Accuracy Assessment Of Digital Surface Model From Aerial Images Case Study Of Nifas Silk Sub City Addis Ababa

Airborne aerial photograph is one of the most effective means of terrain data collection. Thernvertical accuracy of DSM derived from 2010 and 2016 collected aerial photograph in urban arearnof Nifas Silk sub city is the critical point in this research. In this study, the reference levelrnproduced from GPS elevation, existed GCP elevation and differential leveling are measured tornassessed the vertical accuracy of existed GCP elevation and both DSM elevation data derivedrnfrom Airborne aerial photograph for building urban land cover types. Using static GPS elevationrnas a reference, the accuracy of existed GCP elevation gave a RMSE value of 1.049m and anrnarithmetic mean value of 1.049m. GPS reference elevations gave us the RMSE value ofrn 0.592m and 0.787m and an Arithmetic Mean value of 0.466 and 0.659 for used DSMrnderived from 2010 and 2016 aerial photograph respectively. On the other hand, by using GCP asrnreference elevation, gave the RMSE value of 0.415m and 0.486m and also used differentialrnleveling elevation, gave the RMSE value of 0.68m and 0.911m for used both DSM derivedrnfrom2010 and 2016 aerial photograph respectively. A spatial analysis tools can be used for thernextraction of DSM elevation in arc GIS software package. Finally, 1.96xRMSE and frequencyrnhistogram statistical measurements of data analysis are performed for the difference betweenrnmeasured independent checkpoints and corresponding point of both DSM derived from the twornaerial photographs. For our study area, using the three reference elevation point of existing GCP,rnRTK GPS and Leveling measurements, DSM derived from (2010) aerial photograph elevationrndata have an accurate by A RMSE value of ±0.071m, ±0.198m and ±0.231m and/or AbsoluternMean value of ±0.071m, ±0.198m and ±0.379m that of the value of DSM derived from (2016)rnaerial photograph data respectively.

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