Van Gogh was heavily inspired by Japanese woodprints, which often utilized 1-point perspective, leading to a sort of "flat" look. When it comes to his understa

Van Gogh was heavily inspired by Japanese woodprints, which often utilized 1-point perspective, leading to a sort of "flat" look. When it comes to his understanding of perspective, Van Gogh was so obsessed with realism that he never drew from imagination and even used/invented his own physical perspective grid to check his work. And for why his work might appear "amateurish": this was a deliberate style choice by Van Gogh. He was a person who wanted to disguise his expertise. In one of his letters, he notes to a fellow artist that he wants his work to draw people in who "swear he has no technique" and be so "savant" that his work almost appears naive and does not "reek of its cleverness". He's trying to fool us.