Ok, here's some more RT3 weirdness.
When I did that ramp test
back here, to check out the lowest smooth gradient the game was capable of, I noticed that even though it had a gradient of approximately 1 in 85 the track was shown as being at 0%. So, I decided to run a few tests to see what the game thought various gradients were, compared to what they actually are in terms of in-game mesh. The results are amusing.
Using the same test ramp heightmap, and just playing with the overall height modifier on import, I generated a range of in-game ramps with modifiers varying from 2.6 up to 48.0. Up until 2.6, the game will still show the track as being at 0%. In other words, this supposed 0% track gradient seems to apply to ramps as steep as 1 in 32, in terms of the actual game mesh geometry. That's an actual 3% ramp, still displaying to the player as 0% track.
Track starts getting displayed as a solid 1% at around a height modifier of 8, with a solid 2% kicking in around 16, etc. It looks like the internal calculations are done on the basis that 8 internal height units (which remember are 0.7 of the height units the game displays to you) over the length of one map pixel (the smallest squares visible when laying track) gives you a "track gradient" of "1%" shown in the interface, with the actual gradient of said track being around 8%.
Note that this is still an assumption, because changing ramp height via the overall height modifier on import is not as accurate as changing it directly via the heightmap RGB values. Large modifier values screw things up. Since the original ramp was 1 height unit per map pixel, and was dead smooth, obviously a modifier of 48 should make a smooth ramp of 48 height units per map pixel. It doesn't, though. It gets the top plateau height correct, but the ramp between that and the ocean is badly striated. It's mostly a grade of 6, but grades vary from 1 to 10 in places. At some point I'll probably make a few more RGB ramps to test some of this stuff without having to use height modifiers (IOW, ramps will still be dead smooth) but given the observed results I'm pretty sure the scale suggested is the correct one.
So, in real terms, "0% track" is anything under an actual 1 in 32. "1% track" is about an actual 1 in 12, although with a bit of a range either side of that. "2% track" is about an actual 1 in 6, etc. By the time you're up to "12% track" the actual gradient is near to 45 degrees, which if you check things out in the game is about right.
That's today's first lot of weirdness. The second lot of weirdness is the editor's smoothing function. The ramp testing was all done with 0 smoothing, but just to see what would happen I also did a couple of import tests with smoothing values of 1.0 and 2.0. It definitely doesn't do what I would expect it to do. I would expect it to round off the edges of the top plateau, and round off the internal edges between the ramp and the steep sides up to the plateau.
Instead, what it does is only round off
one edge of the plateau, and only round off
the opposite internal edge between ramp and sides. The other two relevant edges, one edge of the plateau and the ramp-to-side internal edge opposite it, are not smoothed at all
and remain angular.
And_they_call_this_smoothing.jpg
Given this behaviour it is no wonder I've found that the map "smoothing" modifier tends to make a mess of things. I wouldn't trust is as far as I could throw it. It's clearly going to be better to import terrain with a fine resolution (good elevation tables) and a smoothing value of 0, then do any minor route smoothing manually.
