The goal is to feel you are inside the painting

Just found this VR app which inspirate the idea behind. These guys did a huge work. What I’m looking is a more fast process but still realistic…to be used mainly for landscapes paintings, not human paintings.
Perhaps VR painting is a way to do so but UE4 grass and vegetation is already there, just need to adapt the painting materials to the vegetation.
Still looking for a effiecient process to follow.