In: Wagner W., Székely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Voi. XXXVIII, Part 7B 
This research was conducted in the rice research institute 
in Amol in the north of Iran. Spectral field measurements 
of seven different cultivars were acquired on different 
plots (Figure 1). A total of 76 spectrums from rice 
cultivars named Hybrid, Tarom, Neda, Nemat, Shiroudi, 
Khazar and Fajr (10-12 sample for each cultivars was 
measured) were analyzed. Figure 2 shows the crown 
canopy of each cultivar to be measured. A full range (350- 
2500 nm) portable spectroradiometer (ASD FieldSpec Pro 
FR) was used for spectral measurements. The field of 
view of optical sensor was 25 which positioned 30-40cm 
above the samples at nadir position. The measurements 
were conducted under clear sky between 10:00 and 14:00 
local time in 27 August 2007. The noise spectra in water 
absorption feature wavelength was removed based on 
standard deviation calculated of all reflectance values in 
each wavelength. The first derivative spectral curves 
calculated in Matlab software and the red edge position in 
this spectral range extracted based on the specified 
maximum slope. 
fsd a = 
ftl+l - fí A 
Al 
FSD: First Derivative at X wavelength 
R: Reflectance 
Figure 1: Spectral filed measurements of rice varieties 
Shiroudi 
Nemat 
Neda