Contrastive Analysis Of Slope Plant BRDF And BPDF Spectrum Characteristics

Vegetation occupies a large proportion of the earth surface, and there are quite parts of the vegetation living in the mountains, so slope plants are the main objects of remote sensing detection. Traditional remote sensing assumes that the earth surface is Lambertian, but this assumption is much different from the actual truth. Especially for the detection of slope plants, slope gradient, slope direction, and the detection angle of the detector will affect the result of the detection. With the development of quantitative remote sensing technology, hyperspectral remote sensing and polarization remote sensing gradually mature.So the multi-angles, hyperspectral and polarization remote sensing detection for slope plant is particularly important.For slope plants, in order to in theory further explore which way is better for traditional remote sensing detecting between the BRDF(the bidirectional reflectance distribution function) and BPDF(the bidirectional Polarization distribution function)under the condition of some specific slope gradients, aspects, detection zenith angles and wavelengths, this paper made some related research. This research simulated uniform slope surface for slope plant in a laboratory environment, considering all kinds of slope gradients, aspects and detection zenith angles which may exist in reality. Firstly discuss BRDF characteristics and BPDF characteristics of slope plants, and on the basis of these, take both of them into comparative analysis, and then confirm which is more suitable to traditional remote sensing detection with the influence of different factors. Results show: for BRDF characteristics of slope plants. With the increase of the slope gradient, the reflectance of slope plants first increases and then decreases, and the bidirectional reflectance impact at near infrared band is significantly greater than the impact at the visible band. When only the slope aspect changes, the slope dome gets nearer to the light direction, the reflectance of slope plant becoming greater. And setting the the direction of the light source plane as standard direction, the reflection of slope plant at different aspects which are on both sides of the standard direction appears mainly symmetrical distribution. In the near infrared, with detecting zenith angle increasing, the spectral reflectance of slope plants decreases, and the rate of reduce increases. When only the slope gradient or aspect changes, the BPDF characteristic variation of slope plants is similar to the BRDF characteristic variation. Controlling only the zenith angle change, the polarization characteristic of slope plants is affected by bands, and in different wave bands shows different variation. Comparing the BRDF characteristics and BPDF characteristics of slope plant, to traditional remote sensing, as only the slope changing, using bidirectional reflectance to response the reflection information of slope plants is better than polarized reflectance at 400-2000 nm wave band. With the change of slope aspect, at 400-1328 nm wave band, polarized reflectance of slope plants is more suitable for traditional remote sensing; at 1328-2500 nm wave band, bidirectional reflectance is more appropriate for traditional remote sensing; while at 1328 nm, both of them are under the same degree of influence. When only the detecting zenith changes at 400-1366 nm wave band, polarized reflectance of the slope plants is more suitable for traditional remote sensing, and within 1366-2000 nm band bidirectional reflectance slope plant is superior. At 1366 nm wavelength, both of them are affected at the same degree by detection zenith change.This study mainly focused on theoretical discussion. The findings could provide a theoretical reference for the development of hyperspectral and polarization remote sensing technology, and provide more scientific basis for the application of remote sensing technology in terms of slope plant, furthermore, for plant pest and disease control, forest tree species identification, crop growth monitoring or other researches provide effective support. Meanwhile, this study for the protection of soil and water conservation and ecological environment has important practical significance.