Explanation of the optimization equation

[JinraeKim]

In this paper, I cannot guess the meaning of variables in Eq. (1).

I guess E_D is at least the sum of squares of depth errors. What is v(p, q)? How can we pick p and q from image N for E_N and E_S? What is T_{obs} in E_D?

Please give me an explanation with an example.

[JinraeKim]

Also, how did you approximate the equation? There is a reference paper but the notations are different and looks not enough to guess the approximation