Geodesy and Geomatics

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Browsing Geodesy and Geomatics by Author "Andenet, Ashagrie (PhD)"

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    Accuracy Assessment of Digital Surface Model from Aerial Images: Case Study of Nifas Silk Sub City, Addis Ababa
    (Addis Ababa University, 2022-03) Jemal, Endrie; Andenet, Ashagrie (PhD)
    Airborne aerial photograph is one of the most effective means of terrain data collection. The vertical accuracy of DSM derived from 2010 and 2016 collected aerial photograph in urban area of Nifas Silk sub city is the critical point in this research. In this study, the reference level produced from GPS elevation, existed GCP elevation and differential leveling are measured to assessed the vertical accuracy of existed GCP elevation and both DSM elevation data derived from Airborne aerial photograph for building urban land cover types. Using static GPS elevation as a reference, the accuracy of existed GCP elevation gave a RMSE value of 1.049m and an arithmetic mean value of 1.049m. GPS reference elevations gave us the RMSE value of 0.592m and 0.787m and an Arithmetic Mean value of 0.466 and 0.659 for used DSM derived from 2010 and 2016 aerial photograph respectively. On the other hand, by using GCP as reference elevation, gave the RMSE value of 0.415m and 0.486m and also used differential leveling elevation, gave the RMSE value of 0.68m and 0.911m for used both DSM derived from2010 and 2016 aerial photograph respectively. A spatial analysis tools can be used for the extraction of DSM elevation in arc GIS software package. Finally, 1.96xRMSE and frequency histogram statistical measurements of data analysis are performed for the difference between measured independent checkpoints and corresponding point of both DSM derived from the two aerial photographs. For our study area, using the three reference elevation point of existing GCP, RTK GPS and Leveling measurements, DSM derived from (2010) aerial photograph elevation data have an accurate by A RMSE value of ±0.071m, ±0.198m and ±0.231m and/or Absolute Mean value of ±0.071m, ±0.198m and ±0.379m that of the value of DSM derived from (2016) aerial photograph data respectively.