I apologize in advance for my lack of knowledge. I don't know a great deal about working with this program, so I'm learning as I go. I am wanting to take the free Landsat data that I have downloaded and turn it into a NDVI shapefile for use in another agriculture program.
I have downloaded the data and imported Bands 4 and 5 into QGIS. Since this is for a particular field, I used a shapefile of the field boundary to clip the image. I then used the Raster Calculator to generate a GeoTIFF using the expression (Band5-Band4)/(Band5+Band4). I also changed the layer properties so that I can visualize the data on a RedYellowGreen scale. This looks good so far.
I now need to turn this clipped GeoTIFF into a shapefile so that I can import it into my other program. I have tried the polygonize (Raster to Vector) but this doesn't seem to give me what I am needing. Could someone point me in the right direction, please?
Best Answer
As Kazuhito suggested in the comments I guess you get what you want by using the "Raster values to points"-tool (from Processing toolbox -> SAGA). You keep your original NDVI cell values and get the according x/y-coordinates for each raster cell. By selecting "type: [ 0 ] node" you get points (center points), and by "type: [ 1 ] cells" you get polygon features for each raster cell.
You can change the style in the output shapefile symbology to a graduated style by using the classify function to vizualize the NDVI variation.
By the way, I used QGIS 2.18.2