Developments in printing ink formulations: A New Series of High Quality Printing Inks for Metals and Metal Foils
Pigment & Resin Technology, 1992
Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and... more Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and metal foils has been formulated. The suggested ink formulations are well adapted for the Lithographic and Flexographic Printing Processes. The inks are subjected to different ...
Developments in printing ink formulations: A new series of high quality printing inks for metals and metal foils
Pigment & resin technology, 1992
Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and... more Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and metal foils has been formulated. The suggested ink formulations are well adapted for the Lithographic and Flexographic Printing Processes. The inks are subjected to different ...
A detailed survey is presented of the literature on k-nearest neighbor search methods used by spa... more A detailed survey is presented of the literature on k-nearest neighbor search methods used by spatial-temporal database systems. It is an important issue in both mobile computing research and real-life applications. The scope is limited to the development of the grid indexing searching technique in terms of three different algorithms, including the well-known CPM algorithm, SEA-CNN algorithm, and CkNN algorithm. These algorithms don't make any assumptions about the movement of queries or objects. All these algorithms are compared together according to theoretical analysis with respect to data structure, required memory size and theoretical processing time consumed for each processing cycle.
A comparative study is presented on the most known k-nearest neighbor search methods used by spat... more A comparative study is presented on the most known k-nearest neighbor search methods used by spatial-temporal database systems in order to provide the advantages and limitations of each algorithm used in system simulations. The scope is limited to the development of the grid indexing searching technique in terms of three different algorithms, including the well-known CPM, SEA-CNN, and CkNN algorithm. These algorithms don't make any assumptions about the movement of queries or objects. There are a number of functions proposed, which is used in: 1) partitioning the space around the query point in case of CPM and CkNN algorithms and 2) computing minimum and maximum distances between query and cell/level. All studied algorithms are compared together according to the required number of nearest neighbors, grid granularity, location update rate, speed, and population. An accuracy comparison is done between these algorithms to estimate the performance and determine the searching region error during query processing.
Advances in Digital Photogrammetry Applications for 3D Pavement Data Collection. Invited Lecture: The 90th Annual Meeting of the Transportation Research Board, AFD20 Committee meeting, Washington, D.C., USA
Three-dimensional models are in increasing demand for design, maintenance, operations and constru... more Three-dimensional models are in increasing demand for design, maintenance, operations and construction project management. Point-clouds are the main output of automatic data collection using laser-scanners and photogrammetric technologies. Pipe-works may comprise 50% of the value of important construction projects such as industrial and research facilities. We have developed a practical and cost-effective approach, based on the Hough-transform and judicious use of domain constraints, to find, recognize and reconstruct/model 3D pipes within point-clouds fully automatically. The developed approach allows pipe growing within a 3D point-cloud. It samples the point-cloud to sequential orthogonal slices, detects pipe's cross-sections within sampled slices and grows the pipe along the cross sections centerlines. It is validated using laser-scanner data from construction of the Engineering-VI building on the University of Waterloo (UW) campus. The system works on a typical laptop. Recognition and localization results are within a few millimeters. The presented approach opens the gate to broad applications of pipe-network modeling.
Pipe-works are among the most complicated items to be tracked in the course of monitoring constru... more Pipe-works are among the most complicated items to be tracked in the course of monitoring construction project progress. Traditionally, the tracking of pipe-works progress is conducted either manually or using laser scanning technology. While laser scanning is a 3D imaging technique, and commercial software exists to construct 3D CAD models of piping based on such images, it suffers from portability, purchase cost, and other disadvantages. This paper describes digital photogrammetry technology as an alternative for pipe-works reconstruction and as a cost effective tracking tool. For validation, data was collected using a handheld digital camera to acquire images inside a new building under construction. Progress of the pipe-work networks of different types and sizes in the new building was monitored during the construction phases. In addition to the known accuracy and robustness of photogrammetry, it was found that the use of digital photogrammetry provided a practical and low-cost approach.
