Left: ratios between the derived mean density within ﹩| Z| \lt 50﹩ pc from the mock data and the input mean stellar mass density within ﹩| Z| \lt 50﹩ pc (solid line) or the input midplane density (dashed line). Right: ratios between the derived and the model input surface mass density. For both the left and the right panels, the red symbol shows the result of the whole stellar population of 0–14 Gyr. The horizontal lines delineate the constant values of 1.0 and 1.2.