In an artwork using perspective, at which point do the orthogonal lines in the work merge? in an artwork using perspective, the orthogonal lines in the work merge at the point.

In an artwork using perspective, the orthogonal lines in the work merge at the vanishing point. 

These lines are used to maintain a perspective which means giving the art a realistic view of the object/s. The vanishing point is a point that stands at eye-level on the horizon. There can be either one or more vanishing points and thus derive the terms “one-point perspective”, “two-points perspective”, etc.