Light Uniformity Grid Checker

Audit measured light-grid population variability and minimum/mean plus low-light area using physical cell weights; no lamp-layout optimization or universal crop threshold.

Description

Light uniformity depends on both measured intensity and the area represented by each sample.

Light uniformity depends on both measured intensity and the area represented by each sample. Unequal cells require area weighting rather than an unweighted grid average.^[1]

Audit measured light-grid population variability and minimum/mean plus low-light area using physical cell weights; no lamp-layout optimization or universal crop threshold.

When to use Light Uniformity Grid Checker

Use this tool to audit measured light-grid population variability and minimum/mean plus low-light area using physical cell weights; no lamp-layout optimization or universal crop threshold.

Prepare the plant, nutrient, light or scheduling measurements for the intended crop and period. Keep paired records aligned and confirm units and supplied target values.

How to use Light Uniformity Grid Checker and understand its results

Prepare the plant, nutrient, light or scheduling measurements for the intended crop and period. Keep paired records aligned and confirm units and supplied target values.
Enter ppfdGrid, cellAreasM2, callerMinimumToMeanRatio, callerMinimumPpfd using the field table and calculation rules, then run the tool.
Read areaWeightedMeanPpfd, areaWeightedCv, minimumToMeanRatio, areaFractionBelowCallerPpfd, meetsCallerUniformity. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
ppfdGrid	Ppfd grid	list of list of number	Required
cellAreasM2	Cell areas m2	list of list of number	Required
callerMinimumToMeanRatio	Caller minimum to mean ratio	number	Required
callerMinimumPpfd	Caller minimum ppfd	number	Required

Enter matching nonempty rectangular PPFD and positive-area grids, nonnegative minimum PPFD and ratio criterion in [0,1]. Require positive mean light. Return weighted mean/CV, minimum-to-mean ratio, area strictly below the PPFD threshold and inclusive ratio-compliance flag.

weighted mean=Σarea × PPFD/Σarea; CV=sqrt(weighted population variance)/mean

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
areaWeightedMeanPpfd	Area weighted mean ppfd	number
areaWeightedCv	Area weighted cv	number
minimumToMeanRatio	Minimum to mean ratio	number
areaFractionBelowCallerPpfd	Area fraction below caller ppfd	number
meetsCallerUniformity	Meets caller uniformity	boolean

json

{
  "input": {
    "ppfdGrid": [
      [
        100,
        200
      ],
      [
        300,
        400
      ]
    ],
    "cellAreasM2": [
      [
        1,
        1
      ],
      [
        1,
        1
      ]
    ],
    "callerMinimumToMeanRatio": 0.3,
    "callerMinimumPpfd": 150
  },
  "output": {
    "areaWeightedMeanPpfd": 250,
    "areaWeightedCv": 0.4472135954999579,
    "minimumToMeanRatio": 0.4,
    "areaFractionBelowCallerPpfd": 0.25,
    "meetsCallerUniformity": true
  }
}

Limitations and assumptions

Sampling and cell areas are supplied. The tool does not optimize lamp placement or supply crop thresholds.

Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Matrices are limited to 128 rows and 128 entries per row; other numeric lists are limited to 100,000 entries. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Daily Light Integral MOL M2 Day: Integrate measured time-varying PPFD by trapezoids into observed daily photon dose; unobserved hours are not silently filled and a constant PPFD-to-DLI alias is excluded. For a complementary task, use LED Cost Per DLI Delivered: Compare electrical and allocated fixture costs per delivered canopy photon mole and per DLI unit using supplied efficacy/delivery; canopy area distinguishes total photons from areal dose.

References

Light Uniformity Grid Checker — tool.io

Similar or alternative tools

Daily Light Integral MOL M2 Day
Integrate measured time-varying PPFD by trapezoids into observed daily photon dose; unobserved hours are not silently filled and a constant PPFD-to-DLI alias is excluded.
LED Cost Per DLI Delivered
Compare electrical and allocated fixture costs per delivered canopy photon mole and per DLI unit using supplied efficacy/delivery; canopy area distinguishes total photons from areal dose.