COALA Areas

A fundamental system of how COALA works are the "areas" (also known as chunks or tiles). These areas are indexable through the zoom level shown in the image below:

Hierarchy Order

In play mode, each area is created as its own object. All objects that are spawned within that area are collected under this object. Take a look at the World Outliner in play mode to see the hierarchy of it.

CoalaAreaActor_area (the name also includes the tile index)

- cells (basically the terrain)
  - CoalaMeshActor cells
- waters (all water shapes are grouped here)
  - CoalaMeshActor water
- buildings (contains all buildings - depending on your configuration the meshes could be merged or independent for each building)
  - - floors (only floor part of building/s)
    - walls (only wall part of building/s)
    - roofs (only roof part of building/s)

pois (all Points Of Interests that exist in that area are listed here - not the ones from the back-end, but your configured POI prefabs)
streets (contains all street types/categories)
- - CoalaMeshActor street

- decorations (all decorations that have been spawned in that area)
  - StaticMeshActor decoration

Scene View Area Details

Buffered areas

Sometimes it makes sense to buffer/load additional areas around the players area, so that if a requests takes longer than usual, there are no issues.

In top-down view the scene could look like this, with the player always in the center of the world:

Hint: You can increase/decrease the area buffer in the BP_Coala child in the Setup section.

Cells / Terrain

One important part of the COALA area is the terrain. It is divided into cells and each cell is filled with the context information you defined at the back-end. This plug-in also provides functionality to get context information for a specific cell or GPS position/location.

Currently, an area is divided into 45*45 cells: That makes a total of 2025. Hint: Visit the Back-End Visualization tool page for more information.

Elevation

Additionally, each cell has information about its real world height (in meters). This way you can create an elevated, three dimensional terrain instead of a flat representation of the world.

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