Browsing by Author "Melese Wondatir"

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    Accuracy Assessment of Geospatial Data for Cadastral Application: A Case of Addis Ababa City, Ethiopia
    (Addis Ababa University, 2022-07) Melese Wondatir; Getachew, Tesfaye (PhD)
    Datum transformation is the transformation of coordinate points from one known coordinate reference system into another. The recent practice of geospatial data collection, management, and analysis in Ethiopia is in geocentric coordinates of a point defined based on a global datum (WGS84). However, Ethiopia uses Adindan as the recognized local datum. The current official transformation parameters in use by Ethiopia are slightly different from the parameters determined by previous research and adopted in widely used geospatial software packages. In addition to this, the rotation and scale changes are ignored in the transformation parameters. The current practice of cadaster in Addis Ababa city is below the accuracy level of all local and global geospatial data standard guidelines. The main purpose of this study is to assess and evaluate the Accuracy Assessment of Geospatial Data for Cadastral Application: A Case of Addis Ababa City, Ethiopia. Statistical analyses have been done for second-order GCP, orthophoto, and cadastral parcel accuracy assessment analysis based on ASPRS 2014 standards. The positional accuracy of second-order ground control points, orthophoto, and cadastral parcels evaluated by checkpoints is determined as 0.47m, 1.326m, and 1.87m respectively at a 95 % confidence level. Finally, the software packages used to convert from global to local reference datum differ from one another, causing major changes in the values of specific points. Coordinates values of Orthophoto and static GCPs were converted from WGS84 to Adindan using (X = 162m, Y = 12m, and Z = -206m); the RMS error of easting and northing values were 0.32 m and 0.69 m respectively. On the other hand, the static GCPs coordinates were converted by using (X = 165 m, Y =11 m, and Z = -206 m) and compared with orthophoto coordinates, the RMS error of easting and northing values were 2.65 m and 0.78 m respectively. And, according to Molodensky-Badekas seven transformation parameters using (169.674 m in X, 14.801m in y, and -204.841 in Z), the RMS error of easting and northing values were 3.055m and 0.697 m respectively. Finally, the researcher recommends these parameters shall utilize as unique and constant values to improve data integrity for geospatial work such as cadastral application.