That patches of you are new? 
I s’pose that’s so (new skin).
I don’t think the same places are necessarily used each time by whomever does the aerial mapping where I live, so that’s why I was ‘huh’ about the markings being permanent. However, I can certainly see that it would be beneficial to make them so. I’m not surprised that other places do.
>That patches of you are new?
Or appear so. I’d take that. Though, I did get two slices of dead guy bolted into my neck last month, so they’re new to me, right?
Quite frankly, it varies.
Some are laid out in a regular grid, for mapping.
Others are laid out for highway planning routes (plastic is sometimes used here).
The issue of waiting until early Autumn, & shooting new film until Late Spring–spot on. No good taking photos if trees & heat shimmer make good photos impossible.
BTW–there are “L” shaped marks laid out, too.
djgrendellv: Are there more than one of them in your parking lot? If so, is there any discernable pattern to them or distance(s)/alignment between them?