If you traced the illustration, there could be some question. But if you looked at and even measured photos of hats and then created entirely original illustrations, then you are in the clear.

Perhaps the critical part is that there are so many photos of Mountie hats, you might have copied any one of them, so no photographer could prove that you’d copied her or his photo.

But in any case, you are always free to illustrate what you see, so since you did not copy nor trace, you have nothing to fear.

Just my own non-lawyer understanding of the case.