EULUMDAT Files

EULUMDAT files use the .ldt extension. The format is widely used in European lighting workflows for exchanging luminaire photometric data.

What the format contains

An LDT file stores luminaire, lamp, geometry, symmetry, angle table, and luminous intensity information in a line-oriented text structure. It is often used for product photometry and lighting calculation programs.

Use in IntensityView

IntensityView can open and save .ldt files. On import, the application reads the C-plane and gamma angle data and converts the intensity table into an internal intensity mesh. On export, IntensityView writes EULUMDAT-compatible text data from the selected document or intensity distribution.

Best practice

Use EULUMDAT when a European lighting calculation workflow or customer deliverable requires .ldt. Keep an .ewi master file when preserving richer internal properties, multiple channels, or colorimetric editing data matters.