Preharvest Monitoring of Biomass Production - Engineering and Science of Biomass Feedstock Production and Provision - page 66

4.6 Near-Real-Time Remote Sensing

Satellites and piloted aircraft-based remote sensing systems are the two major plat-
forms that have been commonly used to collect remote sensing image data. Current
limitations for the conventional image-based remote sensing platforms are due
mainly to coarse spatial resolution, slow turnaround time, inadequate repeat cover-
age, and high cost [ 20 , 21 , 27 ]. Most importantly, since agriculture is very dynamic,
remote sensing data must reach the farmer in near real time. However, this is rarely
the case now [ 28 ]. Sawyer et al. also pointed out that the biggest diffi culty in imple-
menting variable-rate technology (VRT) is the lack of a reliable and consistent
method of obtaining spatial and temporal variability data from a fi eld [ 29 ]. To deal
with the problems that exist in current remote sensing platforms for biomass prehar-
vest monitoring, near-real-time remote sensing is necessary and subsequently needs
to develop site-specifi c monitoring for biomass energy crops.
As indicated in Fig. 4.5 , three near-real-time site-specifi c remote sensing sys-
tems for biomass preharvest monitoring are possible: (1) stand-alone tower-based

Fig. 4.5 Near-real-time remote sensing system for biomass energy crop site-specifi c monitoring.
( a ) Tower. ( b ) Ground reference data collection vehicle. ( c ) UAV-based remote sensing