Ground reflectance measurement techniques: a comparison.
The relative accuracies of reflectance factor measurement methods involving the simultaneous, as compared to the sequential, measurement of irradiance on and radiance reflected from the target are discussed. Data are presented to support a statistical demonstration that the simultaneous measurement technique is the more accurate.
Estimating the irradiance spectrum from measurements in a limited number of spectral bands
Accurate measurement and characterisation of fluctuations in the irradiance environment is important for many areas of optical remote sensing. This paper describes a method of estimating spectral irradiance over the region 400 – 1000 nm from the radiance of a calibrated reference panel, measured in four narrow spectral bands (FWHM approx.10 nm). The reproducibility of the method was found to have an average root mean squared error of approximately 30 mWm-2nm-1 over the region 400 nm to 1000 nm when applied to spectra covering a range of clear sky conditions typical of mid-latitude temperate regions.
Remotely-Piloted Helicopter Citrus Yield Map Estimation
A remotely-piloted Gas Xcell mini-helicopter with GPS, wireless Ethernet, and a machinevision system was flown over orange trees to take overhead images. The individual tree images were processed to estimate the number of orange pixels in the images. The fruit yield of individualtrees at harvest a month later had an r-squared value of 0.373 with the number of orange pixels onthe irrigated tree images. While it was demonstrated that a remotely-piloted mini-helicopter could beused to acquire useful overhead images of citrus trees, substantial further research is needed toimprove the accuracy of estimates of individual tree yields or health.