The central subject of Van Gogh's Olive Trees series changes from season to season, painting to painting, and perhaps even reality to dreamscape. In "Olive Trees with Yellow Sky and Sun," the perspective appears to be three-point, with the mountains set in the background, the trees arranged in grove rows from front to back from the painter's view, and the yellow sun above and behind the whole scene. The sun above and behind the scene is the point to which the other lines connect, which is what makes it a three-point perspective.
In terms of the painter's/seer's view, it would be acceptable to consider the canvas a normal-view perspective. However, we need to also account for the magical realism inherent in many of Van Gogh's works. The canvas may be normal-view—the view Van Gogh saw when looking out into the grove—with a few embellishments. Or, it could be painted from dream, memory, or fantasy.
While we do not know the intent behind this painting specifically, in a letter to fellow artist Emilie Bernard, Van Gogh wrote:
So at present am working in the olive trees, seeking the different effects of a grey sky against yellow earth, with dark green note of the foliage; another time the earth and foliage all purplish against yellow sky, then red ochre earth and pink and green sky. See, that interests me more than the so-called abstractions.
Therefore, though some have pointed to irregularities in shadowing based on the foliage and time of year, if we take the artist at his word, the painting is meant to be literal or near-literal.