Geometry Data Extraction System
The front-end functional capability enables user to type in location and search it, view the searching result, select a bound box and filter the column of exported data. The system uses osm2pgsql tool, and POSTGIS API to get access to the geometry data stored PostgreSQL database from server. The query results will be formatted to.XML, .CSV or .JSON according to user’s requirements.
The system also solves a problem of converting Mercator projection to Latitude and Longitude coordinate. I figure out the difference between PostgreSQL and other object-relational database, how POI data is stored in the database, how to increase the system effectiveness, robustness, efficiency and how to improve the user experience.
Here is the source code on github.
User click “select area” button to choose an area defined by a bounding box. Exported geometry data will be those POI data in the chosen box area.
Then user choose the source table, file format and column to format and polish the table. In some cases, they don’t need all the data in one selected area. For example, it’s likely that someone just interested in highway data near a selected area. The system help him to prune those “useless” before downloading, sparing the band width and storage.
Below are the exporting data, in JSON, CSV or XML format.