We are continuing to develop FarmLens to better cater to your needs as a user, and we've had requests to be able to download the individual bands of a multispectral image directly from the website. At the time of writing this, we are working hard to develop such a feature, but for now, you can access the individual bands of a multispectral upload for something like a RedEdge or Sequoia camera.
First, you'll need to download QGIS or any other similar software that allows you manipulate geospatial data: http://www.qgis.org/en/site/forusers/download.html
- Log in to FarmLens and go to the flight you wish to download the data for. You can always find your data through the View -> Completed -> Map/List pages.
- On the "Download Products" page, you'll then notice that there is a "Band Order" near the top:
This tells you the order of the bands of the geotiff that you can download from the "Stitched Image" section. This is important to note (or just leave the tab open). Select a tiff from the dropdown box on the left and click "Download".
- Unlike a normal image, which either has a single band (grayscale) or 3 bands (R/G/B), this image will have a number of bands equal to the number of bands of your camera, most of these will have one additional channel which is the 'alpha' channel or the transparent channel. Using gdalinfo (a command line utility, not required for this) on the download from above, you can see that there are 5 bands:
These correspond to the band order from the previous step: Band 1=GRE, Band 2=NIR, Band 3=RED, Band 4=REG (or red edge), Band 5=Alpha. If you have GDAL, and want to use the command line, you can use gdal_translate (below) to split out bands, otherwise the next steps will cover how to do it with QGIS.
You'll also find the band order on FarmLens on the download products page:
- Now start "QGIS Desktop", it's icon resembles the following:
- Click the "Add Raster Layer" button from the left hand side:
Browse the the geotiff you downloaded from earlier, and it should appear in the map (possibly as a strangely colored image, this is just QGIS being nice to give you something to look at).
- From the menu at the top, select Raster -> Conversion -> Translate, and this will open a dialog, you'll need to (1) select an outputfile, then (2) click the pencil to edit the text box at the bottom:
In the text after "gdal_translate" you'll want to type -b <BAND NUMBER> -b 5. The band number corresponds to the listing from above (for example, use -b 1 -b 5 if you wanted the GRE band). You can see the example command at the bottom of this page.
- Click "OK" and you'll now have your geotiff loaded into the interface and saved to where you specified
How to use gdal_translate to extrapolate bands:
gdal_translate SequoiaTest_StitchedNIR.tif -b 1 -b 5 -of GTiff -co ALPHA=YES test.tif
The "-b 1" corresponds to the GRE band (so replace with which band you want) and the "-b 5" corresponds to the alpha band. The above command will then output a new file called "test.tif"
Please sign in to leave a comment.