5/1/2023 0 Comments Igrade pdf![]() ![]() Although it is widely applied in different fields, but it is not widely used in surveying applications. Artificial neural networks appeared as one of the prediction methods used in many disciplines. However some mathematical models are used for condensing spot heights with a relatively low cost. ![]() Leveling procedure can be considered as one of the most costly procedures. Now a day Global Positioning System (GPS) provides a quick modern technology to determine heights of points. Moreover it can be carried out trigonometrically or barometrically. It may be precise when precise optical or digital levels are used, or it may be ordinary when using ordinary optical, automatic or digital levels. Levelling process can be carried out using different survey equipments and techniques. In ordinary orthometric levelling Geoid surface is usually used as a datum. If a datum surface is defined for the observed points, the heights of these points (reduced levels) can be computed. Levelling in surveying is the term stand for height difference determination between ground points. ![]() Moreover, GPS data can be reduced to a new arbitrary datum so that contour maps at scale 1:5,000 and smaller can be plotted. This result leads to ability of GPS to produce grid vector map at scale 1:5,000 and smaller. Therefore, GPS can be used in many engineering applications when variation in height is the main target. Results obtained showed that the accuracy in levelling for GPS data in levelling for height differences is better than the accuracy of orthometric height determination. In this research work, difference in heights between numbers of points, in Khartoum State (Sudan), were carried out using both ordinary orthometric levelling (in which geoid is the reference datum) and GPS techniques (in which ellipsoid is the reference datum). Therefore, different reduced levels can be expected compared with orthometric leveling. But here, the datum surface is already defined with ellipsoidal surface. ![]()
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