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The geometric decay factor, as an important part of the two-way reflection model, has an important modulating effect on the model. The integral geometric attenuation factor uses the normal distribution function of the microsurface elements for integration, which eliminates part of the unreasonable inflection point problem in the Blinn geometric attenuation factor in the curve. However, the integral geometric attenuation factor only considers the shading or shadowing effect under the same conditions, and the curve still has inflection points at the critical point between the shadowing and shading effects, especially at large incidence angles. To address these problems, under the same detection conditions, the detector detects a collection of reflected light from a large number of different microplane elements in the field of view, and the effects of masking and shadowing effects should be considered comprehensively. In the integral calculation of the reflected light from the microplane, it is necessary to assign the proportion of the incident light incident to each microplane element to the total incident light. The proposed modified integral geometric attenuation factor model, which is the product of the proportion of incident light striking the respective microplane element as a percentage of the incident light and the light intensity received by the detector from that surface as a percentage of the light intensity incident to this surface. The modified integral geometric attenuation factor model is compared with the integral geometric attenuation factor model, and the two-way reflection function curve of the modified integral geometric attenuation factor is compared with the measured two-way reflection function data by numerical simulation. The numerical simulation results show that the modified integral geometric attenuation factor model fits better with the measured two-way reflection function data, and can suppress the divergence trend of the integral model at large reflection angles.
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