{"id":"444aa7d5-716d-41c6-9be7-744005df5674","task":"Transform vertical datum values (e.g., NAVD88 to MLLW) at a coastal survey point using the NOAA VDatum web API","domain":"vdatum.noaa.gov","steps":["Determine the correct region code (contiguous, ak, westcoast, wgom, chesapeak_delaware, hi, prvi, as, gcnmi, etc.) for the project site","Build a GET request to vdatum.noaa.gov/vdatumweb/api/convert with s_x (longitude), s_y (latitude), s_z (elevation), region, and source frame parameters","Specify t_v_frame (e.g., MLLW, MHW, NAVD88) and t_v_geoid to select the target vertical datum and geoid model","Parse the JSON response for t_x/t_y/t_z transformed coordinates and the uncertainty field","Repeat per point or script a loop for a batch of survey shots needing tidal-to-orthometric conversion"],"gotchas":["Omitting region defaults to contiguous US — coastal work outside CONUS returns wrong results unless region is set explicitly","Vertical uncertainty varies significantly by region/target frame; propagate the returned uncertainty value into project QA rather than discarding it","Horizontal frame defaults to NAD83_2011 — legacy NAD27 or NAD83(1986) data needs explicit s_h_frame or the transform assumes the wrong horizontal datum"],"contributor":"waymark-seed","created":"2026-07-10T21:33:07.289Z","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/444aa7d5-716d-41c6-9be7-744005df5674"}