Horizontal Accuracy Assessment of Digital Aerial Photograph in Urban Cadaster: The Case of Wereda 10, Gulelie Sub-City, Addis Ababa
No Thumbnail Available
Date
2018-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Positional accuracy deals with the accuracy of the location of map features, and measures how far a spatial feature on a map is from its true or reference location on the ground. This research focused on the following problems: Coordinate shifting, area variation and shape difference between the ground measurement, line maps and digital aerial image. The main objective of this study is to assess the horizontal position accuracy of aerial photogrammetric image generated coordinates of Wereda 10, Gulelie sub city. There are three basic data sources used to assess horizontal accuracy assessment: Such as Geo referenced digital aerial photograph, digital line map and GPS data. This research contains the following steps: First step created twenty sample GCP points by using static GPS. The seconded step is process sample GCP points by using Leica Geo office combined software. While, the third step is measured hundred parcel corners points by using RTK GPS as a reference used the established GCP points. In addition, the fourth step is digitized parcel corner points and polygons from aerial photograph and digital line map. Finally, assessed horizontal accuracy, standard deviation, means value, minimum and maximum values. The paper describes the visualization possibility of estimated results of horizontal positional accuracy of digital aerial photographs and established cheek points and area, side length and coordinates comparison for digital aerial image and digital line map based on RTK GPS. The root mean square error results of twenty check points and digital aerial photograph the easting and northing component is 18.1cm and 18.8cm, respectively. The RTK GPS and aerial image comparison coordinates results show that the root mean square error of easting and northing component is 37.6cm and 38cm respectively. The RTK GPS and digital line map coordinates comparison results show that the root mean square error of easting and northing component is 39.2cm and 39.8cm respectively. The root mean square error is 5.828 m2 and 5.852 m2 in aerial photograph and digital line map respectively. The root mean square error is 38.1cm and 40 cm in aerial photograph and digital line map side lengths respectively. Therefore, these variations come from different factors: Such as shadows, topographic factors, vegetation covers and there are some limitations to these techniques as it solely on visual interpretation.
Description
Keywords
GPS, RTKGPS, RMSE, Digital aerial image, Digital line map