There are many cameras that can be used for estimating the health of plants:
- Radiometric, narrow band cameras
These cameras were designed to be as accurate as possible when measuring the reflectance of plants, and come either with sensors or a calibration target to properly estimate the sun's effect in order to get absolute values. Such cameras include Sequoia, Multispec 4C and Micasense RedEdge.
- Modified standard cameras
By carefully changing the filters of a normal camera, it is possible to get wide band infrared measurements. However, it is critical to follow a certain workflow to obtain somewhat accurate relative measurements (see 204894705 ). Many companies offer to either modify cameras or sell already modified cameras.
Pix4Dmapper can process both types of imagery. The choice of filter/band depends entirely on the intent. For example, the red and NIR bands are most suited to compute NDVI (related to the health of the plant), and red edge bands are appropriate for the Chlorophyll Index (related to the amount of chlorophyll in the plant).
It important to note that despite their low cost and easy availability, modified cameras' results are much more complicated to interpret, the accuracy is hard to assess and the results may vary significantly with time.