a realistic experience close up or to monitor surface condition over time. Furthermore, the fine geometric details are needed because even with rich texture maps, models without these details will exhibit too smooth and flat-looking surfaces or polygonized silhouettes that are easily detected by the human eye.
Visualizing how objects and sites change over time is important in applications such as heritage ... more Visualizing how objects and sites change over time is important in applications such as heritage site reconstruction, urban development, and games or entertainment. This work is an update of the technique we presented in 2006 . We also expand it to include the full sites and landscapes. We address two main challenges: reconstructing objects in different states, and the interaction and navigation within a virtual 4D world (adding time to 3D space). Most heritage sites are either modified from their original state or completely destroyed but depicted in paintings, photos, or written records. A site in its present state can be digitized in 3D using digital cameras or laser scanners. We contribute effective techniques for 3D modeling from various sources. For existing sites, a semiautomated structure from motion (SFM) approach creates a sparse model from a small number of calibrated images. Stereo matching and a depth from shading (DFS) process then add the fine details automatically. Camera poses are determined from interactively measured points followed by bundle adjustment. For destroyed sites, we use a single image technique for modeling from paintings and old photos. It differs from existing methods in that it uses various constraints and does not require vanishing lines. The technique, a revision to an earlier one [2], applies any available constraints, mainly: coordinate constraints, surface constraints, and topological constraints, in two steps: (1) calibration to determine camera internal and external parameters, and (2) 3D reconstruction. We solve first for camera parameters using constraints such as points with the same 3D coordinates. A distance is assigned between two points to define the scale. When parts of the site exist, coordinates of points on existing surfaces are also used in this calibration process. When sufficient constraint equations are formed, solution of all camera parameters is possible. In the reconstruction step, more constraints are added: shapes such as planes, cylinders, and quadrics, and topological relationships such as surfaces being perpendicular, or parallel. The technique also takes advantage of repetitions and symmetry.
This paper describes a generic technology for modeling in real time the various operations of sur... more This paper describes a generic technology for modeling in real time the various operations of surface and underground mines. Based on various sensor fusion techniques and high-speed network, a virtual reality model of a mine capable of representing not only static infrastructures but also mobile equipment such as trucks and excavators is created. The modeling technique deal with a wide range of sensors such as survey data, satellite pictures, ore concentration, machine condition indicators, video, sound, real-time GPS locator, range sensor, etc. The model created allows for every piece of information to be displayed in context allowing for a better temporal and spatial correlation of events by mine operators, planners, and supervisor. Syncrude, a Canadian mining company located in northern Alberta, is planning to use this technology, not only to understand oil sands mining processes better, but also to give decision-makers better access to the timely, accurate information from the field that they need to make informed decisions.
Virtual time travel from existing remains of a heritage site to its previous states and original ... more Virtual time travel from existing remains of a heritage site to its previous states and original condition is an educational and interesting experience and can provide better understanding of history. However, digitally reconstructing non-existing objects is a challenge. The interaction and navigation within virtual 4D worlds (adding time to 3D worlds) is also problematical due to the time dimension. In this paper we developed an approach to modelling of heritage sites that has undergone changes over the years. The method creates independent models from different types of data, such as frescos and paintings, drawings, old photos, historic descriptions, and digitization of remains, then assembles and integrates these models for an interactive presentation. Several research issues had to be addressed:
Creating geometrically correct and complete 3D models of complex environments remains a difficult... more Creating geometrically correct and complete 3D models of complex environments remains a difficult problem. Techniques for 3D digitizing and modeling have been rapidly advancing over the past few years although most focus on single objects or specific applications such as architecture and city mapping. The ability to capture details and the degree of automation vary widely from one approach to another. One can safely say that there is no single approach that works for all types of environment and at the same time is fully automated and satisfies the requirements of every application. In this paper we show that for complex environments, those composed of several objects with various characteristics, it is essential to combine data from different sensors and information from different sources. Our approach combines models created from multiple images, single images, and range sensors. It can also use known shapes, CAD, existing maps, survey data, and GPS. 3D points in the image-based models are generated by photogrammetric bundle adjustment with or without self-calibration depending on the image and point configuration. Both automatic and interactive procedures are used depending on the availability of reliable automated process. Producing high quality and accurate models, rather than full automation, is the goal. Case studies in diverse environments are used to demonstrate that all the aforementioned features are needed for environments with a significant amount of complexity.
