Samavati, Faramarz FamilStefanakis, EmmanuelKazemi, Meysam2023-09-282023-09-282023-09-20Kazemi, M. (2023). Efficient calculation of distance transform on Discrete Global Grid Systems and its application in automatic soil sampling site selection (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/117163Geospatial data analysis often requires the computing of a distance transform (DT) for a given vector feature. For instance, in wildfire management, it is helpful to find the distance of all points in an area from the wildfire’s boundary. Computing a distance transform on traditional Geographic Information Systems (GIS) is usually adopted from image processing methods, albeit prone to distortion resulting from flat maps. Discrete Global Grid Systems (DGGS) are relatively new low-distortion globe-based GIS that discretize the Earth into highly regular cells using multiresolution grids. In this thesis, we introduce an efficient DT algorithm for DGGS. Our novel algorithm heavily exploits the hierarchy of a DGGS and its mathematical properties and applies to many different DGGSs. We evaluate our method by comparing its distortion with the DT methods used in traditional GIS and its speed with the application of general 3D mesh DT algorithms on the DGGS grid. We demonstrate that our method is efficient and has lower distortion. To evaluate our DT algorithm further, we have used a real-world case study of selecting soil test points within agricultural fields. Multiple criteria including the distance of soil test points to different features should be considered to select representative points in a field. We show that DT can help to automate the process of selecting test points, by allowing us to efficiently calculate objectives for a representative test point. DT also allows for efficient calculation of buffers from certain features such as farm headlands and underground pipelines, to avoid certain regions when selecting the test points.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Distance TransformDiscrete Global Grid SystemsGeographical Information SystemsComputer Sciencemaster thesis