Friday, June 24, 2016

How to Extract a GIS Dataset Selection into a New Dataset Layer Using QGIS

In this post, am going to talk about How to Extract a GIS Dataset Selection into a New Dataset Layer Using QGIS.

Often you will find yourself working with a large geographic dataset in QGIS and you want to select a smaller geographic section and convert it to a new file.

Consider a situation whereby you have a large dataset and you needed a new dataset out of the exsisting one to form a new dataset layer.

Here is what I mean in another word, lets say you need to have a new dataset layer of just the states in Southern part of Nigeria? Since you have a dataset layer containing all the states in the country, how would you extract out just the states in Southern part?

This is how it is done in QGIS.

~ Load your Dataset layer (Nigerain_states.shp) shapefile

~ Go to "View" menu >> Select >> Select features by Polygon

~ Draw a polygon around the states in Southern part to select them

~ Export the Geography Selection to a New GIS Dataset by right-clicking on the layer in the layer panel and select “Save As..”
~ The window that pops up provides several options to choose. 
1- Under "Format select the file format (shapefile, GeoJSON, KML, etc.) you want to export the geographic data as.
2- Next, in the "Save as" section click on the Browse button to select the file directory to save the data to in the window that pops up. This is also where you will type in the file name that you want the GIS data to be saved as. 
3- Finally, in the "Encoding" section, make sure the “save only selected features” option is checked.  You can optionally set other parameters in this section if desired.  If you want to load the new layer into your legends window, make sure the box for “add saved file to map” is checked (typically this is already on by default).

~ Click on OK and your new file will be save to the designated directory and added to your open QGIS file.

That is it. Hope you understood the process? Feel free to drop your comment or questions if you have any.

Thanks for reading

No comments:

Post a Comment