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Extracting Implicit Feedback from Users’ GPS Tracks Dataset
Published in Ibrahiem M. M. El Emary, Anna Brzozowska, Shaping the Future of ICT, 2017
Tawfiq A. Alasadi, Wadhah R. Baiee
Coordinate systems are location-based reference systems for spatial data on the Earth. Whereas GIS work with geospatial information, the coordinate system acts as the main key in the projects of GIS. Coordinate systems have two main types: geographic and projected. A geographic coordinate system enables every position on the studied area to be stated in three coordinates, using mostly a spherical coordinate system. The projected coordinate system is based on a map projection. For example, the coordinate system of Universal Transverse Mercator (UTM) is built on Transverse Mercator projection.
Cluster analysis of the spatial distribution of pedestrian deaths and injuries by parishes in Kampala city, Uganda
Published in International Journal of Injury Control and Safety Promotion, 2023
Esther Bayiga Zziwa, Milton Mutto, David Guwatudde
Pedestrian crash data was downloaded online from the Kobo Collect mobile devices as an Excel file which was then exported to STATA SE version 14 software (Stata, 2015). For spatial mapping, shape files for parishes in Uganda were obtained from the Uganda Bureau of Statistics (Uganda Bureau of Statistics, 2014). The digital parishes of Uganda in a projected coordinate system Arc 1960 Zone 36 North were imported in the data view of the ArcMap, a Geographic Information System analysis software. In ArcMap, Kampala parishes were selected using the selection by attribute tool and then exported to a storage location as a shapefile which was used for further analysis. Before the analysis, a merge was performed to combine the excel file containing the number of serious and fatal pedestrian crashes with the Kampala parishes using the parish name as the join field.
Traffic state classification and prediction based on trajectory data
Published in Journal of Intelligent Transportation Systems, 2021
Yu Yuan, Wenbo Zhang, Xun Yang, Yang Liu, Zhiyuan Liu, Wei Wang
The aggregation can be completed in two separate steps:Convert the original coordinates based on the geographic coordinate system into a projected coordinate system;Convert the coordinates of trajectory point i, into grid coordinates: according to Equation (1) and Equation (2). where and denote the projection coordinates of the trajectory points; and represent the y coordinate of the north boundary of the study area and the x coordinate of the west boundary respectively; represents the side length of each grid. The size of the grid is chosen based on mainly two criteria: 1) different roads should lies in different grids, so size of spatial grid need to be close to the size of an intersection, while the normal size of a two way intersection is 40 to 60 meters (data got by measuring the size using map services); 2) the number of vehicles in the grids should be adequate for analysis (10 to 15 is enough for estimation the population)；3）to satisfy the need of refined management and real time traffic control, the size of spatial grid and time grid should be small while satisfying the second criteria. In this study, is set to 50 meters, details will be introduced in the case study. Figure 2 shows the mechanism of generating spatial grids, where sequence of exact coordinates is converted to sequence of grids.