Add Area Seeder
Area seeders are surfaces that are projected onto the slope surface and used to initiate falling rocks. The rock locations are generated with a Uniform distribution along the surface area of the plane seeder (i.e., there is an equal probability that the rock will fall from any point on the plane).
To add an area seeder:
Select: Seeders > Add Area Seeder 
The following dialog will pop up:
In this dialog, you can assign a specific seeder property to the area seeder. You can also view/make changes to the seeder property by clicking on the pencil icon next to the property dropdown menu.
The Elevation (Z Value) section is used to define whether to have the plane seeder either:
- On Surface,
- Height Above Surface,
- Absolute Value, or
- Custom
To define the location of the area seeder, select the Add Points on Viewport to begin drawing the area seeder in any of the viewports.
The Add Area Seeder dialog will pop up. You can now start drawing the area seeder in the viewport. Below shows an example of an area seeder being drawn:
After drawing the area, select OK. You can now change the option of the Elevation to Height above Surface, Absolute Value, or Custom. This will take the defined area and orient it according to inputs.