The representation of the Earth' topography in a 3D digital format is a vital constituent in a wi... more The representation of the Earth' topography in a 3D digital format is a vital constituent in a wide range of geographic, geomatics, environmental, and engineering activities. However, the accuracy of such representations could define its applicability and validity for a specific utilization. This chapter presents an analysis of four open-source Global Digital Elevation Models (GDEMs) and compares them on two topographic profiles (nearly flat, and hills regions) for mapping and geomatics applications in two countries. The main goal is to determine whether GDEMs-based heights, contour intervals, slopes, and topographic profiles are accurate for all topographic map scales, which is a significant problem in mapping operations. For the purpose of illustrating flat and moderate-topography patterns, two case studies-the Nile delta in Egypt and Makkah city in Saudi Arabia-have been used. The investigated GDEMs include the most-recent released models: ASTER v.3, ACE 2, SRTMGL1 v. 3, and NASADEM_HGT v.1 released in 2019 and 2020 with spatial resolutions of 1 and 3 arc seconds. There are 540 accurate Ground Control Points (GCP) available in the Nile delta and 175 in Makkah. It has been determined based on the available datasets in two study locations that the accuracy of investigated GDEMs over known checkpoints range from 2.5 and 5.1 meters in the Nile delta region, while it varies between 5.1 and 8.0 meters in the Makkah area. This suggests that the use of GDEMs in topographic mapping varies greatly between spatial areas that are flat and those that are hilly. Therefore, it is advised against utilizing GDEMs to create topographic maps at scales of 1: 25,000 or greater in flat areas and 1: 50,000 or greater in hilly areas. Additionally, the achieved results demonstrated that throughout cross sections up to 30 kilometers in length, no GDEM-based slope matches the real slopes from known GCP. This leads to the conclusion that GDEMs are not the appropriate heights' source for topographic mapping at
شرح مبسط لطلاب المدارس الثانوية للتعرف علي علوم و تقنيات الكارتوجرافيا و الاستشعار عن بعد و نظم ا... more شرح مبسط لطلاب المدارس الثانوية للتعرف علي علوم و تقنيات الكارتوجرافيا و الاستشعار عن بعد و نظم المعلومات الجغرافية و الجي بي أس و الطائرات بدون طيار
An introduction to database and Geographic Information Systems (GIS) in Arabic
مقدمة في قواعد الب... more An introduction to database and Geographic Information Systems (GIS) in Arabic مقدمة في قواعد البيانات و نظم المعلومات الجغرافية
كتابي السادس عشر في: تطبيقات الفيزياء في علوم الجيوماتكس. ويضم 6 أبواب: الفيزياء و مبادئ الضوء، ق... more كتابي السادس عشر في: تطبيقات الفيزياء في علوم الجيوماتكس. ويضم 6 أبواب: الفيزياء و مبادئ الضوء، قياس المسافات الكترونيا و المحطة الشاملة، تحديد المواقع و الجي بي أس، التصوير الجوى، الاستشعار عن بعد، الجيوديسيا الطبيعية و الجاذبية الأرضية و الجيويد
كتاب يشرح الأجهزة و البرامج المستخدمة في أعمال الهندسة المساحية مثل الميزان و الثيوجليت و المحطة ... more كتاب يشرح الأجهزة و البرامج المستخدمة في أعمال الهندسة المساحية مثل الميزان و الثيوجليت و المحطة الشاملة و الجي بي أس
١٤٣٦ ھـ / ٢٠١٤ م ب ت اﻟﻣرﺟﻊ Shirazian, M. (2013) Quality description in GPS precise poi... more ١٤٣٦ ھـ / ٢٠١٤ م ب ت اﻟﻣرﺟﻊ Shirazian, M. (2013) Quality description in GPS precise point positioning, PhD dissertation, School of architecture and the built environment, Urban planning and environment, Department of geodesy and geoinformatics, KTH (Kungliga
