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Uniform data format for the lighting industry: Global Lighting Data Format

DIALux

GLDF - Global Lighting Data Format


DIAL and RELUX are working together to develop a new data format for lights and sensors, the Global Lighting Data Format (GLDF). This format will be used, among other applications, in the lighting design programs of both DIALux and RELUX.


GLDF is an open, free format that can be used across the entire lighting industry and meets the latest BIM process requirements. Manufacturers, planners and even software manufacturers will benefit from this new format.


Impetus and initial situation
Until now, manufacturers have had to deal with the fact that users require internal product information in different formats and for different purposes. Planners and designers use several different programs for different purposes and expect product data to be available, and of course uniform, across all applications. Software manufacturers require comprehensive and the most up to date product information. This data must include all information required for the respective purpose.
The Global Lighting Data Format (GLDF) provides the following advantages for everyone involved: Manufacturers only need to maintain and offer a single format. All processes operated by manufacturer data can access the information from the GLDF. Planners can find all information on a product in the GLDF. The file can be used by all programs and applications. The information is always identical, ruling out differences between different file versions. Software manufacturers can find great information for their (design) programs. Manufacturers are incentivised to maintain the information and keep it up to date as they no longer need to create new formats for many different purposes. 

Current status of electronic lighting documentation
Various descriptions for lights are currently available for different purposes.
Standard photometry formats such as Eulumdat, LM63, TM-14 or UNI 11733-2019 are available for creating technical data sheets or calculating a lighting system. These formats document physical properties of lights and lamps. Measured properties are presented and can be interpreted using formulas and standardised application rules.
These formats contain very little further information that would be required for a complete BIM-process, including system design, commercial processing or facility management.
For information required by retailers, for example, there is the ETIM format which is common in Germany and also used in other countries. This is designed for data exchange between the manufacturer and retailer, and compiles product descriptions. This format cannot be used for light planning.
Modern data formats that are used in CAD and lighting design programs include ULD (DIALux) ROLF (RELUX), RFA (Revit) or even IFC (OPEN BIM). These formats combine different requirements. In lighting design programs, light is calculated and the most complete product information possible is given for selection and ordering. In contrast, the RFA and IFC data formats try to map the product in the CAD and BIM process without sufficiently considering the lighting technology.

Current status of the new Global Lighting Data Format (GLDF)
The new Global Lighting Data Format (GLDF) has been developed to fully map lights and presence or movement sensors for all purposes. Preliminary work from various committees, such as the ZVEI BIM workgroup, has been incorporated. Part of the GLDF is, of course, photometric and spectral information as well as geometrical, electrotechnical, commercial and maintenance information. The features are described in CEN TS 17623, "BIM Properties for lighting - Luminaires and sensing devices". Further parameters can also be saved. In terms of BIM, a GLDF can be used in a project from the first design phase to recycling.
DIAL and RELUX have designed a data structure that can map all aforementioned parameters and therefore makes data exchange between applications and stakeholders possible. In order to reach the largest possible number of users, the format and related documentation are provided free of charge.
The format will continue to be curated by the participating companies and further developed according to requirements.
The documentation should be released over the course of 2021. A beta phase of the format is to start in the first half of 2021. Software manufacturers (light planning, CAD, PIM) and lighting manufacturers must then implement and offer this format in their systems.  

Set-up & structure
The GLDF is set up in an XML structure (Extensible Markup Language). This is ideal for displaying hierarchically structured data. Other advantages are readability for people and machines, platform independence and very wide distribution. 
The GLDF is a container format within which the data supplier can integrate all content. These include texts, images, light distribution curves (LVK), spectra, 3D models, etc. A product can also contain different supplementary information. For example, a light can be described as a cuboid with length, width and height, but a detailed 3D model can also be provided. The reading application can then decide whether to display a simple or a complex model. Products can be simple or complex depending on real life requirements. This means it is also possible to map a simple recessed luminaire as well as a complex lighting system with many light exits, which is individually dimmable and also color-changing for "Human Centric Lighting". Furthermore, systems can also be equipped with motion sensors and emergency lighting units.
The structure is defined in such a way that individual elements as well as the entire content can be signed. This makes it possible to see whether the content has been changed. This gives the manufacturer or the supplier of the data and planners great internal security when using GLDF files. If parts have been changed, e.g. power input, LVK or manufacturer designation, this can be identified immediately when checking the signature.
As well as the documentation, an XML Scheme Definition (XSD) is also provided. Software developers can therefore easily implement the GLDF interface into a PIM system (Product Information Management). Both the structure and data types are defined within the XSD.
It is still up to the manufacturer of the specific software to decide which data the software program takes from the available framework. Thus, a program is able to link the scope of the read-in information to the licensing by the user or via the licensing of the data provider (manufacturer). A combination is also possible.

The GLDF format can present the geometry of a product in three ways:

  • As a simple geometry, cuboid or cylinder with the length, height and width or diameter dimensions (as part of the generic model)
  • As a generic 3D model where an archetype is described and the associated dimensions are defined (e.g. floor lamp with dimensions for base, pole and lamp head)
  • As a realistic 3D model with the geometric, photometric and mechanical information in an OBJ format. Textures, any angle of rotation and several light exits can be defined here. 
     

Further information
Further information on the Global Lighting Data Format will be available shortly on the DIAL and RELUX webpages. The www.gldf.io website provides the description of the format as well as tools, sample files and the option to record suggestions and comments. The two companies DIAL and RELUX jointly maintain this website.