Here is a "trick" for transpiring proportions where the aspects are unknown. Take a dominant feature from a representation of the object and trace the length of it onto a piece of paper. Assign that stripe its value which could be an estimate of the actual object but doesn't have to be, 1.5 meter for example. It's a simple matter then of halving that length and in turn halving all consequent subdivisions until you have a number of elements for making comparisons all derived from the original measure and so proportional.