The representation of the Earth' topography in a 3D digital format is a vital constituent in a wi... more The representation of the Earth' topography in a 3D digital format is a vital constituent in a wide range of geographic, geomatics, environmental, and engineering activities. However, the accuracy of such representations could define its applicability and validity for a specific utilization. This chapter presents an analysis of four open-source Global Digital Elevation Models (GDEMs) and compares them on two topographic profiles (nearly flat, and hills regions) for mapping and geomatics applications in two countries. The main goal is to determine whether GDEMs-based heights, contour intervals, slopes, and topographic profiles are accurate for all topographic map scales, which is a significant problem in mapping operations. For the purpose of illustrating flat and moderate-topography patterns, two case studies-the Nile delta in Egypt and Makkah city in Saudi Arabia-have been used. The investigated GDEMs include the most-recent released models: ASTER v.3, ACE 2, SRTMGL1 v. 3, and NASADEM_HGT v.1 released in 2019 and 2020 with spatial resolutions of 1 and 3 arc seconds. There are 540 accurate Ground Control Points (GCP) available in the Nile delta and 175 in Makkah. It has been determined based on the available datasets in two study locations that the accuracy of investigated GDEMs over known checkpoints range from 2.5 and 5.1 meters in the Nile delta region, while it varies between 5.1 and 8.0 meters in the Makkah area. This suggests that the use of GDEMs in topographic mapping varies greatly between spatial areas that are flat and those that are hilly. Therefore, it is advised against utilizing GDEMs to create topographic maps at scales of 1: 25,000 or greater in flat areas and 1: 50,000 or greater in hilly areas. Additionally, the achieved results demonstrated that throughout cross sections up to 30 kilometers in length, no GDEM-based slope matches the real slopes from known GCP. This leads to the conclusion that GDEMs are not the appropriate heights' source for topographic mapping at
شرح مبسط لطلاب المدارس الثانوية للتعرف علي علوم و تقنيات الكارتوجرافيا و الاستشعار عن بعد و نظم ا... more شرح مبسط لطلاب المدارس الثانوية للتعرف علي علوم و تقنيات الكارتوجرافيا و الاستشعار عن بعد و نظم المعلومات الجغرافية و الجي بي أس و الطائرات بدون طيار
An introduction to database and Geographic Information Systems (GIS) in Arabic
مقدمة في قواعد الب... more An introduction to database and Geographic Information Systems (GIS) in Arabic مقدمة في قواعد البيانات و نظم المعلومات الجغرافية
كتابي السادس عشر في: تطبيقات الفيزياء في علوم الجيوماتكس. ويضم 6 أبواب: الفيزياء و مبادئ الضوء، ق... more كتابي السادس عشر في: تطبيقات الفيزياء في علوم الجيوماتكس. ويضم 6 أبواب: الفيزياء و مبادئ الضوء، قياس المسافات الكترونيا و المحطة الشاملة، تحديد المواقع و الجي بي أس، التصوير الجوى، الاستشعار عن بعد، الجيوديسيا الطبيعية و الجاذبية الأرضية و الجيويد
كتاب يشرح الأجهزة و البرامج المستخدمة في أعمال الهندسة المساحية مثل الميزان و الثيوجليت و المحطة ... more كتاب يشرح الأجهزة و البرامج المستخدمة في أعمال الهندسة المساحية مثل الميزان و الثيوجليت و المحطة الشاملة و الجي بي أس
١٤٣٦ ھـ / ٢٠١٤ م ب ت اﻟﻣرﺟﻊ Shirazian, M. (2013) Quality description in GPS precise poi... more ١٤٣٦ ھـ / ٢٠١٤ م ب ت اﻟﻣرﺟﻊ Shirazian, M. (2013) Quality description in GPS precise point positioning, PhD dissertation, School of architecture and the built environment, Urban planning and environment, Department of geodesy and geoinformatics, KTH (Kungliga
Journal of Scientific and Engineering Research, 2023
Vertical land movement is a natural and human hazard that should be precisely monitored. Global N... more Vertical land movement is a natural and human hazard that should be precisely monitored. Global Navigation Satellite Navigation (GNSS), terrestrial levelling, and radar remote sensing provide various technical alternatives to monitor land subsidence. The current research has utilized 23 GNSS stations cover the period 2012-2023 to estimate precise rates of vertical land movements in the Nile delta region, Egypt. The Precise Point Positioning (PPP) approach of GNSS data processing has been utilized. An average accuracy of two millimeters has been accomplished using 24-hours continuous GNSS dataset at each station. The accomplished 3D findings demonstrate that the land vertical movements over the entire Nile delta region vary between-7.2 mm/year and +2.6 mm/year with an average equals-1.4 mm/year. Hence, it is recommended to take into account the influences of such hazardous phenomenon on the huge infrastructures and development plans in the Nile delta region that contains almost half of the population of Egypt.