T here exist several goals for three-dimensional (3-D) digitization and modeling of natural and c... more T here exist several goals for three-dimensional (3-D) digitization and modeling of natural and cultural heritage objects, such as for accurate detailed documentation, digital preservation and restoration, physical replicas, virtual tourism, and research or education. We focus on the detailed documentation aspect. Capturing the 3-D data requires a technique that is highly accurate; portable due to accessibility problems; low cost due to limited budgets; fast due to the usually short allowed time on the site so as not to disturb works or visitors; and flexible and scalable due to the wide variety and sizes of sites and heritage objects. It is also important that the technique captures dense 3-D data on the necessary surface elements to guarantee a realistic experience close up or to monitor surface condition over time. Furthermore, the fine geometric details are needed because even with rich texture maps, models without these details will exhibit too smooth and flat-looking surfaces or polygonized silhouettes that are easily detected by the human eye.
Visualizing how objects and sites change over time is important in applications such as heritage ... more Visualizing how objects and sites change over time is important in applications such as heritage site reconstruction, urban development, and games or entertainment. This work is an update of the technique we presented in 2006 . We also expand it to include the full sites and landscapes. We address two main challenges: reconstructing objects in different states, and the interaction and navigation within a virtual 4D world (adding time to 3D space). Most heritage sites are either modified from their original state or completely destroyed but depicted in paintings, photos, or written records. A site in its present state can be digitized in 3D using digital cameras or laser scanners. We contribute effective techniques for 3D modeling from various sources. For existing sites, a semiautomated structure from motion (SFM) approach creates a sparse model from a small number of calibrated images. Stereo matching and a depth from shading (DFS) process then add the fine details automatically. Camera poses are determined from interactively measured points followed by bundle adjustment. For destroyed sites, we use a single image technique for modeling from paintings and old photos. It differs from existing methods in that it uses various constraints and does not require vanishing lines. The technique, a revision to an earlier one [2], applies any available constraints, mainly: coordinate constraints, surface constraints, and topological constraints, in two steps: (1) calibration to determine camera internal and external parameters, and (2) 3D reconstruction. We solve first for camera parameters using constraints such as points with the same 3D coordinates. A distance is assigned between two points to define the scale. When parts of the site exist, coordinates of points on existing surfaces are also used in this calibration process. When sufficient constraint equations are formed, solution of all camera parameters is possible. In the reconstruction step, more constraints are added: shapes such as planes, cylinders, and quadrics, and topological relationships such as surfaces being perpendicular, or parallel. The technique also takes advantage of repetitions and symmetry.
This paper describes a generic technology for modeling in real time the various operations of sur... more This paper describes a generic technology for modeling in real time the various operations of surface and underground mines. Based on various sensor fusion techniques and high-speed network, a virtual reality model of a mine capable of representing not only static infrastructures but also mobile equipment such as trucks and excavators is created. The modeling technique deal with a wide range of sensors such as survey data, satellite pictures, ore concentration, machine condition indicators, video, sound, real-time GPS locator, range sensor, etc. The model created allows for every piece of information to be displayed in context allowing for a better temporal and spatial correlation of events by mine operators, planners, and supervisor. Syncrude, a Canadian mining company located in northern Alberta, is planning to use this technology, not only to understand oil sands mining processes better, but also to give decision-makers better access to the timely, accurate information from the field that they need to make informed decisions.
Virtual time travel from existing remains of a heritage site to its previous states and original ... more Virtual time travel from existing remains of a heritage site to its previous states and original condition is an educational and interesting experience and can provide better understanding of history. However, digitally reconstructing non-existing objects is a challenge. The interaction and navigation within virtual 4D worlds (adding time to 3D worlds) is also problematical due to the time dimension. In this paper we developed an approach to modelling of heritage sites that has undergone changes over the years. The method creates independent models from different types of data, such as frescos and paintings, drawings, old photos, historic descriptions, and digitization of remains, then assembles and integrates these models for an interactive presentation. Several research issues had to be addressed:
Creating geometrically correct and complete 3D models of complex environments remains a difficult... more Creating geometrically correct and complete 3D models of complex environments remains a difficult problem. Techniques for 3D digitizing and modeling have been rapidly advancing over the past few years although most focus on single objects or specific applications such as architecture and city mapping. The ability to capture details and the degree of automation vary widely from one approach to another. One can safely say that there is no single approach that works for all types of environment and at the same time is fully automated and satisfies the requirements of every application. In this paper we show that for complex environments, those composed of several objects with various characteristics, it is essential to combine data from different sensors and information from different sources. Our approach combines models created from multiple images, single images, and range sensors. It can also use known shapes, CAD, existing maps, survey data, and GPS. 3D points in the image-based models are generated by photogrammetric bundle adjustment with or without self-calibration depending on the image and point configuration. Both automatic and interactive procedures are used depending on the availability of reliable automated process. Producing high quality and accurate models, rather than full automation, is the goal. Case studies in diverse environments are used to demonstrate that all the aforementioned features are needed for environments with a significant amount of complexity.
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Papers by Sabry El-hakim