I am experiencing a problem regarding the NDVI values I have acquired after conducting aerial imaging over a sugarcane plot using a modified RGN, CHDK-enabled Canon SX230 camera (Rosco Fire #19 filter). I am also using a card (contained in the Infragram Kit) to calibrate (customize white balance) the camera under a shaded location.The NDVI values I have acquired ranges from -0.336 to 0.106 only. This was taken under clear skies.
Studies have commonly used an NDVI scale where: < 0.1 = barren rock, sand, snow, or water; 0.2 to 0.5 = sparse vegetation such as, shrubs or grasslands; 0.6 to 0.9 = healthy, dense vegetation. Following this scale, would this mean that the NDVI value I took meant that the sugarcane crop is very unhealthy or dead?
Below is a sample of the raw (left) and recolored image of the plot.