A mosaic is a temporal composite: instead of showing one acquisition, the platform combines every scene that passes your filters into a single, cleaner image. It’s the tool of choice when single scenes are too cloudy, too partial or too noisy.
Building a mosaic #
- In Filter Imagery, set your date range and metadata filters as usual.
- Under Optimization, enable Mosaic.
- Choose the Aggregation Method — how overlapping pixels are combined (median is the safe default; mean smooths more; minimum favors dark/clear pixels). The methods offered depend on the instrument.
- Choose the Type:
Normal — a straight composite of everything that passed the filters.
Cloudless — picks cloud-free pixels across dates to minimize cloud in the final image.
Bare-Earth — favors bare-ground pixels, cutting through vegetation cover as much as the archive allows; the geology-first option. - Click Apply & Visualize — the composite renders directly on the Globe.
Mosaic vs Big Areas #
Don’t confuse the two Optimization options: Big Areas merges tiles from the same date into one spatially complete image; Mosaic combines scenes across dates into one temporally aggregated image. They solve different problems and can be relevant to the same Area.
Refining a mosaic from the run card #
The composite’s run card lists the Images actually used to build it, grouped by date with their cloud chips. If one bad acquisition is polluting the result, remove it with the ✕ (Remove and re-run) action — the mosaic rebuilds without it. That’s usually faster than fighting the filters.
Good to know #
- Mosaics take longer to compute than single scenes — the platform is processing every contributing acquisition.
- A composite has no single acquisition date; the run card shows the date range it was built from. Keep that in mind when you interpret change.
- For mineral mapping, try Bare-Earth over your dry season first — it usually beats hand-picking individual scenes.