Bidirectional reflectance is a fundamental property used for the analysis of radiative heat transfer. It is a form of reflectivity in which the spectral and directional dependencies of both the beam incident on a surface and the beam reflected from the surface are specified. A new system has been designed expressly for measuring bidirectional reflectance of engineering materials. This apparatus features a unique goniometer design in which the source is fixed, the sample is rotated to change the incident beam directions, and the sensor (which moves with the sample) is rotated about the sample to change the measured reflected beam direction. The system was used to measure the bidirectional reflectance of a surface consisting of flat-white paint on an aluminum substrate. The data for this quasi-diffuse surface were taken over a non-uniform grid. Algorithms are presented for interpolating and reporting values on a uniform grid which is appropriate for use in numerical radiative transfer codes. Bidirectional reflectance data can be used in the form of a look-up table although storage requirements will be large and resolution will be limited by grid resolution. Alternatively, the data can be modeled as continuous functions of the incident beam angle. A simple model of reflectance as the sum of a diffuse and a specular component is described. A second model with a diffuse component and a quasi-specular component is also presented which includes spread in both the polar and azimuthal directions. Both models are continuous and are based on curve fits to the data. / Graduation date: 1994

Thesis (M. Env. St.)--University of Adelaide, Centre for Environmental Studies, 1989. / Two coloured folded plates in pocket. Includes bibliographical references (leaves 97-107).

Thesis (M.S.)--Rochester Institute of Technology, 2005. / Typescript. Includes bibliographical references (leaves 93-96).

Thesis (M.A.)--Carleton University, 1992. / Also available in electronic format on the Internet.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Dale J. Bremer / Radiometric methods may provide more objective and quantitative assessments of turf quality and density than visual ratings and may be useful in measuring green leaf area index (LAI), aboveground biomass, and chlorophyll concentration. This three-year study was conducted near Manhattan, KS to examine: 1) relationships between canopy reflectance and visual quality and density ratings in four cool-season grasses tall fescue (Festuca arundinacea Schreb.), Kentucky bluegrass (Poa pratensis L.) and two hybrid bluegrasses (HBG); 2) effects of species, mowing height, and irrigation deficit on relationships between visual quality and reflectance; 3) comparisons of visual quality with reflectance and digital images of individual plots; and 4) relationships of LAI, aboveground biomass, and chlorophyll concentration with canopy reflectance in the same four grasses and in perennial ryegrass (Lolium perenne), zoysiagrass (Zoysia japonica Stued.), and bermudagrass [Cynodon dactylon (L.) Pers.]. Reflectance was strongly correlated with visual ratings in the normalized difference vegetation index (NDVI, [935-661]/[935+661] nm, r = 0.88), the near infrared to red (NIR/R [935/661] nm, r = 0.83), Stress1 (706/760 nm, r= 0.84), and Stress2 (706/813 nm, r= 0.70) ratios and at wavelengths 613 (r= 0.74) and 661 nm (r = 0.80), but correlations varied among years at each wavelength and vegetation index. For density, highest correlations were in NDVI (r=0.86), R661 (r=-0.84), and Stress2 (r=-0.82). Regressions between reflectance and quality and density ratings indicated cultivar- and mowing height-specific models. Irrigation-deficit strongly affected reflectance in KBG and both HBG but not in TF, indicating greater sensitivity to drought of bluegrasses than TF. Digital images indicated strong correlations between percentage green cover and visual quality (r=0.89). However, wide ranges in visual quality were observed in plots with similar green cover or NDVI for reasons that are not apparent. Correlations of LAI, aboveground biomass, and chlorophyll concentration with reflectance were strong in some species at different wavelengths and ratios. Results indicated both potential and limitations in using spectral reflectance to estimate turfgrass canopy characteristics.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Master of Science / Department of Agronomy / William T. Schapaugh Jr / Sudden Death Syndrome (SDS) in soybean, (Glycine max ( L.) Merr.) caused by Fusarium virguliforme, is an increasing problem in commercial soybean production due to the yield loss associated with the disease. Screening for genetic resistance requires extensive visual evaluations. Canopy spectral reflectance may be an indirect tool for selection of SDS resistance as well as grain yield in large segregating populations. The objective of this study was to estimate SDS resistance and seed yield in large diverse soybean populations using canopy spectral reflectance. Spectral reflectance, disease index, maturity and yield were measured on two populations consisting of 160 nested association mapping recombinant inbred lines and checks; and 140 commercial cultivars with checks. Populations were grown in three environments in 2015 and 2016 with historic SDS disease pressure. Entry, environment, and entry by environment sources of variation were significant for disease index, yield, maturity and spectral reflectance. Changes in season average reflectance were correlated to disease index, yield and maturity. Estimation models of disease index, yield and maturity were created with season averages as well as individual day readings for both populations. Season average and individual day models accounted for 11% to 77% of the phenotypic variation in disease and 41% to 93% of yield variation when measurements were taken at the height of disease pressure. Models for disease index and yield models were able to predict significant portions of the phenotypic variation between entries at most environments. These results suggest that it may be possible to estimate resistance to SDS and grain yield in soybeans using spectral reflectance in breeding populations.

No description available.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [130]-138).

Thesis (M.A.)--Carleton University, 2001. / Includes bibliographical references (p. 90-95). Also available in electronic format on the Internet.