Vessel Tracking

H3 density

H3 density is a spatial summary of AIS positions. H3 is a hierarchical hexagonal index: each latitude and longitude is assigned to a cell, and Overwatch stores the cell identifier as h3_index. The repository computes it in application code with h3-js at resolution 8 because the project's Postgres H3 extension is unavailable. The density dashboard groups the daily vessel_density_h3_daily data by vessel type for its rollup, showing H3 cells, positions, and unique vessels. Its map requests one vessel type and day, converts returned H3 cells into polygon boundaries, and shades them by position count. The result shows where tracked activity is concentrated; it does not identify cargo or prove a vessel remained in one cell. Why it matters for grain flows: H3 density helps locate vessel concentrations around export ports and approaches before analysts inspect individual visits.

See how this fits into the platform: Axiom Overwatch · pricing