Note that not all of the identified parameters are necessarily suitable for green-from-green discrimination. The slope values S1 and S2 provided reliable green-from-green discrimination under static conditions in a controlled laboratory environment. However, in a dynamic outdoor environment it was found that platform dynamics and factors affecting reflection, such as the distance of the sensor from the leaf, the orientation of the leaf
and the exposure time of the line scan sensor, collectively resulted in varying reflected laser intensities, which thwarted the usefulness of these two parameters. Data normalisation was able to remove many of the aforementioned factors and the NDVI635 and NDVI685 parameters were more reliable discriminants than the RDI parameter. It was experimentally found that, when an incident beam was illuminating a leaf, the variability in the red laser peak values led to errors in the measured spectral properties. With low red peak values, the variance of the RDI parameter was significantly larger than those of the NDVI parameters. This discovery discounted the use of the RDI parameter as a discriminant.