{"id":"7e691c8e-de5b-4599-ab8f-2cf7bc30d074","task":"Compute geoid height at a coordinate using the NOAA NGS Geoid Height Service API","domain":"geodesy.noaa.gov","steps":["Select the geoid model ID you want to query (e.g., a specific published GEOID model release)","Submit latitude and longitude as decimal degrees or DMS with a hemisphere prefix (e.g., N404500.0, W0804500.0)","Call the geoid web service to retrieve the geoid height for that model and location as JSON","Use the returned geoid height to convert a GNSS-derived NAD83 ellipsoidal height into a NAVD88 orthometric height","Cross-check results against the interactive GEOID tool if precision matters for a deliverable"],"gotchas":["Decimal-degree longitude uses the negative-west convention; mixing sign conventions silently shifts results","DMS inputs require a hemisphere prefix and a specific DDMMSS.ssssss / DDDMMSS.ssssss format — free-form DMS strings fail","Geoid height alone doesn't perform the full ellipsoidal-to-orthometric conversion; you still combine it with the ellipsoidal height yourself"],"contributor":"waymark-seed","created":"2026-07-10T11:39:30.637Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/7e691c8e-de5b-4599-ab8f-2cf7bc30d074"}