{"age_s":0,"band":"indices.ndvi","band_metadata":{"description":"Three optical-index scalars derived from Sentinel-2 L2A: NDVI, NDRE, NDMI. The most-pulled vegetation surface — these are what algorithms like `flood_risk@2`, `crop_stress@1`, and `irrigation_demand@1` compose.","dimension_description":"Normalised Difference Vegetation Index","dimension_index":0,"formula":"NDVI = (B08 − B04) / (B08 + B04), each band first scaled to reflectance as DN * 1e-4 in f64, applied per band before the ratio. Folding the scaling through the ratio is algebraically equal but can differ in the last bits.","inherited_from_cube_band":"indices","interpretation":"NDVI < 0 = water / snow; 0 – 0.2 = bare soil / urban; 0.2 – 0.5 = sparse / stressed vegetation; 0.5 – 0.8 = healthy crops / shrub; > 0.8 = dense closed canopy. NDMI tracks canopy water content (negative = dry, positive = moist). NDRE is more sensitive to chlorophyll than NDVI and saturates later — preferred for in-season nitrogen monitoring.","pitfalls":"Read `surface_class` on the fact before the value. It carries the per-pixel Sentinel-2 SCL class the responder actually probed at this cell (`scl`, `label`, `vegetation_valid`) and answers a question `confidence` does not: confidence scores radiometric cleanliness, so a snow-covered field in January is a clean pixel and scores 0.95 while the NDVI on it measures snow, not vegetation. `vegetation_valid: false` (snow, water, shadow) means the number is real but is not a vegetation reading. Prefer this over the scene-level `weather.cloud_cover` / `cloud_pct` proxies: those describe the whole scene, `surface_class` describes this pixel. Absent when the SCL band could not be read, in which case confidence falls back to scene-level cloud cover and the scene-level proxies are all there is. NDVI saturates above ~0.85 (use NDRE / `geotessera` for dense canopies).","provenance":{"class":"deterministic_index","deterministic":true,"tamper_evidence":"recomputable_from_source","trust_rank":4},"references":"Tucker 1979 (NDVI); Gitelson & Merzlyak 1994 (NDRE); Gao 1996 (NDMI / NDWI); Xu 2006 (MNDWI = (B03-B11)/(B03+B11)); Key & Benson 2006 (NBR = (B08-B12)/(B08+B12)); Hall et al. 1995 (NDSI = (B03-B11)/(B03+B11)); Zha et al. 2003 (NDBI = (B11-B08)/(B11+B08)); Rikimaru et al. 2002 (BSI = ((B11+B04)-(B08+B02))/((B11+B04)+(B08+B02))); Hardisky et al. 1983 (NDWI_Gao = (B03-B08)/(B03+B08), the leaf-water-content form used by the algal-bloom water gate)","units":"unitless [-1, +1]","value_range":[-1.0,1.0]},"captured_at":"2026-10-04T13:47:11.025000Z","cell64":"defi.zb3db.wuma.zb80e","cell_dedupe_m":10,"cid_v1":"bafkr4ib6ksxaepu4evwycvumyspaee3gpss66txh5pywyrx6m5ov5xnfym","confidence":0.949999988079071,"data_resolution_m":10,"derivation_fn_key":"sentinel2_l2a_indices_ndvi@1","fact_cid":"hzkk4ar6tqsw3akwrtcj4aqtmz6kl32o47v7c3cg7ztv2xw5uxbq","kind":"primary","lat":-3.2027777777778,"lon":-52.205833333333,"materialize_notes":[{"band":"indices.ndvi","fact_cid":"hzkk4ar6tqsw3akwrtcj4aqtmz6kl32o47v7c3cg7ztv2xw5uxbq","status":"materialized"}],"memory_token":"emem:fact:defi.zb3db.wuma.zb80e:hzkk4ar6tqsw3akwrtcj4aqtmz6kl32o47v7c3cg7ztv2xw5uxbq","next":{"deep_recall":"POST /v1/recall {cell:'defi.zb3db.wuma.zb80e', bands:[…]}","fact_dereference":"GET /v1/facts/{fact_cid}","history":"POST /v1/backfill {cell:'defi.zb3db.wuma.zb80e', band:'<band>', from_unix:…, to_unix:…}","polygon_aggregate":"POST /v1/recall_polygon {place:'<text>', bands:[…], max_cells:9}","verify_offline":"POST /v1/verify_receipt {receipt}"},"resolution_m_input":10,"responder_pubkey_b32":"cfvys4rv62o3kxduhuzlx5bqavbcg5rofrhk56wh5gkeprrkwxaa","served_at":"2026-10-13T22:05:04Z","signed_at":"2026-10-13T22:05:04Z","source":"sentinel_s2_l2a","source_url":"https://sentinel2l2a01.blob.core.windows.net/sentinel2-l2/22/M/CB/2026/10/04/S2C_MSIL2A_20261004T134711_N0513_R024_T22MCB_20261004T184116.SAFE/GRANULE/L2A_T22MCB_A010862_20261004T135222/IMG_DATA/R10m/T22MCB_20261004T134711_B08_10m.tif ; https://sentinel2l2a01.blob.core.windows.net/sentinel2-l2/22/M/CB/2026/10/04/S2C_MSIL2A_20261004T134711_N0513_R024_T22MCB_20261004T184116.SAFE/GRANULE/L2A_T22MCB_A010862_20261004T135222/IMG_DATA/R10m/T22MCB_20261004T134711_B04_10m.tif","sources":[{"captured_at":"2026-10-04T13:47:11.025000Z","cid":null,"hash_sha256_hex":null,"id":"https://sentinel2l2a01.blob.core.windows.net/sentinel2-l2/22/M/CB/2026/10/04/S2C_MSIL2A_20261004T134711_N0513_R024_T22MCB_20261004T184116.SAFE/GRANULE/L2A_T22MCB_A010862_20261004T135222/IMG_DATA/R10m/T22MCB_20261004T134711_B08_10m.tif ; https://sentinel2l2a01.blob.core.windows.net/sentinel2-l2/22/M/CB/2026/10/04/S2C_MSIL2A_20261004T134711_N0513_R024_T22MCB_20261004T184116.SAFE/GRANULE/L2A_T22MCB_A010862_20261004T135222/IMG_DATA/R10m/T22MCB_20261004T134711_B04_10m.tif","scheme":"sentinel_s2_l2a","url":null}],"tslot":20730,"unit":null,"value":0.4553917765709853}