What is an Abiotic Factor?
Did you ever hear about this term before?
Definition
"An abiotic factor is a non-living part of an ecosystem that shapes its environment. In a terrestrial ecosystem, examples might include temperature, light, and water. In a marine ecosystem, abiotic factors would include salinity and ocean currents. Abiotic and biotic factors work together to create a unique ecosystem."
Source : National Geographic
In other words, the abiotic factors are all-terrain related features that can influence your scatter-system(s), they are essential to give credibility and realism to your virtual world. Especially if you are scattering a natural landscape scene!
Elevation
Mask based on your terrain elevation
Elevation Factor
The abiotic elevation feature will remove instances above or below a certain altitude threshold. You can control both minimal/maximal transitions with their density/scale influence on the scatter.
Use-case
When scattering a forest that covers large areas of your landscape, you can assign elevation rules such as fewer & smaller trees located at higher altitudes. In the real world depending on the oxygen level the probability of having various tree species differs..
Elevation Space
The threshold value can be represented as a percentage unit, based on the minimal/maximal vertex location of your surface mesh found, or in an altitude unit, where the altitude is sampled from the local or global space.
If you'd like your altitude effect to stay consistent across many surfaces, we advise you to choose the global space method with the altitude unit method.
Slope
Mask based on your terrain slope angle
Slope Factor
The abiotic slope feature will remove instances above or below a defined slope threshold. You can control minimal/maximal transitions and their density/scale influence.
Use-case
Some plant species will not be able to grow on steep terrain, so adding a
slope rule in your scatter is an essential tool to have at your disposal.
It can also be quite handy to define flat scattering areas for scattering
cities or villages for example.
Orientation
Mask based on your terrain slope orientation
Orientation Factor
The orientation border feature will remove instances depending on how similarly aligned the instances normal are compared to a chosen direction.
Use-case
Add moss on rocks, and distribute plant species on slopes that receive more/less sun.
Orientation Space
Here on the left, we can see an orientation factor based on the local surface space, on the right, based on global world space.
Curvature
Mask based on your terrain curvature
Curvature Factor
The abiotic curvature feature will remove instances depending on the concavity/convexity of your surface(s).
Note that this feature might be too sensitive for too noisy terrains. As the curvature data is calculated in real-time, you might experience slowdowns when using high-poly surfaces.
Border
Mask your scatter near your terrain borders
Border Factor
The abiotic border feature will remove instances near the border of your surface's boundary edges. You are able to control the distance/transition distance.
Use-case
When scattering large clumps of grass, it can be difficult to achieve clean delimitation near borders, use this feature to remove the clumps of grass whose origin stands too close to the boundaries of your surfaces.