An optimum Global Geopotential Model (GGM) is required either to represent the long wavelength of... more An optimum Global Geopotential Model (GGM) is required either to represent the long wavelength of the Earth's gravitational field in gravimetric geoid modelling or to act as a stand-alone national geoid in some developing countries. Thus, the current research aims to investigate the performance of seven recent high-order GGMs over Egypt utilizing the most recent precise Global Navigation Satellite Systems(GNSS)/Levelling datasets. Attained results showed that the investigated GGMs perform differently over Egypt with an accuracy level varying between ±0.249 m for the SGG-UGM-1 model and ±0.300 m for the GECO model. Removing outliers in the terrestrial dataset reveal significant improvements, in terms of standard deviations. Consequently, the performance of the investigated GGMs has been modified where the EIGEN-6C4 model became the best model with a standard deviation equals ±0.172 m. Furthermore, a 3D spatial correction surface has been constructed and has been added to the original EIGEN-6C4 model to get an enhanced version of the global EIGEN-6C4. Over checkpoints, the average error of the enhanced model equals −0.018 m with a standard deviation equal ±0.011 m. That means that incorporating terrestrial geodetic data into the global EIGEN-6C4 model has increased its accuracy in Egypt by almost 36 %. Accordingly, such developed enhanced GGM represent the optimum stand-alone geoid model in Egypt. Nevertheless, such accuracy levels of GGMs do not fulfill the requirements of high-accuracy surveying and civil engineering applications. That concludes that a precise national geoid model is still crucial. It is recommended that all available geodetic datasets should be collected from all governmental and private organizations to construct a national geodetic database that would be implemented in modelling an Egyptian local geoid.
Engineering activities and development plans rely chiefly on the availability of precise spatial ... more Engineering activities and development plans rely chiefly on the availability of precise spatial data, which in turn depends the accessibility of an accurate Geodetic Data Infrastructure (GDI) as reference frames for all geospatial measurement GDI is considered a key component in the undergoing National Spatial Data Infrastructure (NSDI) for Egypt. The current study proposes a structure of a GDI in Egypt that has multi database combining several types of geodetic datasets within a Geographic Information Systems (GIS) environment. The study develops such a GDI for the Nile delta region, as a case study, containing the available heterogeneous geodetic datasets. The problems and advantag recommendations are presented, too, for constructing an integrated GDI over a national scale in Egypt.
Egypt is facing several hazardous environmental phenomena, particularly Sea Level Rise (SLR) and ... more Egypt is facing several hazardous environmental phenomena, particularly Sea Level Rise (SLR) and land subsidence. It has been considered to be one of the countries most likely to be affected by SLR because of the low elevation of the Nile Delta region’s northern coastal zone, like all world Deltas. For that, a GIS inundation model has been generated using an original high accuracy local digital elevation model for the Nile Delta region, Egypt (LDEM) and the SLR data measured by the tide-gauges. This model has been used to determine the vulnerable low laying areas to inundation from future SLR in 2050 and to determine land-use types and percentages that are most likely to be affected in the northern Mediterranean coast of Nile Delta region. Finally, a total Hazard Index Map (HIM) has been produced from combining SLR HIM, and the subsidence HIM for the study area which will present the full danger of the two phenomena on the coastal region. The results have shown that the inundated ar...
A high accuracy Digital Elevation Model (DEM) for the Nile delta region, Egypt is needed for seve... more A high accuracy Digital Elevation Model (DEM) for the Nile delta region, Egypt is needed for several environmental applications, particularly for investigating the hazardous impacts of sea level rise and land subsidence phenomena. Since there is no official published national DEM for Egypt, an original high accuracy local digital elevation model (LDEM) for that region has been created using nine Spatial Interpolation Methods (SIMs) within a Geographic Information Systems (GIS) environment. The interpolation process took place after digitizing over than 220 topographic maps of scale 1:25,000, where more than 810,000 elevation (spot heights) points have been extracted from these maps. Multiple parameters and criteria for each SIM were applied to reach the optimal settings to produce a LDEM for environmental applications. The developed LDEMs have been compared against eight free Global Digital Elevation Models (GDEMs) using about 200 known GPS/levelling Ground Control Points (GCPs), wh...
