Calculation process for the extinction of the example subfield (l, b) of (0.0, +1.0). From upper left to lower right, they are a) the errors of [3.6] vs. the [3.6] diagram, b) the color Ks–[3.6] vs. distance diagram, c) the extinction at [3.6] vs. the distance diagram where we show the first initial guess of extinction after the first iteration (black) and the final iteration after 20 loops, (red) and d) the color Ks–[3.6] distribution of the data compared to the first guess iteration (black) and the final one (red).