built_in.md

Built-In Compositors

Built-in compositors are configured by enum name in compositing_method:

{
  "compositing_method": "FIRST_VALID"
}

FIRST_VALID

Selects the first non-nodata value for each pixel/band from items in group order. This is the default and works well for most mosaicking workflows.

MEAN

Computes the per-pixel mean across all valid (non-nodata) item values.

Requires nodata_value to be known for the band set.

MEDIAN

Computes the per-pixel median across all valid (non-nodata) item values.

Requires nodata_value to be known for the band set.

SPATIAL_MOSAIC_TEMPORAL_STACK

Builds a (C, T, H, W) raster by:

1. Spatially compositing items with first-valid logic at each timestep.
2. Stacking the union of timesteps across all items along T.
3. Clipping timesteps to the window request time range.

This is typically used with space_mode: "SINGLE_COMPOSITE" for multi-temporal products.

Requires nodata_value to be known and item rasters to carry timestamps.

Temporal Reducers

TEMPORAL_MEAN, TEMPORAL_MAX, and TEMPORAL_MIN first build a SPATIAL_MOSAIC_TEMPORAL_STACK and then reduce along T to a single timestep.

Requires nodata_value to be known.