NDVI*& Real World Apps
On a large farm, the inspection of crops can be an overwhelming task. How can a farmer other than walking the fields or renting a helicopter ever be able to tell how his crops are doing.
The land especially in Illinois is very flat with no rolling hills to climb onto to have a look to see how the crops are preforming.
Crops are a farmers livelihood, so if they are not producing there is money that is thrown away. Early detection is the key.
If there are large acres that are not growing or growing slower than others, the areas can be pinpointed and inspected to figure out what the best course of action should be.
Agriculture is using technology more and more every day.
Top drones for this type of work need to have Global Positioning Satellite (GPS), First Person View (FPV), stabilized gimbals, excellent cameras and even autonomous waypoint navigation.
The drones listed below can be used to survey crops, fencing and buildings as they have terrific cameras mounted on the best stabilized gimbals. These drones can also build elevation models and photogrammetry maps using software such as Pix4D.
They can also be adapted to carry multispectral sensors such as the Sequoia UAS sensor* and the Canon S110 NIR.
*Sequoia UAS sensor is a small, light multispectral sensor that captures images across four defined, visible and non-visible spectral bands, plus RGB imagery, in just one flight.
*The Normalized Difference Vegetation Index (NDVI) is an index of plant “greenness” or photosynthetic activity, and is one of the most commonly used vegetation indices. Vegetation indices are based on the observation that different surfaces reflect different types of light differently.
Photosynthetically active vegetation, in particular, absorbs most of the red light which hits it while reflecting much of the near infrared light. Vegetation which is dead or stressed reflects more red light and less near infrared light. Likewise, non-vegetated surfaces have a much more even reflectance across the light spectrum.
By taking the ratio of red and near infrared bands from a remotely sensed image, an index of vegetation “greenness” can be defined. The NDVI is probably the most common of these ratio indices for vegetation.
NDVI is calculated on a per-pixel basis as the normalized difference between the red and near infrared bands from an image.
NDVI can be calculated for any image which has a red and a near infrared band. The biophysical interpretation of NDVI is the fraction of absorbed photosynthetically active radiation.
MIT Technology Review: Agricultural Drones: Relatively cheap drones with advanced sensors and imaging capabilities are giving farmers new ways to increase yields and reduce crop damage. (https://www.technologyreview.com/s/526491/agricultural-drones/)
UAV Precision Agriculture (http://www.asctec.de/en/uav-uas-drone-applications/uav-precision-agriculture/) “Due to consistent improvement today the AscTec Falcon 8 is one of the most advanced high-performance drones worldwide”.