Comparison of Point-Cloud Acquisition from Laser-Scanning and Photogrammetry Based on Field Experimentation
ABSTRACT Laser scanning technology has been explored as a reliable and accurate method to generat... more ABSTRACT Laser scanning technology has been explored as a reliable and accurate method to generate point clouds for the purposes of 3D modelling, as-build model development, and object recognition. Despite the high cost of laser scanning equipment, the rapid scanning ability, automated data analysis and precision of this technology have enabled many cost effective applications in different fields such as construction progress tracking. Recently, photogrammetric techniques have been introduced as a more flexible and a cost-effective approach for creating point clouds, which would significantly reduce the cost of point cloud acquisition and therefore enable a broader range of applications in the construction industry. This paper presents a comparison of point-cloud generation using laser scanning and photogrammetry considering costs, portability, labour hours per collected information unit, and training expertise. The analysis was conducted in the context of point-cloud acquisition for the purposes of confirming as-built construction, and progress tracking of piping and ducting activities for an institutional construction project in Waterloo, ON. Laser scanning was performed using a FARO scanner, and photogrammetry utilized a hand-held digital camera on this project. The dialogue in this paper juxtaposes the two technologies, and seeks to identify the strengths and weaknesses of each when applied to progress tracking and as-built construction activities over the course of several months on a construction project. It was found that on one hand photogrammetry fits more a user profile for which money is an important issue, and on the other hand when training time and expertise are the issues then the laser scanning technology is preferable.
There is a growing need for tools automating the processing of as-built 3D laser scanned data, an... more There is a growing need for tools automating the processing of as-built 3D laser scanned data, and more particularly the comparison of this as-built data with planned works. This paper particularly considers the case of tracking MEP components with circular cross-sections, which essentially include pipes, and some conduits and ducts. Discrepancies between the as-built and as-planned status of pipes, conduit and ductwork result from changes that occur in the field and that are either unnoticed (human error) or not reflected in the 3D model. Previous research has shown that the Hough transform, with judiciously applied domain constraints, is a practical and cost-effective approach to find, recognize and reconstruct cylindrical MEP works within point clouds automatically. Previous research has also shown that "Scan-vs-BIM" systems that are based on the geometric alignment and comparison of as-built laser scans with as-designed BIM models can effectively recognize and identify MEP components as long as they are constructed near their as-planned locations. The research presented in this paper combines the two techniques in a unified approach for more robust automated comparison of as-built and as-planned cylindrical MEP works, thereby providing the basis for automated earned value tracking, automated percent-built-asplanned measures, and assistance for the delivery of as-built BIM models from as-designed ones. The proposed approach and its improved performance are validated using data acquired from an actual construction site. The results are very encouraging and demonstrate the added value of the proposed integrated approach over the rather simpler Scan-vs-BIM system. The two main areas of improved performance are: (1) the enabled recognition and identification of objects that are not built at their asplanned locations; and (2) the consideration for pipe completeness in the pipe recognition and identification metric.
The management of road networks requires accurate information on surface condition. Automated met... more The management of road networks requires accurate information on surface condition. Automated methods have been developed to collect road surface data, based on digital imaging systems with or without laser-profilers. While these represent state-of-the-art technology, the equipment is expensive and there are issues on accuracy and robustness. In a broad sense, the issues extend to whether user needs can be met with alternative, less-expensive technology, and whether this can be accomplished with modifications and (or) integrating a new technology with the existing equipment. This paper addresses the foregoing issues as a fundamental research and development question. It suggests that photogrammetric techniques have the potential to provide a unique and practical answer to the question. An overview and detailed formulation of the photogrammetric technology is described, with examples from experiments on road surfaces. The technical and economic advantages of the new technology are pointed out, including its potential to use consumer-grade cameras.
