Landscape Modeling with the Use of Ground Surveying Spot Elevation Measurements at Bare Lands

摘要

Landscape modeling is considered as a main objective of any terrain investigation operation that is usually performed through qualitative and quantitative analysis of the earth's surface. Quantitative studies of the terrain landscape demands acquisition of extensive high-resolution topographic data for the extraction of the earth's surface parameters and the landscape components through exploitation of the main products of the topographic data namely; the Digital Elevation Models (DEMs) as inputs. Engineering surveying methods can provide high quality digital elevation measurements that can be utilized in the creation of the DEMs necessary for landscape modeling processes. Different factors such as; the data source, the original point data density, the spatial resolution and interpolation scheme determines the quality of the generated DEM which intern affects the process of the landscape modeling. This research is focused towards investigating the effects of the spatial resolution on the quality of the DEM as a main input in landscape modeling operations. Real elevation measurements collected from a test site close to Cairo, Egypt have been used in creation of DEMs with varying resolutions. Qualitative and quantitative analysis have been applied on that DEMs through the application of 3D visual analysis, the statistical analysis of residual DEMs, analysis of contour-line maps generated from the residual DEMs, profiling at mild terrain landscapes and finally profiling at rough terrain landscapes. The analysis has shown decrease in terrain corrugations and landscape details with the decrease in grid resolution. In addition, coarser tone and coarser texture 3D views have been obtained from lower resolution DEMs. The statistical analysis of the residual DEMs has indicated decrease in the ranges of elevation residuals and increase in the mean standard errors of the residual DEMs due to degradations of the DEM resolution. Analysis of the residual contour-line maps generated from the residual DEMs has shown decreases in the residual contour-line concentrations with the decrease in the DEM resolutions. Additionally, there has been increasing deterioration in the extracted profiles with increasing the size of the grid cells which makes the profiles to be increasingly stepped. Moreover, degradations in the DEM grid resolution have produced bigger deteriorations of the extracted profiles at rough terrain landscapes than that at mild terrain landscapes.