eulumdat-quickstart

A step-by-step guide to the eulumdat-* Python ecosystem

The EULUMDAT format (.ldt) is the standard file format for luminaire photometric data, widely used in lighting design, photometric testing laboratories, and luminaire manufacturing. Each file contains a text header (luminaire metadata, lamp data, photometric factors) and an intensity matrix in cd/klm across C-planes and γ-angles.

The eulumdat-* ecosystem is a set of 8 Python packages that let you read, analyse, and visualise .ldt files — from simple header inspection to full photometric datasheet generation. It was developed in an ISO 17025 accredited photometry laboratory. All packages are available on PyPI.

This guide walks through each package step by step, using two real sample files. No prior photometry knowledge is required, but basic Python familiarity is assumed.

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⚠️ Import names differ from package names. The PyPI package name (used with pip install) is not the same as the Python import name. Always refer to the table below.

PyPI package	Python import	Version
eulumdat-py	from pyldt import ...	1.0.0
eulumdat-symmetry	from ldt_symmetry import ...	1.0.0
eulumdat-plot	from eulumdat_plot import ...	1.0.3
eulumdat-luminance	from eulumdat_luminance import ...	1.3.1
eulumdat-ugr	from eulumdat_ugr import ...	1.0.2
eulumdat-analysis	from ldt_analysis import ...	1.0.0
eulumdat-report	from eulumdat_report import ...	1.1.0
eulumdat-ies	from eulumdat_ies import ...	1.1.0

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Dependency chain

eulumdat-py  (pyldt)                           ← core, zero dependency
    ├── eulumdat-symmetry  (ldt_symmetry)       ← symmetrisation, ISYM detection
    ├── eulumdat-plot      (eulumdat_plot)       ← SVG polar intensity diagram
    ├── eulumdat-analysis  (ldt_analysis)        ← half-angles, FWHM
    ├── eulumdat-luminance (eulumdat_luminance)  ← luminance tables, polar diagram
    │       └── eulumdat-ugr (eulumdat_ugr)      ← UGR catalogue (CIE 117/190)
    ├── eulumdat-report    (eulumdat_report)     ← HTML/PDF datasheet (CLI + API)
    │       (depends on plot + luminance + ugr + analysis)
    └── eulumdat-ies       (eulumdat_ies)        ← bidirectional LDT ↔ IES LM-63-2002

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Sample files

Both files in samples/ represent the same luminaire:

File	ISYM	C-planes	γ-angles	Lines	Description
sample_isym0.ldt	0	24	37	991	Raw measurement — all C-planes stored
sample_isym4.ldt	4	7	37	362	Symmetrised — quarter symmetry

Luminaire characteristics:

• Type: LED linear luminaire
• Housing: 1480 × 65 × 10 mm
• Luminous area: 1480 × 63 mm
• Lamp: LED module, 12 334 lm, 66.8 W
• LORL: 100 % / DFF: 100 %

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Sample report

The final output of this guide is a complete A4 photometric datasheet. Click the image to open the interactive HTML report:

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Table of contents

Step	Guide	Topic
0	docs/00_setup.md	Setting up your environment
1	docs/01_parse.md	Parsing an LDT file
2	docs/02_symmetry.md	Detecting and applying photometric symmetry
3	docs/03_plot.md	Polar intensity diagram
4	docs/04_luminance.md	Luminance table and polar diagram
5	docs/05_ugr.md	UGR catalogue
6	docs/06_analysis.md	Beam half-angle (HAHM)
7	docs/07_report.md	Full photometric report
—	docs/08_ies.md	Bonus — Working with IES files