Why use Pixels or Panels? lol
Numbers are like 60-70 Meters Tall
Based on how many Floors there are & Interior of Skull Dome, it's clearly +1000 Meters from Sea Level to Rooftop
As for Length, just inside Castle, Numbers looked Normal Sized there, You can put Dozens of Sleeping Numbers lined up there lol
And Live Floor was even Bigger, not to mention the Rear Entrance & where Zoro/King Fought
Adding the Areas covered by Mountains & the entire Port/Etrance, Onigashima is clearly a Huge Island
It's made for Ancient Giants, not Humans
U want to compare with Marineford? Marineford HQ was clearly not made for likes of Sanjuan Wolf. His Max Size is 180M
No need to Scale anything, They are simply Islands made for Races of Different Sizes