Cesium Native's raster overlays are georeferenced 2D images - perhaps consisting of trillions of pixels or more! - that are draped over the top of a [Tileset](\ref Cesium3DTilesSelection::Tileset). A classic example of a raster overlay is a satellite imagery layer. A `Tileset` can have multiple raster overlays, and they're usually alpha-blended together in a layered fashion. They can also be used for more sophisticated effects, however. For example, a raster overlay could represent a "mask" of where on Earth is land versus water, and that mask used in a custom shader or material to render waves in the water-covered areas.
To add a raster overlay to a `Tileset`, construct an instance of the appropriate class and add it to the [RasterOverlayCollection](\ref Cesium3DTilesSelection::RasterOverlayCollection) returned by [Tileset::getOverlays](\ref Cesium3DTilesSelection::Tileset::getOverlays). See the reference documentation for each overlay for details about how to configure that overlay type.
