Many times the GIS data comes in a table or an Excel spreadsheet. If you have a list of lat/long coordinates and some attributes, you can easily use this data in your GIS project. In this tutorial, I will show you how to import and use such tabular data into Quantum GIS. We will using a plugin called ‘Add Delimited Text Layer’ for this.
The dataset we will use comes from NOAA’s National Geophysical Data Center. We will be importing the Significant Earthquake Database containing information about all major earthquakes globally.
The dataset we will use comes from NOAA’s National Geophysical Data Center. We will be importing the Significant Earthquake Database containing information about all major earthquakes globally.
- Examine your tabular data source. To import this data to QGIS, you will have to save it as a text file and need at least 2 columns which contain the X and Y coordinates. If you have a spreadsheet, use ‘Save As’ function in your program to save it as a ‘Tab Delimited File’ or a ‘Comma Separated Values (CSV)’ file. Once you have the data exported this way, you can open it in a text editor such as Notepad to view the contents. In case of the Significant Earthquake Database, the data already comes as a text file which contains latitude and longitude of the earthquake centers along with other related attributes. You will see that each field is separated by a TAB.
- In Quantum GIS, enable the ‘Add Delimited Text Layer’ plugin. In you don’t have it, refer to this tutorial on finding and adding plugins.
- Once enabled, you will see a menu item under Layers → Add Delimited Text Layer. Click on it to open the plugin.
- In the dialog box, click on Browse and specify the path to the text file. Then in the delimiters section, check the ‘Tab’ delimiter. If your data is in CSV format, you should check the ‘comma’ as the delimiter. The plugin will try to guess the correct X and Y coordinate fields. In our case they are LONGITUDE and LATITUDE. You may change it if the plugin selects the wrong fields. Click OK.
- In the next screen, you will be asked to select the Coordinate Reference System. Since the earthquake coordinates are in WGS84, we select that. Click OK.
- You will now see that the data will be imported and displayed in the QGIS canvas. The layer is now imported and ready for analysis. You may right click on the layer and select ‘Save As’ to save it as a shapefile. This way you can readily use it again without importing.
