eulumdat-luminance

Luminance table generation from EULUMDAT (.ldt) photometric files — extension to eulumdat-py.

Features

• Luminance table (cd/m²) computed from intensity distribution and luminous area geometry
• UGR grid (C: 0°–345° in 15° steps, γ: 65°–85° in 5° steps) with automatic bilinear interpolation when the native LDT resolution does not match
• Full native grid mode for detailed photometric analysis
• result.at(c_deg, g_deg) — bilinear interpolation at arbitrary (C, γ) angles
• result.projected_area(c_deg, g_deg) — projected luminous area (m²) at arbitrary angles, required by eulumdat-ugr for solid-angle computation
• Polar luminance diagram (SVG + PNG/JPG): all 24 C-planes visible simultaneously, one curve per γ angle, blue gradient palette, optional threshold circle
• Print-ready output by default (PolarStyle.for_print(width_cm=10, dpi=150, font_scale=2.11) — 10 cm at 150 dpi, Arial 9pt equivalent); customisable via PolarStyle.for_print(width_cm, dpi)
• CSV and JSON export

Installation

pip install eulumdat-luminance

Dependencies

• eulumdat-py — EULUMDAT parser
• numpy, scipy
• vl-convert-python — SVG rasterisation
• Pillow — JPG conversion

Quick start

from pyldt import LdtReader
from eulumdat_luminance import LuminanceCalculator, LuminancePlot, PolarStyle

ldt    = LdtReader.read("luminaire.ldt")
result = LuminanceCalculator.compute(ldt)

print(f"{result.luminaire_name} — {result.maximum:.0f} cd/m²")

# Interpolate luminance at arbitrary (C, γ)
lum  = result.at(c_deg=12.0, g_deg=67.0)           # float, cd/m²

# Projected luminous area at arbitrary (C, γ) — used by eulumdat-ugr
area = result.projected_area(c_deg=0.0, g_deg=65.0) # float, m²

plot = LuminancePlot(result)
plot.polar("polar.svg")   # default: 10 cm at 150 dpi, Arial 9pt equivalent
plot.polar("polar.png")

# Custom size: 8 cm at 300 dpi
plot.polar("polar_report.png", style=PolarStyle.for_print(width_cm=8, dpi=300))

# Get SVG as a string for inline HTML embedding (no file written)
svg_str = plot.polar_svg()

Example output

Sample 04 — linear luminaire 1480 × 63 mm, 12 334 lm — default style (PolarStyle.for_print(width_cm=10, dpi=150, font_scale=2.11))

Running the tests

# All tests (numerical validation + diagram generation)
pytest

# Numerical tests only (fast)
pytest tests/test_calculator.py

# Diagram generation only
pytest tests/test_polar_diagram.py

# Verbose with print output
pytest -v -s

# Filter by sample
pytest -k sample_04

# Filter by test type
pytest -k "svg"                  # SVG generation only
pytest -k "png"                  # PNG generation only
pytest -k "for_print"            # print sizing test (8 cm / 300 dpi)
pytest -k "word"                 # Word/PDF report test (10 cm / 150 dpi)
pytest -k "Relux"                # Relux numerical validation (30 tests)
pytest -k "not Smoke"            # exclude smoke tests

# Coverage
pytest --cov=eulumdat_luminance tests/test_calculator.py

License

MIT