emem-recall-polygon

emem-recall-polygon

This skill calls /v1/recall_polygon to fetch facts inside an arbitrary polygon. The responder samples every cell64 whose centre falls inside the polygon (cap: 1024 cells per request, max_cells, default 64), recalls the requested band(s) at each, and returns a structured response with a per-cell receipt for verification.

When to invoke

The user defines a region rather than a point:

• "What's the average NDVI inside this watershed: [coords]?"
• "Show me precipitation across the area bounded by …"
• "Recall elevation across this admin boundary."
• The user pastes GeoJSON or a list of [lng, lat] pairs.

If the user just wants a single cell, use emem-locate-and-recall. If they want a similar-cells list rather than a polygon, use emem-find-similar.

How to invoke

The polygon is a closed ring: [[lng0, lat0], [lng1, lat1], …, [lng0, lat0]]. Coordinates are WGS-84 decimal degrees, longitude first (GeoJSON convention).

curl -sf -X POST https://emem.dev/v1/recall_polygon \
  -H 'content-type: application/json' \
  -d '{
    "polygon": [
      [77.55, 12.95],
      [77.65, 12.95],
      [77.65, 13.05],
      [77.55, 13.05],
      [77.55, 12.95]
    ],
    "bands": ["indices.ndvi", "weather.precipitation_mm"]
  }' | jq '{
    cells_returned: (.by_cell | length),
    facts_total:    (.by_cell | to_entries | map(.value.facts | length) | add),
    area_km2:       .area_km2
  }'

Picking the band

If the user asked about precipitation, use weather.precipitation_mm (current 24 h) or era5.precip (1940→ present hourly). If they asked about vegetation, use indices.ndvi (computed live from S2) or modis.ndvi_mean (16-day MODIS composite, larger pixels but global). If they asked about elevation, use copdem30m.elevation_mean (30 m, terrestrial only; gmrt.topobathy_mean for ocean depths). Full band list at https://emem.dev/v1/bands.

Computing aggregates

The response is per-cell facts; the agent does the rollup: