Gamal Seedahmed

Gamal Seedahmed
University of Khartoum · Department of Surveying Engineering

B.Sc, M.Sc, Ph.D

About

93
Publications
85,672
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128
Citations
Introduction
Gamal Seedahmed currently works at the Department of Surveying Engineering, University of Khartoum. Gamal does research in Photogrammetry, Computer Vision, Geodesy and Surveying, Computing in Mathematics. Their current project is 'Use of Remote Sensing, RTK-GPS Topographic Mapping and GIS For Flood Risk Assessemnt For Al Gash River-Sudan.'
Additional affiliations
January 2010 - present
University of Khartoum
Position
  • Professor (Associate)
April 2007 - January 2010
University of Florida
Position
  • Professor
June 2001 - March 2007
Pacific Northwest National Laboratory
Position
  • Senior Research Scientist
Education
September 1996 - June 2001
The Ohio State University
Field of study
  • Digital Photogrammetry
September 1996 - July 2001
The Ohio State University
Field of study
  • Digital Photogrammetry
August 1987 - October 1992
University of Khartoum
Field of study
  • Surveying Engineering

Publications

Publications (93)
Article
Full-text available
Abstract Particle size distribution estimation (PSDE) is a fundamental task for heterogeneous materials characterization and modeling. This paper presents a general image-based approach for PSDE, which is called collectively “Pixel-Vernier” or PV for short. Meaningful image segmentation is the main problem to be solved for image-based PSDE. To this...
Article
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Image matching, which amounts to the automatic establishment of the correspondences between two images or more, is a fundamental problem in digital photogrammetry. It has a large number of applications such as image mosaicing and 3D surface reconstruction from images. The contributions of this paper are two folds. First, it presents a robust strate...
Article
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Although the mathematical model of 2D projective singular correlation for relative orientation was introduced to the photogrammetric community more than fifty years ago, it does not penetrate the deep practice of analytical and digital photogrammetry. On the other hand, this model is widely accepted and used in the computer vision community, which...
Article
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As is well known, a collinearity-based solution for the exterior orientation parameters (EOPs) has to deal with their initial approximation. Although this problem has been thoroughly investigated, contemporary literature continues to report it as a major obstacle. To this end, this paper proposes a general and innovative solution for the EOP approx...
Article
Full-text available
Direct solutions are very attractive because they obviate the need for initial approximations associated with non-linear solutions. The direct linear transformation (DLT) establishes itself as a method of choice for direct solutions in photogrammetry and other fields. The use of the DLT with coplanar object space points leads to a rank deficient mo...
Technical Report
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In this project a bathymetric survey was carried-out to detect location of drowned objects. A proper survey plan was designed and executed. 36 objects were detected. The results of the bathymetric survey work were rendered as a thematic map in ArcGIS for visual interpretation of drowned objects. A class of 3 categories was used to classify the dete...
Technical Report
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Our analysis and scope of work will cover the following aspects: 1. Mapping and identification of the natural drainage system that affects the road. 2. Acquisition of up-to-date satellite images for the project area 3. Estimate the width of the control section of Khor Abu Habil in the vicinity of the road. This information is very critical to evalu...
Presentation
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This presentation explains some basic operations in digital image processing. It shows some examples and the MATLAB scripts.
Presentation
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This presentation covers the following topics: A word about Automation. Definition of computer vision. Objective of digital photogrammetry. Mar’s paradigm for computational vision. Topics of this lecture. Automation of photogrammetric orientation procedures. Data driven solution. Automatic control theory. Classification of The Complexity of The Mat...
Article
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Equal weighting is a general strategy in the least squares solutions to reflect the equal contribution of observations that were obtained, for example, by identical measurement systems or similar measurement procedures or algorithms. This type of weighting can be imposed either implicitly or explicitly. Implicit weighting takes the form of an ident...
Presentation
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Generation of quick indicators for urban growth are of great importance for planning purposes such as the provision of services (Electricity, Health, Education, Food). Remote sensing image analysis can play a great role in the provision of some of these indicators. In this work, Landsat images will be used to track the urban growth of Kassala City-...
Article
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Low-level feature extraction such as lines and points (i.e. corners), forms a fundamental step in digital photogrammetry and other fields. They supply the inputs for the photogrammetric orientation procedures; and they serve as an intermediate inputs for other processes such object recognition. With the accumulation of knowledge, the research commu...
Technical Report
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The main objective of this project is to provide a solid baseline of geospatial data and information for flood risk management of Al Gash River using RTK-GPS, remote sensing, and GIS. Topographic information at centimeters level of accuracy was obtained from RTK-GPS to generate a contour map for a large part of Kassala city (85 km2) and 3D cross-se...
Presentation
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This works presents two aspects of geometrical geoid estimation, namely, model selection and critical model evaluation using Jackknife analysis.
Presentation
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This work presents an automatic approach for the extraction of co-centric circles using Hough Transform, Also it highlights some of the theoretical interpretations of Hough Transform to deepen its understanding.
Presentation
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This work presents a final year project in Dept. of Surveying Eng. @ Khartoum University in order to establish a GPS Network in Khartoum State-Sudan
Presentation
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The presentation shows several aspects of our research work in automatic matching and conflation of geospatial data. It was presented at University of Texas @ Dallas in 2008.
Technical Report
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This report provides answers to three main questions. The first one has to do with the relative accuracy between the RTK-GPS DTM and the one provided by the Dam Implementation Unit (DIU). Although we used the same control points that were used in the previous work, the results of this comparison shows that there are some difference in the orders of...
Method
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Artisanal mining is a complex economic activity that has a strong social dimension. Part of this complexity arises from the interference between the activities of the licensed mining companies and the ones from the artisanal mining. In fact, it goes side-by-side with the approved mining industry in a particular area or a block. This interference ca...
Research Proposal
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The main objective of this document is to express our interest in the execution of the pavement management system study. This document outline our methods and technologies for the pavement management study. It proposes the use of digital image processing and photogrammetry for data collection and analysis. This analysis will be followed by a proper...
Technical Report
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In this task several components of Coral building were checked for deformation and settlement. We found that there are deformations due to the cooling tower, the machinery in the mezzanine, the loading and unloading due to cars in the parking area. In addition, we found that there are irregular non-verticality in the four corners of the building, w...
Presentation
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This work presents a simple approach for the calibration of lens distortion using a 2D projective line.
Presentation
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A simple template that can be used to structure the writing of a technical report. it can be used by undergraduate and graduate students.
Presentation
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This work presents an actual implementation and experimentation of a low cost digital camera for aerial photogrammetric mapping.
Article
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Aerial and satellite images are conventionally used as a main data source for image-based geospatial data collection, map production, and updating purposes. However, it can be time consuming and costly to obtain them. Recently, Unmanned Aerial Vehicles (UAVs) are emerging as suitable technology, which has the potential to provide information with a...
Presentation
Full-text available
This presentation shows a combined approach that fuses remote sensing image analysis with bathymetric survey for pump-station site selection. In particular, the locations of islands along the River Nile were tracked over multiple yeas and used as a signal for River's banks stability. Then the bathymetric survey was conducted in the most stable loca...
Technical Report
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This report provides preliminary analysis for the topographic data for a wind farm project. This analysis generates some guidelines that need to be considered during the design and the actual setting out and installation of the project. Critical and problematic areas were identified in this preliminary analysis. The results of the topographic analy...
Presentation
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This presentation explains the basic concept and ideas behind 2D photogrammetric triangulation.
Presentation
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This presentation demonstrates the use of 2D transformations on interior orientation for a scanned aerial image.
Presentation
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This simple presentation explains the computational aspects of Least Squares Solution.
Method
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This document or template was developed to guide graduate students through the different aspects of proposal development and writing.
Research
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The main objective of this work is to evaluate the accuracy of the control or reference points as well as the accuracy of the measuring instruments in a construction project (here in this project: two sets of SOKKIA Total Station-7 seconds were used for the measurement). In particular, the practical objective of this work is to resolve a conflict b...
Presentation
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This presentation shows how to use remote sensing image analysis to improve the land leveling process. Then it shows how to move beyond the improvement process by embedding the whole approach in a monitoring framework to end up with a more general decision making process.
Presentation
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This presentation gives an overview of three measures of information theory, namely, entropy, joint entropy, and mutual information and their application in image analysis. In addition, it includes a MATLAB for these three measures. It is a part of a digital photogrammetry course at an MSc level at the University of Khartoum, Sudan.
Code
This code compute the parameters of the Direct linear Transformation (DLT) and convert them into camera parameters as well as the exterior orientation parameters (camera position and the 3 rotation angles). This code has a built-in example to demonstrate the use of the DLT.
Presentation
Full-text available
This is an updated presentation for the DLT. It has more explanation and a practical example for its implementation.
Code
This code compute the interior orientation based on an iterative Cholesky factorization.
Thesis
Full-text available
Landsat 8 images is an open-source data that is used as a spacial data source for mapping purposes and quantity measurement and other geometrically sensitive projects. ten years after design life of Landsat 8 Operational Land Imagery (OLI) ,the need to geometrically test this data increases that to test data geometrical accuracy and evaluate the ge...
Article
Full-text available
Proper integration and evaluation of an existing vertical control information with the adjustment of a new leveling network require a stepwise approach that could reveal the hidden aspects of their uncertainties or stochastic properties. The general use of the control information as fixed quantities in the adjustment of the leveling networks is a m...
Technical Report
Full-text available
The main task of this work is to measure the deflection of two steel bridges under static loading using a reflector-less total station. An axial load of 211 tons was used. The allowable deflections in the two bridges are 8.75 cm and 9.38 cm respectively. The obtained deflections for the two bridges under the stated load are 2.34 cm and 1.1 cm, whic...
Article
Full-text available
This paper presents a methodology for checking the validity of the height information of an existing contour map using RTK-GPS measurements and GIS analysis. In particular, 3D profiles were measured in the field by RTK-GPS. The same 3D profiles were extracted from a scanned and georeferenced contour map using GIS. The height information from the tw...
Technical Report
Full-text available
This report discusses the results of topographic survey for the first 18 km, which is part of the requirements of this project. This results were obtained in the first two days of this project. Although we faced several challenges during the first two days of the projects, our survey team was able to adapt to these challenges by configuring the nec...
Presentation
Full-text available
The main objective of this project is to provide a solid baseline of geospatial data and information for flood risk management of Al Gash River using RTK-GPS, remote sensing, and GIS. Topographic information at centimeters level of accuracy was obtained from RTK-GPS to generate a contour map for a large part of Kassala city (85 km2) and 3D cross-se...
Code
This code compute the Joint Histogram of a color image. This histogram can be viewed in a similar way as a co-occurrence matrix between two different colors
Presentation
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This presentation demonstrate the use of close range photogrammetry in the generation of Digital Surface Model for small areas.
Presentation
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This short presentation provides a quick comparison between two point feature extraction operators.
Presentation
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This short presentation explains the use of the co-occurrence matrix for image texture analysis.
Presentation
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This presentation shows how to form a single and joint histogram and how to extract information from them
Presentation
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This presentation shows the use of photogrammetry for 2D measurement in a practical setting
Research
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This presentation is a part of an MSC class in Digital Terrain Modeling (DTM) and it covers the foll Data collection (e.g., RTK-GPS, Total Station, Photogrammetry, etc..). DTM Generation: Mathematical representation (e.g., Data Gridding=DTM). Visualization. Filtering.Quality Control. 3D Surface Analysis., Applications.
Article
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This paper presents the results of experimental findings for beam deflection measurements under static loading using dial gauges and a reflector-less Total Station. The ultimate objective of this work is to compare the performance of the Total Station with respect to the Dial Gauge (DG). Cement bags were utilized for loading test. These loads are a...
Research
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This presentation gives an overview of the Discrete Fourier Transform (DFT). It presents the basic computational aspects of DFT as well as a MATLAB implementation of DFT of a given example. This presentation is part of a class in Digital Photogrammetry in the 5th year of surveying engineering.
Research
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This presentation demonstrates of remote sensing & GIS in groundwater exploration
Research
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This presentation was given to the Fifth Year Students in Surveying Engineering at the University of Khartoum. It is part of analytical Photogrammetry Class. It presents an automatic procedure for obtaining the initial approximation of the exterior orientation parameters. It can handle any type of rotation angles.
Research
Full-text available
The basic idea underpinning this matching technique is to compare the geometric features (points, lines, and free-from-curves) gathered from two sets according to a pre-specified geometric transformation function. A hierarchical scheme is used to reduce the computational complexity. The results of different comparisons are tracked for evalution.
Research
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The core capability of this work is to develop a proof of concept to automatically calibrate a Lidar scanning system by modeling the existing systematic errors. This concept will address the intrinsic nature of Lidar data collection and its impact on calibration. In addition the proposed concept will investigate the underlying cause of the systemat...
Research
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This document presents a methodology for automatic extraction of Digital Elevation Models from High Resolution images.
Research
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At the present time, the algorithms involved in photogrammetric activities are changing substantially. Photogrammetric activities are expanding to accommodate features other than points, such as straight-line, in the photogrammetric solution. Along this line of expansion, in this study, conic sections (circles and ellipses) were formulated as compu...
Research
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Digital terrain modeling is an important task in several geospatial information applications. Digital Terrain Models (DTMs) are used, for instance, for orthophotos generation, 3-D city modeling, Flight simulation, and virtual battlefield training. Recently, Digital Earth (DE) (e.g., Microsoft Virtual Earth and Google’s Earth) is being explored and...
