When you talk about the gravel/grass transition ("wider transition with continuously changing average material coverage") do you mean that the gravel and grass will be "blended" to varying degrees, ie seeing patches of gravel intermixed with grass in the "transition area"? At the moment the gravel/grass transition is still a "hard edge" even though its not straight line.
Well, kind of. Remember we want naturally looking transition on
all detail levels, so if you want a less hard edge from the distance, how will the same edge look up close? If it was done in a classical way, it would be one ugly blend of two materials across 2 meters distance. But that's not natural in any definition of naturalness
Let's take it to a more contrasting area first. The same thing applies to transitions between climate types. Surely a transition from savanna to a desert doesn't mean that up close there's a Schrodinger's cat of a half-grass half-sand green-yellow blend of materials, yet from the distance it looks exactly like that: a varying blend of grass and sand colors.
Up close, though, you'll initially find patches of sand between grass, gaining on average surface area as you progress deeper into the desert, until there are just patches of grass in the sand, gradually diminishing further in.
That's what I call fractal blending: from distance it gives the expected colors of blending materials, but up close the edges are still hard, of well defined materials. Only a thin blending stripe to reduce noise from aliasing.
Is it possible for Outerra to support custom textures? Runways have a lot of variety with regard to their markings and material.
The same question applies for cloud/road/land textures. If you're interested have a look at REX (http://www.realenvironmentxtreme.com/) to see how FSX/Xplane textures can be extended by 3rd parties.
Please consider supporting similar texture moding for Outerra.
It is possible, but it has to be made compatible with the procedural system in order to be able to generate the ground-level detail.
In FSX/Xplane you are just throwing amounts of textures at the system, it's about streaming heaps of data and you have to have an autogen to get the detail everywhere. We are aiming for persistent and exactly defined world.
In short it's different and old principles cannot be applied directly, but we want to provide tools that will make it possible in a way.
Markings are another matter - they can be added as vector overlays.