One of the main categories of word is conjunctions which has a much more limited extension in rel... more One of the main categories of word is conjunctions which has a much more limited extension in relation to other categories. Most of Persian language grammarians divide this category into three groups: coordinating conjunctions, prepositions, and marks. The conjunction word "and" is one of the most important coordinating conjunctions in Persian and Arabic Languages that as a joint plays the role of a connection between the components of a sentence, and sometimes between several sentences. The ability of this word in accepting different meanings and functions provides an opportunity for Persian language speakers to enjoy this conjunction in different positions for a better embellishment of their speech and for avoidance of using repeated structures. Saadi Shirazi, who is one of the most fluent and eloquent speakers of Persian language, has enjoyed this potential in Persian language a lot. The authors of this article have attempted to study the extensive functions of this con...
The harmful impact of no-check observations in GPS networks is discussed. The concept of redundan... more The harmful impact of no-check observations in GPS networks is discussed. The concept of redundancy number as an indication of no-check observations is examined. A new method is proposed to detect these observation defects. The suggested algorithm is based on analyzing the leastsquares adjustment results and, therefore, it could be easily included in any least-squares adjustment procedure without additional computations.
This study aims to develop a Local Geoid Model (LGM) for Egypt to determine the optimal combinati... more This study aims to develop a Local Geoid Model (LGM) for Egypt to determine the optimal combinations of global models with Global Navigation Satellite Systems (GNSS/Levelling) data. A precise national geodetic dataset, four Global Geopotential Models (GGMs), and three global Digital Elevation Models (DEMs) have been utilized. Hence, twelve gravimetric LGMs have been developed using the Least-Square Collocation (LSC) method fitted to GNSS/Levelling data and judged over 100 checkpoints. Results revealed that improvements in local geoid accuracy are attributed mainly to GGMs models representing the long wavelength of the Earth's gravitational field. Regarding DEMs, the accuracy of LGMs does not significantly depend on the utilized DEM. Based on the available data, the attained optimum geoid of Egypt has been developed with a standard deviation, equals 0.129 m.
Global Navigation Satellite Systems (GNSS) surveying has been extensively performed for a wide ra... more Global Navigation Satellite Systems (GNSS) surveying has been extensively performed for a wide range of mapping activities. Precise Point Positioning (PPP) is considered a major approach for collecting and processing 3D GNSS data for static and kinematic applications. Processing PPP data results in 3D coordinates based on the most recent International Terrestrial Reference Frame (ITRF) while a national mapping system might be related to another frame. This study aims to investigate several simple ITRF transformation formulas (between ITRF 2014 and ITRF 1994), within the accuracy limits of kinematic surveying, particularly in coastal areas in Egypt. Twelve coordinate transformation methods, in 3D and 2D scenarios, have been analyzed using about two thousands GNSS points along the Red sea coastlines. Accuracy analysis has been performed for each model trying to figure out the optimal approach to be utilized in topographic mapping projects in Egypt. Results showed that almost all model...
This research aims to evaluate the accuracy and reliability of utilizing global Digital Elevation... more This research aims to evaluate the accuracy and reliability of utilizing global Digital Elevation Models (DEMs) in risk monitoring of Sea Level Rise (SLR) in the Nile delta region, Egypt. Such a Geographic Information Systems (GIS)-based assessment process has been carried out using high-precision terrestrial surveys to develop a new local DEM (named SRI18) to precisely identify possible inundated areas by 2025. The presented DEM comparison approach has been performed based on spatial distribution rather than the traditional point-wise method. Based on novel proposed evaluation indicators, it has been found that the reliability of three investigated global models (namely: SRTM1, ASTER, and EarthEnvi-DEM90), in delineating sea level rise flooded areas, is less than 20%. Hence, it is concluded that the utilization of global DEMs may not be optimum in the planning and management of coastal areas in the Nile delta region. Such a methodology could be applied in other low-lying deltaic ar...
