While camera systems such as the DMSV can sample a large area, the spectroradiometer is intended to sample a single point, or pixel. Spectrographs can be used to identify portions of the EM spectrum that are of the most interest for a given project. Imagery taken by the DMSV is comprised of pixels. Each pixel has four datums associated with it, representing the four cameras used to photograph a given site. The spectroradiometer samples a single pixel across a range of EMS values, many more than the 4 points than the DMSV samples.
Spectrographs allow the DMSV to be utilized with greater efficiency.
It should be noted that spectrographs are not constant. The signature for a plant species can change with the time of day, season, year, environmental conditions, or other factors. Hence, it is important that the DMSV and spectrograph be taken at as close to the same time as possible. This can make preliminary work difficult, but experience with a site or given environmental parameter can make the choice easier. In addition, spectrographs can be collected from the air if information averaged across an entire site is desired.