The fraction of absorbed photosynthetically active radiation (FAPAR) characterizes the energy-absorption ability of the vegetation canopy. It is a critical input to many land-surface models such as crop growth models, net primary productivity models, and climate models. There is a great need for FAPAR products derived from remote-sensing data. The objective of this research is to develop a new instantaneous quantitative FAPAR model based on the law of energy conservation and the concept of recollision probability ( ). Using the ray-tracing method, the FAPAR-P model separates direct energy absorption by the canopy from energy absorption caused by multiple scattering between the soil and the canopy. Direct sunlight and diffuse skylight are also considered. This model has a clear physical meaning and can be applied to continuous and discrete vegetation. The model was validated by Monte Carlo (MC) simulation and field measurements in the Heihe River basin, China, which proved its reliability for FAPAR calculations.Index Terms-Clumping index, FAPAR-P model, fraction of absorbed photosynthetically active radiation (FAPAR), recollision probability ( ).
High Efficiency Video Coding (HEVC), a successor to H.264, is the next generation video compression standard. To enhance the coding efficiency of video frames, 35 intra prediction modes adopted in Prediction Unit (PU) from 4x4 to 64x64 of HEVC. However,the improvement is based on the cost of rapid increased complexity performance loss. This paper proposed a Pixel Gradient Statistics (PGS) and Mode Refinement (MR) based fast mode decision algorithm. PGS use pixel gradient information to assist prediction mode selection after Rough Mode Decision (RMD). MR utilizes neighboring mode information to select most probable mode (MPM). Experiment result shows that the proposed method performs about 28% time saving with little degradation (BD-rate increase 0.53% and BDPSNR reduce 0.038) in the coding gain.
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