# Bilinear Interpolation (BI) Algorithm

Four gain values are determined in the horizontal and vertical patterns depending on the two angles $\vartheta $ and $\phi $ .

Four gain values are determined in the horizontal and vertical patterns depending on the two angles $\vartheta $ and $\phi $ .

The gain values are weighted with their angle distances:(1)
$G(\phi ,\vartheta )=\frac{\left|\phi \right|\cdot {G}_{v}(2\pi -\vartheta )+(\pi -\left|\phi \right|)\cdot {G}_{V}(\vartheta )+\vartheta \cdot {G}_{H}(\phi )+(\frac{\pi}{2}-\vartheta )\cdot {G}_{V}(0)}{\left|\phi \right|+(\pi -\left|\phi \right|)+\vartheta +(\frac{\pi}{2}-\vartheta )}$