Hi folks So we ended the last tutorial video by downloading a tile of Sentinel 2 satellite imagery from the Copernicus open access hub. So this time we're going to begin by going and unzipping the download file, by double clicking on it (for this you may need to install a program like '7-Zip' or 'Winzip', for example) This may take some time when the zip program has opened the file, we can then click copy and choose a place on our computer to save the file. In this case, I am going to go to my QGIS folder and to a folder called 'Sentinel 2'. Click 'OK' and then 'OK' and then we get this progress bar as the compressed file is unpacked. Okay now we are going to go to QGIS. For this, you will need to have the 'Semi-automatic classification plug-in' already installed, which you can see here in this dock and you get this menu for the 'SCP' for 'semi-automatic classification plug-in' up here. Okay, but first we're going to import the images, which are raster files. So we are going to click this 'add raster layer' button. We are going to navigate to the Sentinel 2 folder where we just copied the imagery. We are going to open up the folder... ...go to the 'GRANULE' folder, open that up and then also the folder named image data (IMG_DATA) and then we can see the various bands of data that we have got from the Sentinel 2 image. Highlight (select) those and click open. Ok, then we can see those individual band rasters have appeared in our layers panel. And in order to stack those bands together, so we can see different representations of the earth's surface, we are going to click this 'band set' option, we are going to select all of the bands. There should be 13 of these that come with the Sentinel 2 imagery and we're going to click this plus button to load them... ...into the band set definition window. I am going to click this 'ABC' button to order them by... ...their name. So we get one to twelve and then the thirteenth band is '8a'. Okay, and then I am going click the 'create raster band set' Checkbox there, and then we click this 'Run' button (in the bottom right). Then it asks us for somewhere to save that. So I will go into the Sentinal 2 folder. And I've got a folder called 'band set', where we will save this file. Select folder, and then it will calculate stacking the bands. Okay, so I'm going to minimize the band set window then, Okay, and then while the band set is reduced, I'm going to just go click on this eye symbol, and hide all layers. Turn on our borders of Tunisia, and the band set, and we can see in this window here that when we have the bands 4, 3, and 2 selected, we will see something which is close to natural colours. But if we look at this, little help file that I've got here, we can see that there are various combinations of bands that you can use with the Sentinal 2 imagery if we want to see vegetation we can use bands 11, 8 and 4 for example. So if I go into the RGB Type 11-8-4 and then enter we will see then that the areas of cultivation where we have vegetation showing up show up very nicely in green. Another example would be the false colour urban. So bands 12, 11 and 4 together. And then we can see that the urban areas, Tunis here and various smaller settlements in the region of Cap Bon, show up very clearly in a lilac color when we use that combination of bands. Okay, thanks for listening!
