Update on imposters!... the maths are not as easy as I thought, but there's a bit of progress... I haven't had a lot of time to tweak all the stuff and also had to resort to a bit of shameful curve fitting of utter shame but hey, legend says when desperation comes even pros like Planck would curve-fit
That's the texture tile Y offset precalc correction: sin(x*-3)*.25+0.5, and nope, I've no frigging idea why it's asymmetrical . Also, before you say it should have a pi cause of that 3, take my word for it, it doesn't (kids these days... they see a 3 in any trig and think it should be pi ). It's possible I'll have to revamp all the math using a simpler approach because there are too many corrective offsets.
Anyway, accuracy is OK although there's no perspective correction (on the quad projection, not the texture obviously) but I don't think that's necessary anyway because it's for far stuff, possibly last LOD level:
Transitions are acceptable already imho, with a bit of fading they should look fine:
These are some typical scenarios:
Here's a more realistic test with lots of transitions (sorry jumpy FPS camera ):
We're gonna have the most badass imposter system ever :P.