ESTIMATION OF BAGHDAD UNIVERSITY REGION EXACT COORDINATES BY USING REMOTE SENSING TECHNIQUES & GIS

In this research exact Coordinate points of Baghdad University locations were estimated by utilizing one of importance Remote Sensing (RS) techniques: Differential-Global-Positioning-System (DGPS) field to measure referencing points, then Inverse-Distance-Weight (IDW) Interpolation of Geographical-Information-System (GIS) was applied to defined each point coordinates in the study regiondepending on DGPS measurments. Eight referencing points were measured in Baghdad University region for having exact coordinates: Longitude, Latitude and DEM. ArcMap-GIS & Excel programs were utilized to determine the results.

Vertical Accuracy of Digital Elevation Models Based on Differential Global Positioning System

The Digital Elevation Model (DEM) has been known as a quantitative description of the surface of the Earth, which provides essential information about the terrain. DEMs are significant information sources for a number of practical applications that need surface elevation data. The open-source DEM datasets, such as the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER), the Shuttle Radar Topography Mission (SRTM), and the Advanced Land Observing Satellite (ALOS) usually have approximately low accuracy and coarser resolution. The errors in many datasets of DEMs have already been generally examined for their importance, where their quality could be affected within different aspects, including the types of sensors, algorithms, terrain types, and other features. Ground control points (GCPs) used in this study were observed through the utilization of differential global positioning system (DGPS) with dual frequencies. Statistical indices were used to compare, evaluate, and validate the DEMs data against DGPS data. Statistical analysis of DEMs pointed out that SRTM accuracy was higher, with Root Mean Square Error (RMSE) of ±6.276m as compared to the other DEMs. ASTER showed the biggest residual error with an RMSE of ±10.241m. Nevertheless, ALOS was noticeably improved by having an RMSE of ±6.988m.

COMPARISON THE ACCURACY OF COMPUTING POINT COORDINATS BETWEEN DIFFERENT INSTRUMENTS AND APPLICATIONS OF GPS

The study was aimed to determine the coordinates of the points were measured by different ways and different instruments, the most precise way using the differential global positioning system (DGPS) that will be the reference measurements in comparison, less precise way using navigator GPS. Google earth (pro.), and the other applications of GPS mobile ( Samsung and I-phone). In this research (8 points) were chosen that are occasional in location. The comparison of the different observations can give us an idea of ​​the extent to which the accuracy of the observations differs from the different devices used in the observing, as well as through the knowledge of the best device and the best way to measure coordinates accurately to serve the desired purpose.

Uso de imagens do projeto PE3D para nivelamento de poços a serem usados em confecção de mapas potenciométricos

Para confecção de mapas potenciométricos é necessário dispor das cotas do terreno a fim de obter o valor das cargas hidráulicas, porém, a obtenção dessas cotas por meio de levantamentos topográficos nem sempre é tão rápida e fácil. O uso de imagens de satélite para esse fim é frequente. O objetivo desse trabalho é avaliar a efetividade do uso de imagens do projeto Pernambuco Tridimensional (PE3D) para construção de mapas potenciométricos. O projeto PE3D trata-se de um recobrimento aerofotogramétrico de todo o estado de Pernambuco com alta precisão. Para atestar esse propósito foram feitos levantamentos topográficos utilizando o Differential Global Positioning System (DGPS), que fornece precisão até milimétrica. Esses levantamentos foram feitos em duas áreas diferentes, uma delas localizada na Bacia Sedimentar de Carnaubeira da Penha (PE) e outra na Bacia Sedimentar de Cedro (PE), somando 32 pontos. A partir desse levantamento as maiores diferenças entre as cotas obtidas por meio do DGPS e as cotas obtidas pelas imagens do PE3D, em termos absolutos, foi de 0,625 m, enquanto a menor diferença foi 0,007 m, sendo então a média 0,211 m. Também foram comparados os resultados do GPS de navegação, pois as coordenadas (X,Y) utilizadas no caso anterior foram adquiridas pelo DGPS, e este não é utilizado nos trabalhos de campo habituais. A maior diferença entre as coordenadas obtidas pelo GPS comum e o DGPS foi de 4,724 m, enquanto a menor diferença foi de 0,246 m, sendo então a média 1,780 m. Essas diferenças, portanto, não são suficientes para que a cota obtida pelo GPS comum apresente erros que mudem a forma do mapa potenciométrico. Conclui-se também que o uso de imagens do projeto PE3D é recomendado para estudos tanto de caráter regional, quanto para estudos detalhados.

Outdoor Localisation for Navigation Tracking using Differential Global Positioning System Estimation (DGPS) : Positioning Errors Analysis

Global Positioning System (GPS) is a very popular outdoor positioning system. Due to the satellites’ errors signal, the Global Positioning System (GPS) receivers determine the accuracy of a current location with about 100 meters in latitude and 156 meters in longitude. In this few years, the technology on autonomous vehicles is rising. Autonomous vehicles need to navigate with high positioning accuracy for preventing any potential danger to road user. So in this paper, Differential Global Positioning System (DGPS) experiment will be introduced for improve the positioning accuracy. Differential Global Positioning System (DGPS) operations compose of Reference Station and Rover Station. Both of the station will use the GPS receiver for receiving the positioning data from GPS satellites and the positioning data collected from Reference Station will be used to calculate the positioning errors and the errors correction will then be transferred to Rover Station to improve the positioning accuracy. The results obtained will be discussed based on the average and range of errors in both latitude and longitude, number of satellites detected, Horizontal Dilution of Precision (HDOP), Vertical Dilution of Precision (VDOP) and the improvement on Differential Global Positioning System (DGPS) at the same time in different day. In four days’ results, it can be seen that the number of satellites detected will be affected by the Horizontal Dilution of Precision (HDOP) and Vertical Dilution of Precision (VDOP) which cause the positioning errors in latitude and longtitude. The average of positioning errors range between -4.165m and 2.925m in latitude and -0.618m and 1.998m in longitude.