eulumdat-analysis

Practical photometric calculations on EULUMDAT data.

Part of the eulumdat-* Python ecosystem built on eulumdat-py.
Developed in an ISO 17025 accredited photometry laboratory.

Features

• half_angle — half-angle at half maximum (HAHM) per C-plane, with CubicSpline interpolation
• resample — resample a Ldt to a coarser angular resolution (linear interpolation, ISO 17025 traceable)
• rotate — azimuthal rotation of the intensity matrix by an arbitrary multiple of the angular step
• luminous_flux — total flux in lm/klm by trapezoidal integration (CIE 190 method)
• luminous_flux_range — flux integrated over an arbitrary gamma window [g_min, g_max] in lm/klm
• lorl_computed — LORL in % computed from the intensity matrix
• dff_computed — downward flux fraction in % computed from the intensity matrix
• check_photometric_consistency — compare matrix-computed LORL and DFF against header declared values
• Handles all ISYM symmetry types including full rotational symmetry (ISYM=1)
• Automatically rejects multi-peak distributions (secondary peak prominence > 5 % of I_max)
• Returns None for undefined cases — never raises unhandled exceptions

Installation

pip install eulumdat-analysis

For development:

git clone https://github.com/123VincentB/eulumdat-analysis.git
cd eulumdat-analysis
pip install -e ".[dev]"

Quick start

from pyldt import LdtReader
from ldt_analysis import half_angle, resample, rotate, luminous_flux, lorl_computed, dff_computed, check_photometric_consistency

ldt = LdtReader.read("luminaire.ldt")

# Half-angle at half maximum per C-plane
result = half_angle(ldt, [0.0, 90.0, 180.0, 270.0])
print(result)
# {0.0: 35.4, 90.0: 36.1, 180.0: 35.8, 270.0: 36.0}

# Resample a raw 2.5°×1° measurement to standard 15°×5°
ldt_raw = LdtReader.read("luminaire_raw.ldt")   # 144 C-planes × 181 γ-angles
ldt_15x5 = resample(ldt_raw)                    # → 24 C-planes × 37 γ-angles

# Flux and photometric consistency check (CIE 190)
flux = luminous_flux(ldt)                        # e.g. 865.3 lm/klm
lorl = lorl_computed(ldt)                        # e.g. 86.53 %
dff  = dff_computed(ldt)                         # e.g. 99.8 %
report = check_photometric_consistency(ldt)
# {"lorl_header": 87.0, "lorl_computed": 86.53, "lorl_delta": -0.47, ...}

Examples

Project structure

eulumdat-analysis/
├── src/
│   └── ldt_analysis/
│       ├── __init__.py
│       ├── half_angle.py
│       ├── resample.py
│       ├── rotate.py
│       └── flux.py
├── examples/
│   ├── 01_basic_usage.md
│   ├── 02_resample.md
│   ├── 03_luminous_flux_range.md
│   └── 04_rotate.md
├── tests/
│   ├── test_half_angle.py
│   ├── test_resample.py
│   ├── test_rotate.py
│   └── test_flux.py
├── CHANGELOG.md
├── LICENSE
└── README.md

Dependencies

• eulumdat-py ≥ 1.0.0 — EULUMDAT parser
• scipy ≥ 1.7 — CubicSpline interpolation and Brent root-finding

half_angle — return values

resample — return values

eulumdat-* ecosystem

New to the ecosystem? eulumdat-quickstart — a step-by-step guide covering all 8 packages with working examples.

License

MIT — see LICENSE.

Context

This package was developed as a practical tool in the context of ISO 17025 accredited photometric testing. It is shared as open-source in the hope that it will be useful to others working with EULUMDAT files in Python.