eulumdat

A Rust library for parsing, writing, and validating EULUMDAT (LDT) and IES photometric files.

About EULUMDAT

EULUMDAT (European Lumen Data format) is a photometric data file format used primarily in Europe for specifying luminous intensity distributions from light sources. The format was proposed by Axel Stockmar (Light Consult Inc., Berlin) in 1990 and uses the .ldt file extension.

While the .IES format (IESNA LM-63) is predominantly used in North America, EULUMDAT/LDT is the standard across Europe. Both formats describe the same photometric data but use different conventions.

Format Comparison

Features

• Parse LDT files - Full EULUMDAT format support with European decimal handling
• Write LDT files - Roundtrip-tested output generation
• Export to IES - IESNA LM-63-2002 format export
• Validation - 44 validation constraints with detailed warnings
• Symmetry handling - 5 symmetry types with automatic data expansion
• Photometric calculations - Downward flux, beam angles, utilization factors
• BUG Rating - IESNA TM-15-11 Backlight-Uplight-Glare calculations
• Diagram generation - Platform-independent data for visualizations:
  • Polar diagrams (C0-C180, C90-C270 curves)
  • Butterfly diagrams (3D isometric projection)
  • Cartesian diagrams (intensity vs gamma)
  • Heatmap diagrams (2D intensity grid)
• SVG rendering - Built-in SVG generation with light/dark theming

Installation

Add to your Cargo.toml:

[dependencies]
eulumdat = "0.2"

With serde support:

[dependencies]
eulumdat = { version = "0.2", features = ["serde"] }

Quick Start

use eulumdat::{Eulumdat, IesExporter};

// Parse from file
let ldt = Eulumdat::from_file("luminaire.ldt")?;

// Access photometric data
println!("Luminaire: {}", ldt.luminaire_name);
println!("Symmetry: {:?}", ldt.symmetry);
println!("C-planes: {}", ldt.c_angles.len());
println!("Gamma angles: {}", ldt.g_angles.len());
println!("Max intensity: {} cd/klm",
    ldt.intensities.iter().flatten().cloned().fold(0.0_f64, f64::max));

// Validate the data
for warning in ldt.validate() {
    println!("Warning [{}]: {}", warning.code, warning.message);
}

// Export to IES format
let ies = IesExporter::export(&ldt);
std::fs::write("luminaire.ies", ies)?;

EULUMDAT File Structure

The EULUMDAT format is a plain ASCII text file:

Symmetry Types (Isym)

Diagram Generation

Generate platform-independent diagram data for visualization:

use eulumdat::{Eulumdat, diagram::*};

let ldt = Eulumdat::from_file("luminaire.ldt")?;

// Polar diagram - classic intensity distribution view
let polar = PolarDiagram::from_eulumdat(&ldt);
let svg = polar.to_svg(500.0, 500.0, &SvgTheme::light());

// Butterfly diagram - 3D isometric projection
let butterfly = ButterflyDiagram::from_eulumdat(&ldt, 500.0, 400.0, 60.0);
let svg = butterfly.to_svg(500.0, 400.0, &SvgTheme::dark());

// Cartesian diagram - intensity vs gamma angle (max 8 curves)
let cartesian = CartesianDiagram::from_eulumdat(&ldt, 600.0, 400.0, 8);
let svg = cartesian.to_svg(600.0, 400.0, &SvgTheme::light());

// Heatmap diagram - 2D intensity color map
let heatmap = HeatmapDiagram::from_eulumdat(&ldt, 700.0, 500.0);
let svg = heatmap.to_svg(700.0, 500.0, &SvgTheme::dark());

Theming

use eulumdat::diagram::SvgTheme;

// Predefined themes
let light = SvgTheme::light();
let dark = SvgTheme::dark();

// CSS variables for dynamic theming (web applications)
let css_vars = SvgTheme::css_variables();

BUG Rating (IESNA TM-15-11)

Calculate and visualize the Backlight-Uplight-Glare rating for outdoor luminaires:

use eulumdat::{Eulumdat, BugDiagram, diagram::SvgTheme};

let ldt = Eulumdat::from_file("outdoor_luminaire.ldt")?;

// Calculate BUG rating
let bug = BugDiagram::from_eulumdat(&ldt);
println!("BUG Rating: {}", bug.rating); // e.g., "B2 U0 G3"

// Access zone lumens
println!("Backlight zones: BL={:.0} BM={:.0} BH={:.0} BVH={:.0}",
    bug.zones.bl, bug.zones.bm, bug.zones.bh, bug.zones.bvh);
println!("Uplight zones: UL={:.0} UH={:.0}",
    bug.zones.ul, bug.zones.uh);

// Generate TM-15-11 BUG visualization
let bug_svg = bug.to_svg(400.0, 350.0, &SvgTheme::light());

// Generate TM-15-07 LCS (Luminaire Classification System) diagram
let lcs_svg = bug.to_lcs_svg(510.0, 315.0, &SvgTheme::light());

BUG Rating Scale

The BUG system is used in:

• IDA/IES Model Lighting Ordinance
• LEED v4 Light Pollution Reduction credit
• California Title 24 Energy Code (2022)

FFI Bindings

For Swift, Kotlin, and Python bindings, see eulumdat-ffi.

References

EULUMDAT Format

• Paul Bourke's EULUMDAT Documentation
• AGi32 EULUMDAT File Format
• DIALux EULUMDAT Format Description
• Stockmar, A. W. (1990): "EULUMDAT - ein Leuchtendatenformat für den europäischen Beleuchtungsplaner", Tagungsband Licht '90, pp. 641-644.
• Stockmar, A. W. (1998): "EULUMDAT/2 - Extended Version of a Well Established Luminaire Data Format", CIBSE National Lighting Conference 1998, pp. 353-362.

IES Format

• AGi32 IESNA LM-63 Format
• ANSI/IESNA LM-63-2002: Standard File Format for Electronic Transfer of Photometric Data

BUG Rating

• IES TM-15-11 BUG Ratings Addendum (PDF)
• NaturaLED BUG Ratings Explained

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.