Developments in printing ink formulations: A New Series of High Quality Printing Inks for Metals and Metal Foils
Pigment & Resin Technology, 1992
Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and... more Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and metal foils has been formulated. The suggested ink formulations are well adapted for the Lithographic and Flexographic Printing Processes. The inks are subjected to different ...
Developments in printing ink formulations: A new series of high quality printing inks for metals and metal foils
Pigment & resin technology, 1992
Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and... more Abstract: A new series of printing inks that satisfy non-absorbent substrates, namely, metals and metal foils has been formulated. The suggested ink formulations are well adapted for the Lithographic and Flexographic Printing Processes. The inks are subjected to different ...
A detailed survey is presented of the literature on k-nearest neighbor search methods used by spa... more A detailed survey is presented of the literature on k-nearest neighbor search methods used by spatial-temporal database systems. It is an important issue in both mobile computing research and real-life applications. The scope is limited to the development of the grid indexing searching technique in terms of three different algorithms, including the well-known CPM algorithm, SEA-CNN algorithm, and CkNN algorithm. These algorithms don't make any assumptions about the movement of queries or objects. All these algorithms are compared together according to theoretical analysis with respect to data structure, required memory size and theoretical processing time consumed for each processing cycle.
A comparative study is presented on the most known k-nearest neighbor search methods used by spat... more A comparative study is presented on the most known k-nearest neighbor search methods used by spatial-temporal database systems in order to provide the advantages and limitations of each algorithm used in system simulations. The scope is limited to the development of the grid indexing searching technique in terms of three different algorithms, including the well-known CPM, SEA-CNN, and CkNN algorithm. These algorithms don't make any assumptions about the movement of queries or objects. There are a number of functions proposed, which is used in: 1) partitioning the space around the query point in case of CPM and CkNN algorithms and 2) computing minimum and maximum distances between query and cell/level. All studied algorithms are compared together according to the required number of nearest neighbors, grid granularity, location update rate, speed, and population. An accuracy comparison is done between these algorithms to estimate the performance and determine the searching region error during query processing.
Advances in Digital Photogrammetry Applications for 3D Pavement Data Collection. Invited Lecture: The 90th Annual Meeting of the Transportation Research Board, AFD20 Committee meeting, Washington, D.C., USA
Three-dimensional models are in increasing demand for design, maintenance, operations and constru... more Three-dimensional models are in increasing demand for design, maintenance, operations and construction project management. Point-clouds are the main output of automatic data collection using laser-scanners and photogrammetric technologies. Pipe-works may comprise 50% of the value of important construction projects such as industrial and research facilities. We have developed a practical and cost-effective approach, based on the Hough-transform and judicious use of domain constraints, to find, recognize and reconstruct/model 3D pipes within point-clouds fully automatically. The developed approach allows pipe growing within a 3D point-cloud. It samples the point-cloud to sequential orthogonal slices, detects pipe's cross-sections within sampled slices and grows the pipe along the cross sections centerlines. It is validated using laser-scanner data from construction of the Engineering-VI building on the University of Waterloo (UW) campus. The system works on a typical laptop. Recognition and localization results are within a few millimeters. The presented approach opens the gate to broad applications of pipe-network modeling.
Pipe-works are among the most complicated items to be tracked in the course of monitoring constru... more Pipe-works are among the most complicated items to be tracked in the course of monitoring construction project progress. Traditionally, the tracking of pipe-works progress is conducted either manually or using laser scanning technology. While laser scanning is a 3D imaging technique, and commercial software exists to construct 3D CAD models of piping based on such images, it suffers from portability, purchase cost, and other disadvantages. This paper describes digital photogrammetry technology as an alternative for pipe-works reconstruction and as a cost effective tracking tool. For validation, data was collected using a handheld digital camera to acquire images inside a new building under construction. Progress of the pipe-work networks of different types and sizes in the new building was monitored during the construction phases. In addition to the known accuracy and robustness of photogrammetry, it was found that the use of digital photogrammetry provided a practical and low-cost approach.
