There has already been a suggestion that the presets be expanded with categories (Horizon Presets - ? which I agree with) but I think that there is the opportunity to develop something with a bit more subtle realism;
- Set the ground
- This would let you set the biome and have options for bump (hills, dunes, waves), gloss (sand, grass, water) and colour (greens for planes and trees, blues for seas, yellows for deserts, greys for neutrals)...
- It would also let you define the horizon position for where the ground touches the sky; this could be set to -100% so that objects could be shown floating in space with the sky wrapping round and +100% where you were inside a sphere. (I think that this should be a curve rather than a straight-line progression between the two extremes.)
(*Note this is independent of the 'ground plane' or 'shadow catcher' feature request.)
- Set the horizon silhouette
- This would be a cut-out that shaped how the ground plane met the horizon (none for the middle of an ocean, spiky for in a forest, blocky for a city, rugged for mountains...) This would have to wrap around the whole horizon, so would have to be really long. A cool utility would be to define on a pie what various segments were. (You would also need to set the rotation and be able to link it to the skybox rotation)
- You could set the scale (height), haze (how sharp the silhouette is), and fade (how much the bottom of the silhouette blends with the ground plane colour at -100% or with the sky horizon at +100%.)
- For ease of use a utility/option to create a new silhouette from the skybox would be useful (or an option to use the inverted skybox alpha channel as one).
- Set the skybox
- This would be the current "horizon" preset, except that it would rotate slightly with movement, making it look like it was set in front of the silhouette. The degree of movement could be increased to make it look closer