Research
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To realize the full potential of open sources media on the Internet, such as Google Earth and Bing Maps, in the domain of geospatial information applications, this paper presents the results of a rapid and affordable integrated solution for geospatial information collection. Geospatial information here refers to products such as digital maps, 3D su...
Research
Full-text available
Direct solutions are very attractive because they obviate the need for initial approximations associated with non-linear solutions. The Direct Linear Transformation (DLT) establishes itself as a method of choice for direct solutions in photogrammetry and other fields. The use of the DLT with coplanar object space points leads to a rank deficient mo...
Research
Full-text available
This presentation was given at the Pacific Northwest National Lab in 2007. It shows part of my research work in automatic matching of geospatial data sets. It formulates the 2D similarity transformation as a Hough Transformation problem for automatic alignment of image-to-image, image-to-vector, and vector-to-vector data sets.
Research
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This presentation was given to the students at the Fifth Year of Surveying Engineering at the University of Khartoum. This presentation explains the basics of artificial neural networks (ANN) and their uses in supervised classification. In particular, it demonstrates the use of ANN on color images for vegetation extraction.
Research
Full-text available
It is a presentation that was given to the student in the Fifth year of Surveying Engineering in an analytical photogrammetry class. It explains a linear model of that relates the image coordinates to the ground coordinates. It is well known in the photogrammetric community as DLT.
Research
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It is presentation that was given to the Fifth Year students, surveying engineering, in an analytical photogrammetry class at the University of Khartoum. It explains the issues of 3D rotation with MATLAB implementation.
Research
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This presentation was given the Fifth Year Students in Surveying Engineering as a part of Analytical Photogrammetry class. It explains the geometry and the estimation of the Exterior Orientation Parameters by the use of the Collinearity Condition Equations. Also it shows a procedure on how to obtain the initial approximations for the Exterior Orien...
Technical Report
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On April-8th- 2015, the railway short span bridge that crosses Al Gamauh Ave in the North-South direction was exposed to a fire accident; and this is due to a friction of a gas tanker with the bottom of this bridge. Sudan Railways Corporation (SRC) called for loading tests to assess the impact of this fire on the bridge components. The tests consis...
Technical Report
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This work is concerned with the collection of samples from Saruss Block and their laboratory analysis. The ultimate objective of the this work is to rank and to delineate areas of highest potential and priority to start small scale exploration and mining in the time being; and to facilitate parallel work and activities of proper large scale explora...
Data
This presentation was presented in a digital photogrammetry. It gives an overview for the discrete Fourier Transform and its applications in geospatial field
Article
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Accurate, robust, and automatic image registration is a critical task in many typical applications, which employ multi-sensor and/or multi-date imagery information. In this paper we present a new approach to automatic image registration, which obviates the need for feature matching and solves for the registration parameters in a Hough-like approach...
Article
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As the availability of geospatial data increases, there is a growing need to match these datasets together. However, since these datasets often vary in their origins and spatial accuracy, they frequently do not correspond well to each other, which create multiple problems. To accurately align with imagery, analysts currently either: 1) manually mov...
Technical Report
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This presentation explains the computational aspects of image convolution and the practical issues of a moving window.
Article
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This paper describes a novel method for determining the absolute orientation of lidar point clouds using GPS measurements from two antennas firmly mounted on the optical head of a lidar scanner. The solution is linear and is derived from the non-linear georeferencing model by exploiting the properties of the skew-symmetric matrix. Simulation and re...
Data
This data set contains 3 overlapping aerial images that were taken by a low cost digital camera. These images can be used by the research community for testing.
Article
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The variability of panchromatic and multispectral images, vector data (maps) and DEM models is growing. Accordingly, the requests and challenges are growing to correlate, match, co-register, and fuse them. Data to be integrated may have inaccurate and contradictory geo-references or not have them at all. Alignment of vector (feature) and raster (im...
Conference Paper
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Registration and alignment of feature (e.g., vector) and raster geospatial data is a difficult and time-consuming process when performed manually. This paper presents an approach for vector-to-raster registration. Candidate features are auto-extracted and vectorized from imagery, which are the basis to compare against existing vector layer(s) to be...
Article
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Often text and imagery contain information that must be combined to solve a problem. One approach begins with transforming the raw text and imagery into a common structure that contains the critical information in a usable form. This paper presents an application in which the imagery of vehicles and the text from police reports were combined to dem...
Presentation
Full-text available
In this work we present preliminary results of a new methodology for texture characterization. This methodology is grounded on scale-space representation and mutual information tracking across the scale-space. Scale-space mutual information seeks to e