There are many different geometric compositional systems such as the golden ratio or the rule of thirds. In this case we are starting with a square image and will therefore use a ratio of the square root of two: the ratio between the diagonal of the square and the side of the square.
'Winter Light' mixed media painting with regulating lines
As you can see, the elements of the composition are arranged within a framework of related ratios. The relationship between the the dimensions shown in the image can be expressed mathematically: