DSF Raster Data RFC

2/20/2012 - Update 2/19/2011 - Initial Revision

Status: implemented in X-Plane 10.0

This is a proposal for raster data to be directly encodeable in a DSF file.

Traditionally, per-entity parameters are encoded on the various geometric parts of a DSF, e.g. triangle vertices, object,s etc.

However, sometimes it may be desirable to encode low frequency data - in this case:
 * Nearby building blocks like objects or roads would all have the same data (or data that could have been calculated by interpolation); per-block storage is not efficient.
 * If the data is spatial in nature, separate blocks would have the same data, e.g. two objects next to a road would all have the same value; per-block storage means duplication.

This proposal would allow the DSF to contain one or more raster layers that would imply a low-frequency data set 'over' the entire DSF.

Proposed basic implementation:
 * Each raster layer would live in its own one-plane 16-bit point pool. A corresponding scaling atom would help 'decode' the data.
 * A string table atom in the definitions section would provide a master key from string-based raster layer definitions to the particular pool providing the data, using an in-order scheme.
 * No new commands are introduced.