Comparison of Point-Cloud Acquisition from Laser-Scanning and Photogrammetry Based on Field Experimentation
ABSTRACT Laser scanning technology has been explored as a reliable and accurate method to generat... more ABSTRACT Laser scanning technology has been explored as a reliable and accurate method to generate point clouds for the purposes of 3D modelling, as-build model development, and object recognition. Despite the high cost of laser scanning equipment, the rapid scanning ability, automated data analysis and precision of this technology have enabled many cost effective applications in different fields such as construction progress tracking. Recently, photogrammetric techniques have been introduced as a more flexible and a cost-effective approach for creating point clouds, which would significantly reduce the cost of point cloud acquisition and therefore enable a broader range of applications in the construction industry. This paper presents a comparison of point-cloud generation using laser scanning and photogrammetry considering costs, portability, labour hours per collected information unit, and training expertise. The analysis was conducted in the context of point-cloud acquisition for the purposes of confirming as-built construction, and progress tracking of piping and ducting activities for an institutional construction project in Waterloo, ON. Laser scanning was performed using a FARO scanner, and photogrammetry utilized a hand-held digital camera on this project. The dialogue in this paper juxtaposes the two technologies, and seeks to identify the strengths and weaknesses of each when applied to progress tracking and as-built construction activities over the course of several months on a construction project. It was found that on one hand photogrammetry fits more a user profile for which money is an important issue, and on the other hand when training time and expertise are the issues then the laser scanning technology is preferable.
There is a growing need for tools automating the processing of as-built 3D laser scanned data, an... more There is a growing need for tools automating the processing of as-built 3D laser scanned data, and more particularly the comparison of this as-built data with planned works. This paper particularly considers the case of tracking MEP components with circular cross-sections, which essentially include pipes, and some conduits and ducts. Discrepancies between the as-built and as-planned status of pipes, conduit and ductwork result from changes that occur in the field and that are either unnoticed (human error) or not reflected in the 3D model. Previous research has shown that the Hough transform, with judiciously applied domain constraints, is a practical and cost-effective approach to find, recognize and reconstruct cylindrical MEP works within point clouds automatically. Previous research has also shown that "Scan-vs-BIM" systems that are based on the geometric alignment and comparison of as-built laser scans with as-designed BIM models can effectively recognize and identify MEP components as long as they are constructed near their as-planned locations. The research presented in this paper combines the two techniques in a unified approach for more robust automated comparison of as-built and as-planned cylindrical MEP works, thereby providing the basis for automated earned value tracking, automated percent-built-asplanned measures, and assistance for the delivery of as-built BIM models from as-designed ones. The proposed approach and its improved performance are validated using data acquired from an actual construction site. The results are very encouraging and demonstrate the added value of the proposed integrated approach over the rather simpler Scan-vs-BIM system. The two main areas of improved performance are: (1) the enabled recognition and identification of objects that are not built at their asplanned locations; and (2) the consideration for pipe completeness in the pipe recognition and identification metric.
The management of road networks requires accurate information on surface condition. Automated met... more The management of road networks requires accurate information on surface condition. Automated methods have been developed to collect road surface data, based on digital imaging systems with or without laser-profilers. While these represent state-of-the-art technology, the equipment is expensive and there are issues on accuracy and robustness. In a broad sense, the issues extend to whether user needs can be met with alternative, less-expensive technology, and whether this can be accomplished with modifications and (or) integrating a new technology with the existing equipment. This paper addresses the foregoing issues as a fundamental research and development question. It suggests that photogrammetric techniques have the potential to provide a unique and practical answer to the question. An overview and detailed formulation of the photogrammetric technology is described, with examples from experiments on road surfaces. The technical and economic advantages of the new technology are pointed out, including its potential to use consumer-grade cameras.
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Papers by Mahmoud Ahmed