I'm reading an illustrated theory of numbers by Martin H. Weissman, on page-233, it is shown how to expand out a domain topograph starting from basis $\pm (17,12)$ and $\pm(7,5)$
I understand that the basis idea is that if $\{v,w\}$ are independent, then so are $\{v+w,w\}$ and $\{v-w,w \}$. But, I don't understand how the above was expanded further:
How did we get the blue edges from the greens?