About LLFF_DEFAULT_PSEUDO_INTRINSICS 

LLFF_DEFAULT_PSEUDO_INTRINSICS = Intrinsics(
    fx=700.,
    fy=700.,
    cx=512.,
    cy=384.,
    width=1024,
    height=768,
)
How did you get this variable? Is it the average of the data for each scene in the dataset?

 