https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/Head https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4 http://www.nanopub.org/nschema#hasAssertion https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/assertion https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4 http://www.nanopub.org/nschema#hasProvenance https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/provenance https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4 http://www.nanopub.org/nschema#hasPublicationInfo https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/pubinfo https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4 http://www.w3.org/1999/02/22-rdf-syntax-ns#type http://www.nanopub.org/nschema#Nanopublication https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/assertion https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/healpix-wgs84 http://schema.org/endDate 2026-04-08 https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/healpix-wgs84 http://www.w3.org/1999/02/22-rdf-syntax-ns#type https://w3id.org/sciencelive/o/terms/FORRT-Replication-Outcome https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/healpix-wgs84 http://www.w3.org/2000/01/rdf-schema#label WGS84 Ellipsoid Significantly Affects HEALPix Cell Assignment at Mid and High Latitudes https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/healpix-wgs84 https://w3id.org/sciencelive/o/terms/hasConclusionDescription WGS84 ellipsoid indexing assigns pixels to substantially different HEALPix cells than sphere-based indexing, particularly at mid and high latitudes. At mid-latitudes (+48°), 98% of pixels are assigned to a different cell. This demonstrates that sphere-based HEALPix indexing is unsuitable for European Earth observation data (Copernicus/Sentinel, 45-65°N). https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/healpix-wgs84 https://w3id.org/sciencelive/o/terms/hasConfidenceLevel https://w3id.org/sciencelive/o/terms/HighConfidence https://w3id.org/sciencelive/np/RANLZSWPo1AXNszhQDilv20UB6wM32Gp6WzbUhTCfzUK4/healpix-wgs84 https://w3id.org/sciencelive/o/terms/hasEvidenceDescription ELLIPSOID ANALYSIS (HEALPix depth 9, sphere vs WGS84): | Region | Center lat | Pixels in different cell | Jaccard similarity | |---------------|------------|--------------------------|-------------------| | Equatorial | 0° | 26.6% | 0.9951 | | Mid-latitude | +48° | 98.4% | 0.9844 | | High-latitude | +62° | 90.8% | 0.9868 | | Arctic | +78° | 52.6% | 0.9908 | At mid-latitudes (Mediterranean, +48°), nearly every pixel (98.4%) is assigned to a different HEALPix cell when using sphere vs WGS84 ellipsoid. Polygon coverage Jaccard similarity drops to 0.9844, indicating measurable differences in spatial coverage. 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