Density distribution of the MaNGA data in the 2D P₁–P₂ diagram, where the relevant parts of the (interpolated) SF model (cyan grid) and AGN model (red grid) appear edge-on and well separated. The sample H II regions are colored from yellow to purple. Here, we only plotted the parts of the model surfaces that cover the middle 98% of the data along the P₃ axis (line of sight), which is perpendicular to the P₁ versus P₂ plane. This projection corresponds to a line of sight at (θ, ϕ) = (36°, 219°) in the 3D space of (N2, S2, R3), where θ and ϕ are the polar angle and the azimuthal angle, respectively (Ji & Yan 2020).