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Because every HEALPix cell covers the same surface area, the resulting spectrum carries none of the latitude-dependent area\nweighting that a lon/lat grid would impose — supporting the claim by construction. The spectrum shows the expected monotonic power-law fall-off with\nspatial frequency, the signature of a natural surface-reflectance field." } ], "https://w3id.org/sciencelive/o/terms/hasConfidenceLevel": [ { "@id": "https://w3id.org/sciencelive/o/terms/Moderate" } ], "https://w3id.org/sciencelive/o/terms/hasEvidenceDescription": [ { "@value": "Configuration and result recorded in results/powerspectrum.json:\n- scene S2A_22WEV_20190723, band B04 (red, 10 m), 256×256 px window (~2.6 km)\n- equal-area HEALPix at depth 18 (nside = 262144), ellipsoid = WGS84\n- field sampled at equal-area cell centres, then radially-averaged isotropic power spectrum computed with healpix-analyse `ps`\n- the spectrum (results/powerspectrum.png) falls off monotonically with spatial frequency on a log–log axis (power-law behaviour), with no latitude-dependent amplitude term, because the cells are equal-area by construction.\n\nGithub repository: https://github.com/annefou/healpix-analyse-s2-powerspectrum" } ], "https://w3id.org/sciencelive/o/terms/hasLimitationsDescription": [ { "@value": "The repo demonstrates the equal-area pipeline rather than quantifying the lon/lat bias it avoids: no side-by-side lon/lat baseline spectrum is computed here, so\nthe bias magnitude is argued by construction, not measured. Single scene, single band, single date; no atmospheric, cloud, or coastal effects; generalisation to other sensors and to a controlled multi-latitude comparison is left to follow-up." } ], "https://w3id.org/sciencelive/o/terms/hasOutcomeRepository": [ { "@id": "https://doi.org/10.5281/zenodo.21000097" } ], "https://w3id.org/sciencelive/o/terms/hasValidationStatus": [ { "@id": "https://w3id.org/sciencelive/o/terms/Validated" } ], "https://w3id.org/sciencelive/o/terms/isOutcomeOf": [ { "@id": "https://w3id.org/sciencelive/np/RALm0wEYfKg4NKqTwY33LsGKIR7UH0Ut2IgYvX8uEeJMM/s2-equal-area-healpix-study" } ] } ] }, { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/provenance", "@graph": [ { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/assertion", "http://www.w3.org/ns/prov#wasAttributedTo": [ { "@id": "https://orcid.org/0000-0002-1784-2920" } ] } ] }, { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/pubinfo", "@graph": [ { "@id": "https://orcid.org/0000-0002-1784-2920", "http://xmlns.com/foaf/0.1/name": [ { "@value": "Anne Fouilloux" } ] }, { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs", "http://purl.org/dc/terms/created": [ { "@value": "2026-06-28T15:46:05.059Z", "@type": "http://www.w3.org/2001/XMLSchema#dateTime" } ], "http://purl.org/dc/terms/creator": [ { "@id": "https://orcid.org/0000-0002-1784-2920" } ], "http://purl.org/dc/terms/license": [ { "@id": "https://creativecommons.org/licenses/by/4.0/" } ], "http://purl.org/nanopub/x/introduces": [ { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/s2-equal-area-healpix-outcome" } ], "http://purl.org/nanopub/x/wasCreatedAt": [ { "@id": "https://platform.sciencelive4all.org" } ], "http://www.w3.org/2000/01/rdf-schema#label": [ { "@value": "Sentinel-2 equal-area HEALPix power-spectrum outcome" } ], "https://w3id.org/np/o/ntemplate/wasCreatedFromTemplate": [ { "@id": "https://w3id.org/np/RA2zljn0Nw9SadppOyxZoh-_Rxosslrq-vYG-p9SttnJE" } ] }, { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/sig", "http://purl.org/nanopub/x/hasAlgorithm": [ { "@value": "RSA" } ], "http://purl.org/nanopub/x/hasPublicKey": [ { "@value": "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" } ], "http://purl.org/nanopub/x/hasSignature": [ { "@value": "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" } ], "http://purl.org/nanopub/x/hasSignatureTarget": [ { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs" } ], "http://purl.org/nanopub/x/signedBy": [ { "@id": "https://orcid.org/0000-0002-1784-2920" } ] } ] }, { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/Head", "@graph": [ { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs", "http://www.nanopub.org/nschema#hasAssertion": [ { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/assertion" } ], "http://www.nanopub.org/nschema#hasProvenance": [ { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/provenance" } ], "http://www.nanopub.org/nschema#hasPublicationInfo": [ { "@id": "https://w3id.org/sciencelive/np/RAW7XIpK-5SmVOoRoVPl-w_xjr9cqgM8xRRIKQ575RVXs/pubinfo" } ], "@type": [ "http://www.nanopub.org/nschema#Nanopublication" ] } ] } ]