GREENWORLD SECTOR-7 // METRICS // VC-MET-002
ALL SYSTEMS NOMINAL · —
METRICS · PLANT VITALITY & PHYSIOLOGY

NDVI (Normalized Diff. Vegetation Index)

VC-MET-002 — the canopy greenness ratio derived from red and near-infrared reflectance, the leading spectral indicator of photosynthetic leaf area and the dominant sub-signal feeding the Canopy Vitality Index.

Metric ID VC-MET-002 Category Plant Vitality & Physiology Unit index −1…1 Type Derived Source Spectral Canopy Array Sampling 15 min Owner Metrology & Telemetry Standards Rev C · Effective 2089-06-01
Current 0.81 Nominal 0.72–0.90 15-min cadence Spectral Canopy Array

Definition

NDVI is a dimensionless ratio in the range −1…1 expressing the contrast between near-infrared (NIR, strongly reflected by healthy mesophyll) and red (strongly absorbed by chlorophyll) canopy reflectance. High positive values indicate dense, photosynthetically active foliage; values near zero indicate bare substrate, structure, or chlorotic tissue; negative values indicate water or specular surfaces. At GreenWorld Sector-7 NDVI is computed per bench cell from calibrated hyperspectral passes of the Spectral Canopy Array and reported as the masked-canopy median.

Why it matters

NDVI is the earliest spatial read on declining leaf area and chlorophyll density — it falls before turgor or gas-exchange channels register a problem, and it localizes decline to a specific bench or sphere cluster that point sensors cannot resolve. It carries the largest single weight (0.35) in the Canopy Vitality Index (VC-MET-001), and CHLORA uses its spatial gradient to steer Pollinator Drone Swarm imaging and to prioritize manual inspection on the Operations Dashboard.

Formula

NDVI is the normalized band difference of the atmospherically and illumination-corrected reflectance, masked to live canopy:

NDVI = (ρ_NIR − ρ_RED) / (ρ_NIR + ρ_RED)

bands (Spectral Canopy Array):
  ρ_RED  = reflectance at 665 nm  (10 nm FWHM)
  ρ_NIR  = reflectance at 842 nm  (20 nm FWHM)

processing chain per 15-min pass:
  1. dark/flat-field + reference-panel calibration (white tile, 99%)
  2. illumination normalization to PAR reference
  3. soil/structure mask: exclude pixels where NDVI < 0.20
  4. report = median(NDVI) over masked canopy pixels of the cell

Reported to 0.01. Forward-filled between passes; flagged STALE
after 2 missed passes (> 30 min).

Inputs

ChannelBand / QuantityReference BandSource
ρ_REDRed reflectance, 665 nm0.03 → 0.12Spectral Canopy Array
ρ_NIRNIR reflectance, 842 nm0.45 → 0.70Spectral Canopy Array
Cal panel99% white reference tileper-passSpectral Canopy Array
PAR refIncident PAR normalization200 → 900 µmol·m⁻²·s⁻¹PhytoSense Mesh

Units & Scale

Dimensionless, −1…1, reported to two decimal places. Spatially aggregated as the masked-canopy median (not mean) to suppress edge and structure artefacts; facility NDVI is the leaf-area-weighted mean of cell medians. Confidence degrades when masked-pixel fraction drops below 60% of the cell or when illumination normalization residual exceeds 8%.

Sampling & Source

Thresholds

Nominal · 0.72–0.90

OK

Dense, healthy canopy. No action.

Warning · < 0.65

WARN

Greenness loss; CHLORA advisory, inspect cell within one cycle.

Critical · < 0.55

CRIT

Severe canopy loss; auto-dispatch against the cell.

Hysteresis & masking. Recovery from WARN requires NDVI ≥ 0.70 sustained over three consecutive passes; CRIT clears at ≥ 0.62 over four passes. A sudden NDVI collapse coincident with a masked-pixel-fraction drop is treated as an imaging/occlusion fault, not a plant event, and routed to Array maintenance rather than cultivation dispatch.

Recent Trend

Facility leaf-area-weighted NDVI, last 14 passes:

NDVI · 14-pass trend (current 0.81)

Interpretation Guidance

NDVI BandReadingLikely DriverAction
0.85–0.90Peak leaf areaFull closed canopy at optimumMaintain; log as reference.
0.72–0.84HealthyNormal phenological variationNone; normal range.
0.65–0.71Soft declineEarly chlorosis or canopy thinningCross-check Fv/Fm (VC-MET-003) & senescence (VC-MET-011).
0.55–0.64WARN stressLeaf loss, N deficiency, or water stressCultivation review; inspect EC & canopy temp.
< 0.55CRIT failingMajor dieback or sensor occlusionAuto-dispatch; verify mask before isolation.
VC-MET-001

Canopy Vitality Index

Composite NDVI feeds at 35% weight.

 VC-MET-003

Fv/Fm Fluorescence

Photochemical confirmation of greenness loss.

 VC-MET-010

Leaf Area Index

Structural driver of NDVI saturation.

 VC-MET-011

Senescence Fraction

Lagging confirmation of canopy decline.

 VC-MET-012

Anthocyanin Reflectance

Pigment stress signal from the same Array.

 VC-MET-102

VPD

Environmental driver of greenness decline.

Related SOPs