crop-type-map

○unverified

Label-free (unsupervised) per-field crop-type mapping from a multi-index Sentinel-2 phenology SIGNATURE. For an AOI covered by a Fields of the World boundary set, compute an NDVI + EVI + NDRE time series, fit harmonic curves to each index to extract its amplitude (how much the crop greens/matures) and phase (WHEN it peaks — the crop calendar), stack those (index × harmonic) features into a per-pixel signature, and cluster the signature with k-means into crop GROUPS. Per-field majority vote over the cluster raster gives one crop-group label per field. The per-field group table is the primary product; the multi-index stack and harmonic amplitude/phase rasters are the inspectable "show your work" layers. This is the honest FIRST version: it needs NO training labels — it discovers crop groups from the phenology structure itself. The clusters are anonymous ("group 0/1/2…") until named; where USDA CDL (boryan-2011) covers the AOI, the optional validation step names each cluster by its majority CDL class and reports cluster↔CDL agreement. The SUPERVISED path (a CDL-trained classifier that emits named crop classes directly, no post-hoc naming) is the v2 — see the NOTE on compute/crop_cluster. This extends crop-monitoring (single-index NDVI vigor/phenology) with two additions: a multi-index signature (NDRE separates canopy N / structure that NDVI alone misses) and an unsupervised clustering head that turns the signature into a discrete crop-group layer.