The issue of scattering effect is common in imaging and optical 3D measurements, which introduces global illumination into the classical geometrical optics model. Separating the interested information from complex global-direct illumination often poses significant challenges. However, to suppress the global illumination, the conventional polarized modulated method generally requires manual adjustment to obtain multiple signals, which strictly limits the real-time detection and adaptability. To solve this problem, based on our analysis for the intensity distribution of four channels of the polarization camera from Malus's law, we establish a polarization angle shifting (PAS) model and further propose a separation strategy to efficiently achieve global-direct light transmission component pixel-by-pixel separation with a single exposure. And the proposed method eliminates the limitation of the linear polarization of the light source. With the proposed method, we could obtain contamination-free phase of scattering interface and global information imaging. Experimental results in a structured light measurement system confirm the effectiveness of the method for separation imaging, and the final de-scattering 3D phase results are also shown.