cutter, defence platform 30-50m
cruiser, starbase 100-200m
titan,star fortress -1000m
I claim no graphics expertise, but aren't these numbers a little extreme? I mean , if the projection of the leviathan takes up about 80x40 pixels on your screen, then a cutter is just 2x1 pixels.
Also, if we are doing it in 3d, then a player is going to see a Leviathan being about 64,000 times the size of the cutter. I'm pretty sure the in-game volume differences won't work out to be anywhere near that extreme.
If the plan is to scale up the smaller sizes to be more in line with game volume and cost, why not allow people to design them in more consistent scales to begin with?
I'd say maybe:
Cutter - 300m
Frigate - 500m
Cruiser - 800m
Battleship - 1100m
Titan - 1500m
Leviathan - 2000m
The 'volume' that people see would then be around: 1, 5, 20, 50, 125, 300