Effect of Terrain Configuration on the Performance of SRTMv3 and ALOS PALSAR DEMs Over the Federal Capital Territory (FCT), Nigeria.

Charity Michael Olla ,J I Igbokwe ,J C Ojiako ,E C Igbokwe

doi:10.7176/jees/10-6-14

Abstract

Digital Elevation Model (DEM) and its resulting parameters are essential terrain related information. DEM and the extracted information (slope, aspect, roughness etc.) have been identified as one of the most important and fundamental variables to various streams of engineering and planning designs which are the hall marks of development all over the world. Thus, to delineate the major surface and subsurface structures for evaluating the Planning framework for the Federal Capital City of Nigeria, analyzing the effects of terrain configuration of Shuttle Radar Topographic Mission (SRTMV3) and ALOS PALSAR DEM data is very crucial. Hence this paper aimed at examining the effects of terrain configuration of Shuttle Radar Topographic Mission (SRTMV3) and ALOS PALSAR DEM. The methodology involved data acquisition of ALOS PALSAR, SRTMV3 and Ortho DEMs, after which the ALOS PALSAR and SRTMV3 DEMs were resampled to 10m of the Ortho DEM, image classification and then an assessment of the impact of terrain configuration on DEM performance with horizontal profiles was carried out. The results revealed that SRTMV3 v3 performed better with close resemblance with the Ortho DEM on flat and undulating terrain while it underestimated the rolling terrain and overestimated the hilly and mountainous terrain. ALOS PALSAR DEM when compared against the Ortho DEM grossly overestimated all the terrain configuration in the study area. In all, the overall performance of SRTMV3 v3 had a close resemblance in performance to that of the Ortho DEM, while ALOS PALSAR had a significant difference in performance. It was therefore recommended that SRTMV3 v3 should be used as an alternative DEM source where high-resolution elevation data are not readily available. Keywords: ALOS PALSAR, Digital Elevation Model, SRTM, Terrain modelling. DOI: 10.7176/JEES/10-6-14 Publication date: June 30 th 2020

Highlights

From time past, the major source of elevation data has been the traditional ground survey and photogrammetric methods
The Ortho Digital Elevation Model (DEM) was obtained as a result of the aerial survey carried out over Abuja, FCT and has a resolution of 10m. which makes it better than SRTMv3 and ALOS PALSAR in terms of resolution and accuracy
But in order to use the ortho DEM in validation of SRTMV3 and ALOS PALSAR over FCT, the ortho DEM had to be validated first using ground control points on ground, the elevation points obtained from the Ortho DEM was compared with the elevation points pick from ground, the results are illustrated in figure 3.1

Summary

Introduction

The major source of elevation data has been the traditional ground survey and photogrammetric methods. It became necessary to source for economically pragmatic alternative means of generating elevational information; and expedient to use one of freest alternative source of obtaining elevation data for topographic mapping of urban and rural areas for various applications. This is because where local topographical data is unavailable, incomplete or outdated, DEMs from remotely sensed data such as SRTM and ALOS PALSAR GDEM can be the main source of information (Nwilo, 2012). It is important to validate the resulting dataset from the SRTM and ALOS PALSAR DEM because global datasets are subject to errors due to the approach used to extract the elevation information and the processing procedures such as interpolation adopted (Nikolakopoulos, Kamaratakis & Chrysoulakis, 2006)

Objectives

Methods

Results

Conclusion