Global Digital Elevation Models (DEMs) have been utilized in various geomatics activities worldwi... more Global Digital Elevation Models (DEMs) have been utilized in various geomatics activities worldwide. Recently, there exist several available DEMs vary significantly in terms of spatial resolution and release dates. This paper examines the reliability of eight recent global DEMs, namely the EarthEnv-D90, SRTM 1, SRTM 3, ASTER, GMTED2010, GLOBE, GTOPO30, and AW3D30, in two study areas in Egypt and Saudi Arabia representing different topography patterns. Known ground control points with measured accurate coordinates and precise elevations have been utilized in evaluating the performance of those DEMs. It has been concluded that such a judgment procedure should not be carried based on a single statistical measure. First, five statistical measures, specifically the range, standard deviation, correlation, kurtosis, and skewness, have been evaluated separately for each DEM's errors. Then, a new reliability index is introduced based on the weighted average concept. The accomplished results show that global DEMs perform differently in different topography patterns. It has been concluded that the EarthEnv-D90 and SRTM1 models attain high reliability indexes in the Nile delta region that represents a flat topography, while the GMTED2010 and EarthEnv-DEM90 models came in the first places for the second study area, Makkah, which represents mountainous topography.
On a global scale, the sea level exhibits a relatively rapid rise from 20,000 years ago until pre... more On a global scale, the sea level exhibits a relatively rapid rise from 20,000 years ago until present levels were reached some 4,000 years ago. Since that time, the changes have consisted of oscillations of small amplitude. From a geodetic point of view, the significance of sea level is based on the reality that the Mean Sea Level (MSL) is conventionally taken as the vertical datum of the precise levelling (heights) network. This research study aims to evaluate the variations occurred in MSL over the twentieth century. Long-term tide observations have been collected for two tide gauges at Alexandria, and one tide gauge at Port Said. The obtained results show that the MSL at Alexandria varies from 1.6 cm to 23.5 cm above the current national vertical geodetic datum, with a mean value of 11.1 cm. At Port Said, MSL changes between –1.7 cm to 24.0 cm, with an average of 9.0 cm. Furthermore, it has been concluded that the sea level is rising by a rate of 1.7 mm/year at Alexandria, and 2....
The issue of datum transformation of GPS output coordinates from the global geocentric WGS84 datu... more The issue of datum transformation of GPS output coordinates from the global geocentric WGS84 datum to the local national Egyptian non-geocentric coordinate system is a crucial dilemma in Egypt. Although the traditional similarity datum transformation models have been used for several decades, recent research studies show that this approach may not be the optimum technique to describe the mathematical relationship between geodetic datums. In this paper, the available recent and accurate geodetic databases in Egypt are used to investigate the accuracy of traditional and unconventional approaches of datum transformations. Moreover, the famous models of the traditional similarity datum transformation technique have been examined in several scenarios with different number of unknown parameters. New regression formulas have been developed to transform the GPS coordinates from the global datum to the local one. The obtained results show that the overall accuracy of the traditional transfor...
The integration between both GPS and GIS technologies has proved to be precious in collecting, ma... more The integration between both GPS and GIS technologies has proved to be precious in collecting, managing, analyzing, and presenting spatial data. A problematic aspect of dealing with GPS-based datasets is that their heights are ellipsoidal type in nature, while the traditional height type used in civil engineering and mapping activities is the orthometric height. A height conversion methodology is needed, through the so-called geoid modelling, in GPS/GIS data integration. This paper develops a conversion scheme, within a GIS environment, that transforms ellipsoidal into orthometric heights of collected GPS data survey utilizing the most-recent EGM2008 global geoid model. Results of testing the proposed technique, using 300 ground control stations along the Nile river in Egypt, reveals that the excepted accuracy is less than quarter a meter. Performing the height transformation process inside a GIS environment enables efficient and faster management of GPS data collected for GIS proje...
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مقدمة في قواعد البيانات و نظم المعلومات الجغرافية
مقدمة في قواعد البيانات و نظم المعلومات الجغرافية