It does seem like most other games just use one type of grass to populate the world with, and they seem visually fine. We don’t necessarily have to limit ourselves to what most other games do though, perhaps Thrive will lead the way in realistic lawn visualization technology… if the performance is available.
Correct, depending on the scale the world is viewed at, the amount of large things like trees will have a similar amount of objects on screen rendered at a similar density to smaller scales viewing smaller things like grass. The LOD management system will operate the same at both scales when the detail is similar.
For example, compare the density of plants per unit of screen area of these images of grassland and a forest: (They seem similar at these scales, with the density increasing similarly as you approach the horizon)
This image from that great quora post shows the separate plants better, though it has a bit less density compared to the other images due to the (presumably) smaller scale:
More visual variation can also be given to the higher level of detail models of the plants for those that are close enough to use more detail. It shouldn’t be a performance issue have many more variations for each type of plant for the local area around the camera. They would still need to be approximately visually continuous with the low detail models used when viewing at farther distances, as those could be shared by multiple different variations.
For example, the previous picture with the plants having various shades of purple flowers could have a single low detail billboard with a single average shade of purple that is used across all of that same type of plant. If there is enough performance then perhaps more billboards could be created for the different variants, like a different dark purple and light purple flower billboard.
With the plants and billboards being generated at run time by the game, there should be a significant amount of flexibility that the system has to adapt to the performance budget of the player’s computer.
That should be possible; it could be created using the billboard system by just creating one flat plane billboard from above, then applying that texture to the ground texture. Mixing multiple plant species/different objects should also not be difficult to extend the system with. This might also include other objects like rocks (Are there other objects to consider here? Maybe sticks?).
I wonder, would the density of plants be consistently lower earlier on in the timeline across most/all land biomes? That could be helpful if earlier stages/editor cycles are less dense than later on, if it takes some time for either the plants to evolve enough to become denser or if the environment takes a significant amount of time to be changed to support denser plant coverage?
Also, I know grass didn’t technically exist yet, but those Ordovician plants look quite close to grass to me at this scale.