Hello, this is Ondrej from Melown.com.

Actually, Melown is all about scalability. There is no limit to the size of True3D data we can integrate, appart from the disk space available.

To get an idea of what I am talking about, please check out the simple demo at https://melown.com/intergeo2016

Yes, we're talking planetary scale. If somebody had the resources to model the entire planet in 10cm True3D, Melown can carry it, with no changes to the existing architecture.

And unlike Google, Melown can do polar caps too, the same quality as any other place on Earth. And with Melown, you can do Mars, Mercury, Titan, Europa, or any other celestial object, without the limitation of Web Mercator, WGS84 or other simplistic approaches.

It does use quad tree (or similar) tiling. I guess they simply limit framerate to something reasonable instead of rendering as many frames as possible like others often do.