Unified luminaire data file
File type: Various data file
A .uld file is a Unified luminaire data file used by DIALux lighting-design software.
It contains the data needed to represent a luminaire, including its light distribution and other product information.
File type category:
Various data file
Date updated: October 16, 2026
The Unified luminaire data format is associated with DIALux, a Windows application for planning and calculating lighting installations. It was used by DIALux 2 and later versions.
A .uld file can contain information about a luminaire's light distribution, available equipment, photographs, descriptive text and 3D geometry. This allows the luminaire to be loaded into a DIALux project for lighting calculations and visualisation.
Only DIALux project partners are able and allowed to create this format. ULD files are therefore normally distributed as manufacturer or project-partner luminaire data rather than authored manually by the end user.
Open the .uld file in DIALux on Microsoft Windows. In DIALux, import or load the file as luminaire data so that the luminaire becomes available for use in a lighting project.
There is no general-purpose conversion that preserves all of the information in a ULD file. The file is intended to be loaded directly into DIALux. It is unlikely that this type of .uld file can be converted to anything else.
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