Graphical representation of a v6 address space usage

Hi ! I'm trying to put together some statistical data about the allocation status of a (rather large) IPv6 LIR range. I'm used to representing v4 address space using Hilbert curves, but it's not really optimal for IPv6 as the allocated space is too sparse, and the unitary allocations way too small to label them on the graphical representation. So I'm looking for "graphical representation best practices", such as an anamorphic scaling algorithm to draw a more readable map while still pointing out the vast amount of free space remaining with a non proportionnal surface. Did anyone see such a tool ? Thanks ! -- Jérôme Nicolle