Development of a web based GIS inventory to visualize the location and current status of geodetic control points
Abstract
Description cards are detailed paper forms used by land surveyors to obtain geodetic control information, and are usually obtained from the Department of Surveys and Mapping in Entebbe. They are hard to navigate by, especially in the central region because site descriptions have become outdated due to the rapid urbanization. In Uganda, many of the control points have been damaged or vandalized, but there is little or close to no information published about it. The main objective of this project was the development of a web-based GIS inventory to visualize the location of geodetic survey controls along with their up-to-date working status, and also provides for addition of new geodetic control points. Description cards for the control points, these were then transformed from Arc 1960/ UTM 36N to WGS84/ UTM 36N (Eastings, Northings), then after converted to geographic coordinates (Latitude, Longitude,). Using PostgreSQL, this data was entered and a spatial database created from the entries. The system requirements were assessed and using VScode, the coordinate transformation function and the web application were programmed in python language using Flask framework. The Hypertext Markup Language (HTML) was the language used for creating web pages, with Cascading Style Sheets (CSS) and JavaScript, the web application was compiled together. The database was then uploaded onto the system and hosted on a local server. The system was then fully tested and debugged. The application performs the following functions such as; Creation of new control points by users and there after submitting them for validation; Coordinate transformation from Arc 1960/ UTM 36N to WGS84/ UTM 36N; Searching control points by Point ID, or by location; Adding user reviews for a given control; Visualization of control points and their current working condition. Using questionnaires, a number of users (field surveyors) were interviewed and the answered results were analyzed and recommendations made accordingly. The main recommendation made was to add a Uganda Gravimetric Geoid (UGG2014) model to the system that can compute orthometric heights for a given new survey control added.