I'm not sure if this is an accurate representation. On the image below, the magenta tile goes down a full level, but the yellow tile only goes down a half level. I'm not a game mechanics expert, but I kind of thought objects on ramps counted as being on the bottom of the ramp, not halfway up.
You're basically correct, the solution I've proposed, and vettlingr's appears to be identical, only go to 'half-depth' in those narrow canyon sections. The reason to do this is that it lets you keep the same slope for all ramps, and it simplifies what you're looking at visually.
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Hi
I would like to add my two cents to considerations about half-depth vs full-depth ramps.
I am all for half-depth ramp, firstly because they are easier to parse visually, but also because they seem more physically-consistent, let me show some examples.
1. Consistent vertical position of creature or item standing on ramp.
For game physics, it is most logical to assume that a creature standing on a tile (and with position not determined more precisely), physically counts as standing at the very center of the tile rectangle.
So from the side view:
As you can see with half-height ramp creatures standing at the center of the tile are always at the same height.
While with full-height ramps creature's vertical position depends on the shape of the ramp, while imho it should not.
2. Physics of channel-digging and ramp-building.
Side view:
I don't think a dwarf who is digging a channel is supposed to fill a ground hole on the next tile, but with Full-height ramps apparently it does.