I'm still a little bit lost as to what a 4D light field really is, any further explanation on this would be helpful, thanks!
Is it that with photographs, we only capture the irradiance wrt pixels on a fixed 2D plane, whereas Light fields try to do something more - for a 2D set of sensors, detect the radiance from each ray/direction (adding another 2D for total of 4D)? And this extra info allows us to do more interesting things and modify our photos in a way we couldnt do with a normal static photo? Something along those lines?
Bit unsure about how exactly the 4D number comes about - what exactly is each dimension for? above was my guess for it.
Actually, slide 27 of this lecture gives some more explanation/insight into this