Relative diffuse reflection measurements from the original and ground surfaces using a He-Ne laser are reported. The intensity measurements for the metallic, transparent dielectric, matte plastic surfaces and colored papers are presented. Our results indicate that among metallic surfaces tested, aluminum has the highest diffuse REFLECTANCE; while the original stainless steel surface shows the lowest. The primary result is that for the ground metallic surfaces, there seems to be an optimum condition and roughness that result in the maximum diffuse reflection. For the color matte plastics, the yellow color has the highest diffuse REFLECTANCE and the black one shows the lowest. For the colored papers the yellow paint shows a maximum diffuse REFLECTANCE; whereas the gray one has the lowest diffuse REFLECTANCE. Our results agree with the theoretical predictions and also with the other experimental results.

The non-context-based approach is used for the synthesis of spectral REFLECTANCE curves of objects with known CIEXYZ tristimulus values. The method introduces two sets of features, i.e., the standard color-matching functions normalised by their sum in each wavelength and a group of two sigmoidal and one Gaussian bases that approximately fit the first set. The assigned spectra for the desired tristimulus colorimetric values are calculated using an additive color-mixing approach. Results of different methodologies are numerically compared in terms of root mean squared error (RMSE), goodness fit coefficient (GFC), and CIELAB color difference values between the actual and synthesised spectra. It is found that the synthesised spectra by the suggested primaries better resemble the actual behaviours of spectral REFLECTANCEs of natural and synthetic objects in comparison to using three Gaussian primaries. Compared to other context and non-context-based approaches to spectral reconstruction, the suggested method is faster and does not require iterative optimisation.

Rice cultivated areas and yield information is indispensable for sustainable management and economic policy making for this strategic food crop. Introduction of high spectral and special resolution satellite data has enabled production of such information in a timely and accurate manner. Knowledge of the spectral REFLECTANCE of various land covers is a prerequisite for their identification and study. Evaluation of the spectral REFLECTANCE of plants using field spectroradiometry provides the possibility to identify and map different rice varieties especially while using hyperspectral remote sensing. This paper reports the results of the first attempt to evaluate spectral signatures of seven north Iranian rice varieties (Fajr, Hybrid, Khazar, Nemat, Neda, Shiroudi and Tarom plots) in the experimental station of the Iranian Rice Research Institute (main station in Amol, Mazanderan Province). Measurements were carried out using a field spectroradiometer in the range of 350-2, 500 nm under natural light and environmental conditions. In order to eliminate erroneous data and also experimental errors in spectral REFLECTANCE curves, all curves were individually quality controlled. A set of important vegetation indices sensitive to canopy chlorophyll content, photosynthesis intensity, nitrogen and water content were employed to enhance probable differences in spectral REFLECTANCE among various rice varieties. Analysis of variance and Tukey’s paired test were then used to compare rice varieties. Using Datt and PRI1 indices, significant differences (a=0.01) were found among rice varieties REFLECTANCEs in 19 out of 21 cases. This promises the possibility of accurate mapping of rice varieties cultivated areas based on hyperspectral remotely sensed data.