There are actually several answers I will give to the question of how did the undulating line of bushes get turned into rectangular shapes.
One answer is that, in general, I seem to prefer square shapes more than round. I really don't know why that is. I have heard that straight lines (and I am going to attach square/rectangular shapes to that as well) are more masculine and curves (circles) more feminine. As a friend said to me one time, maybe I am expressing my masculine side. It would make sense. I am definitely not a "girly-girl." That doesn't mean I will never use curves or circles, it just means that I seem to prefer the other.
(Just as an aside, I cut all the seams free-hand on this piece so they aren't ruler straight. I am really trying to get away from that because then the line is more like a drawn line.)
Another answer to the question is that sometimes when I see something, like the scene in the photo, an abstracted image pops into my head. And if it is persistent, then I need to get it out of my head and onto paper. Many times it is already a fully formed image.
The last answer is that sometimes there is a progression through the sketching process. It can be like brain storming - just trying out different ideas, or working through one particular idea in different ways.
I didn't actually show you every single step in the process. What I left out in the last post were the sketches that came before I decided on that final one I showed you.
I hope that answered the question. If you have more let me know.
(Also, if you do leave a comment, but don't have a Blogger account, then I can't reply to you directly with an email, but will do so here in the comments. So you might need to check back.)