The objective of this study is to develop a monitoring system of crop status for precision
farming. A Multi-Spectral Imaging Sensor, which can get three wave length images(R, G and NIR)
simultaneously, was used as the imaging sensor of this system. Field test of this system was carried
out at the paddy field with an unmanned helicopter. Geometric correction by converting from image
coordinate to global coordinate was performed by the data of RTK-GPS and inertial sensor. After
obtaining field images by the system, leaf height, stem number and SPAD value were measured by
conventional method as ground truth. From this result, it was clear that stem number can estimate
from Vegetation Cover Rate which expresses the cover rate of crop within an image. Additionally, It
was also clear that SPAD value can be estimated from Leaf Color Index calculated from the
corrected R image.