Import satellite raster
With the help of satellite images it is possible to track the growth rate of the biomass on the field. In this tutorial the EO-Browser is used to download different raster band from European satellite images. (If you know other sources of free satellite images let me know and I add a link to them here.)
Download data from the EO-Browser
Go to the EO-Browser
in order to download satellite data.
You need to click on sign up and register in order to download images from the EO-Browser. When you have completed your register, confirmed your e-mail and logged in you are able to download the images.
Make sure that Sentinel-2 is selected and one of (or both) L1C and L2A is selected (I'll update this later when I've understood which one is the best for biomass index analysis). I would also recommend lowering the max percentage of clouds to say 20% in order to filter out days with a lot of cloud cover. Before you hit search you also need to update the dates where you want to find raster images. Then this dialog shows which days where there are satellite images (minus those remove by the cloud filter):
When you have selected one of the days (press "Visualize") you can browse through the data with these arrows
. When you have found the date you want to base you guide file on press on (1.) in the picture bellow:
- Press to open the download dialog.
- Select Analytical in order to download specific bands of the satellite image.
- Change to Tiff.
- Download the high resolution image.
- Change the coordinate system to WGS84 (EPSG: 4326)
- Select the raster band 4 (B04) and 8 (B08).
- Press download will now download a zip file.
Now open QGIS and the GeoDataFarm plugin and go to the "EU satellite tab" and you will se the following view:
- Press to load your fields in the dropdown menu to the side.
- Select the field you want to create.
- Select the index method, there are several different indexes that calculates the biomass. The absolute values will differ but the relative difference between these two methods are similar (don't hesitate to give me feedback on this).
- Select the zip file that you have downloaded.
- After some time this list will be updated, where the first value is the % of the index, the interval is linked to the areal with that index.
In this case have 0.64ha of the field an index between 31% and 43%, 0.55ha has an index in-between 43% and 54%, and so on.
- Here you have to decide how much fertilizer that you want to apply with regards to the difference in biomass index.
- Press here to update the graph after you have changed applications.
- On the x-axis is the % of index and on the y-axis is the application yield.
- Click this button if you want add the data directly to your farm database (otherwise you have import the shape file later in order to analyse it).
- If you have checked the button on top you can select a planned date of application.
- Press here to generate a guide file (and if the checkbox is selected add the data to database).