Lighting software data format
Dial and Relux say the new Global Lighting Data Format (GLDF) is an open and free protocol that, crucially, will work with the latest Building Information Modelling (BIM) standards and processes.
Until now, manufacturers have had to deal with the fact that users require internal product information in different formats and for different purposes. Engineers and designers use several different programs for different purposes and expect product data to be available, and of course uniform, across all applications.
With the GLDF, manufacturers only need to maintain and offer a single format. All processes operated by manufacturer data can access the information from the GLDF. The information is always identical, ruling out differences between different file versions. 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. Currently, various configurations for lights are used 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 retailers, for example, there is the ETIM format which is common in Germany and some other countries. This is designed for data exchange between the manufacturer and retailer, and compiles product descriptions.
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, lighting 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.
The 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 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 the parameters making data exchange between applications and stakeholders possible. The format will continue to be curated by the participating companies and further developed according to requirements. The companies say documentation should be released over the course of 2021 with a beta phase of the format due 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.
The GLDF is set up in an XML structure (Extensible Markup Language) as it is suitable 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 colour-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 – such as the 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 de- fined 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 dimen- sions 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.