Digital Geography

24. March 2015

Landsat in Love with QGIS: the newest coup from Luca

The normal way of getting Landsat data for your GIS projects often was: visit a Landsat data mart like landcover.org, earthexplorer or WIST, search for your area and time and download/order your desired data. Once you’ve done this, you were prepared to add, analyse and publish this data/results with QGIS. Luca Congedo from the blog “From GIS to Remote Sensing” .

The Plugin SCP

Luca developed a plugin called Semi-Automatic Classification Plugin or in short SCP:
The Semi-Automatic Classification Plugin (SCP) is a free open source plugin for QGIS that allows for the semi-automatic classification (also supervised classification) of remote sensing images. Also, it provides several tools for the pre processing of images, the post processing of classifications, and the raster calculation.
Once a domain of ERDAS, Matlab, R and other more numeric orientated software packages, SCP makes it possible to extract vector data from raster images in a convenient way:   You can download it via the plugin handler in QGIS.

Landsat and QGIS

In the newest version it uses the latest developments of Amazon which now offers Landsat data via direct access. Once installed, you can search, display and download Landsat 8 images via the SCP plugin directly in QGIS…

The main plugin window: SCP

The plugin has two main windows:
  1. SCP: Classification – Here you can do your fancy classification steps and also download of data.
  2. SCP: ROI creation – Here you define your Region of Interest.
Once you choose to “Import […] USGS spectral library” a new window comes up with several tabs. One of them is called “Download Landsat 8”:

Landsat 8 downloader with filled corner coordinates

You just need to define the upper left and lower right corner coordinates by typing or interactive selecting via the cursor tool, select the required maximum cloud coverage as well as the temporal coverage and press the “find images” button to get a list of appropriate scenes. There is also the possibility to add the previews to your current project which is a nice way to get an idea about scenes: a 80% cloud coverage is not so bad if your ROI falls in the remaining 20% …

Landsat preview in QGIS

Once you’ve found a good scene, you can download it directly into your working folder:

folder with downloaded images

Summary

The newest version of the SCP plugin provides a great interactive way to browse and download Landsat 8 date for your specific area of interest. It has the advantage of offering all scenes instead of only selected snapshots as in other online services without any authentication or affiliation. Unfortunately the progress bar for downloading images was not working in my example and I got always 0% till finishing the job. Especially for Landsat 8 it could be a good thing to have, keeping in mind that one scene has 740mb  of data…

Further Information

Luca created a short “Tutorial” on this feature as a video. Enjoy it: