TerraGear roadmap
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World Scenery 2.0 has been released. After 2 1/2 years of development, the tool-chain is considered stable. Although WS2.0 will continue to receive updates, and bug fixes, I'd like to start planning for the next major overhaul.
For World Scenery 3.0, flightgear will have a LOD system for the underlying mesh. The good news is, this new system is already in simgear (thanks to Mathias), and has been tested with 'hand stitched' .btg files. So our job, is to update the tools to be able to generate the scenery automatically.
Ideally, we would like to have at least 4 levels of detail.
The highest detail level being identical to WS2.0.
The second level of detail maintains the same elevation mesh, but removes line data from both airports and terrain. Airports are still smoothed, and cut in to the terrain.
The third level of detail is a simplified mesh, with simplified airports (no bezier interpolation) created as landclass polys (runway, taxiway, and grass). To be determined, is how to simplify the landclass polygons. possibly combining a small area landclass with it's neighbor.
Optional fourth level and more LODs would be refinements to the third - lower res mesh, and more landclass combining)
The lowest detail level being a sphere with a global texture.
In the terragear toolchain, there are 3 main directories: Data, Work, and Output. The Work directory structure will be overhauled to handle arbitrary tile sizes. The output directory needs to match what simgear .SPT files expect.
The below table is my first attempt at a work item breakdown. I imagine we'll need to add / remove entries as work progresses.
| Tool | Work item | Progress |
|---|---|---|
| genapts | separate .btg for line data | 
|
| genapts | runway texture atlas |  Pending
|
| genapts | airport as landclass | Pending
|
| hgtchop | support arbitrary tile sizes / directory structure | Pending
|
| hgtfit | support arbitrary tile sizes / directory structure | Pending
|
| hgtfit | port from terra to CGAL mesh simplification (optional / cleanup) | Pending
|
| ogrdecode | support arbitrary tile sizes / directory structure | Pending
|
| tgconstruct | add tile skirts to hide LOD gaps | Pending
|
| tgconstruct | arbitrary tile sizes / directory structure | Pending
|
| tgconstruct | .spt file generation | Pending
|