DESIGN PRINCIPLES FOR LOW DISTORTION MAP PROJECTION OVER A PROJECT

Abstract

This research has defined the principles of design for Low Distortion Map Projection (LDP) for construction project and developed computer software aided map projection design. Designer could define map projection parameters by specify popular PROJ string format. A software system “LDP_Colab” under Google Colab has been developed for any users can immediately use without installation. The software reads user-defined corridors, produces sampling points within the area and visualizes map results. The LDP_Colab reads orthometric height from SRTM15+V2.1 dataset together with the Earth Gravitation Model 2008 (EGM2008) and produces height scale factor (HSF). According to map projection definitions, software calculates point scale factor (PSF) and then combined scale factor (CSF) over the study area. These CSF values should be within threshold of negligible ±20 ppm. The result CSF for each LDPs will reflect the efficiency for further deployment in the surveying, design and construct works. The research has also analyzed how to optimally apply LDP with traditional UTM map projection in the project. The designated LDP definitions and calculated grid coordinates have been validated with other GIS software e.g., GeographicLib and Global Mapper to ensure numerical accuracy and map projection compatibility.