Shapefiles and Geometric Analysis in GIS Projects

What is a Shapefile?

A shapefile is an Esri vector data storage format for storing the location, shape, and attributes of geographic features. It is stored as a set of related files and contains one feature class. Google Earth, an Online Satellite Imagery (OSI) Technique, is a tool for generating shapefiles.

Geometric Analysis Tools in Projects

Example 1: Population Maps of To Kwa Wan using ArcGIS

We used ArcGIS to create population maps of To Kwa Wan.

1. Selected population and working population data from the C&SD department.
2. Opened TPUs with the population data in ArcGIS.
3. Calculated the area of the TPUs based on Hong Kong 1980 Grid, determining population densities.
4. Created maps with different population densities, using graduated colors to represent different densities.
5. Exported the maps.

It was convenient to calculate the population densities of the TPUs, and ArcGIS was useful for generating maps with different population densities.

Example 2: Catchment Area Analysis using Google Earth and QGIS

We used Google Earth and QGIS to find the catchment area of recreational areas and main transport spots, as well as the distances from residential buildings to recreation areas and main transport spots.

1. Used Google Earth to create shapefiles of recreational areas, main transport spots, and residential buildings in To Kwa Wan.
2. Opened the shapefiles and the TPU file in QGIS.
3. Assigned different colors and symbols for different shapefiles for easy recognition.
4. Chose 200m as the buffer distance of recreational areas and 100m as the buffer distance of main transport spots.
5. Dissolved and clipped the buffer.
6. Exported the map of catchment areas.
7. Calculated the size of catchment areas, the number of residential buildings within the catchment areas, and the distances from residential buildings to recreation areas and main transport spots.
8. Selected the shortest distances and shown them in intervals of 100m in bar charts.

It was very tedious and time-consuming to pin the residential buildings as there were about 800 of them. However, seeing the outcome gave us a great sense of accomplishment. Moreover, it was interesting to discover the coverage of the recreational areas and main transport spots by using Google Earth and QGIS.