A page of memories drawn by AI

I asked an AI to generate an image of a character from a novel I really loved when I was young, and it produced something quite convincing. I don't know why, but the moment the image appeared, I felt a lump in my throat; I guess I really did love this novel.
It's a novel that any old guy who likes fantasy would probably know... Is there anyone who can guess what this novel is?
This is a camping scene featuring the four main protagonists.