Import a GDTF profile
Import a manufacturer's GDTF fixture profile, including measured color data that sharpens how Spectralite renders color on that fixture.
GDTF, the General Device Type Format, is an open, cross-vendor file format that describes a lighting fixture: its DMX modes, its channels and their functions, its physical geometry, and, when the manufacturer measured them, the real colors of its emitters. One .gdtf file holds everything Spectralite needs to build a fixture definition, so importing one is usually faster and more accurate than authoring a definition by hand. For what a definition is and how it is structured, see Fixtures and patching.
What Spectralite reads from a GDTF file
An import pulls two independent kinds of data out of the file.
The first is the fixture's structure: its modes, the channel each function lives on, and the geometry that places its emitters in space. This is what lets you patch the fixture and drive its dimmer, movement, and color channels at the right addresses.
The second is measured color data, present in files where the manufacturer characterized the fixture. For each emitter a GDTF file can carry its exact color coordinate, its relative brightness, and a response curve describing how the emitter's output tracks its control level. Spectralite feeds this into the color engine, which builds each fixture's reachable color range and works out how to reproduce an authored color on that fixture's real emitters. When measured data is present, the engine renders color against the numbers the manufacturer published rather than generic assumptions, which raises how closely the fixture matches the color you authored. The colorimetry itself is covered in Color; this page stops at where the data comes from.
Import a GDTF file
Choose Project > Library Manager and open the Fixtures tab. Click Import GDTF.
Choose the file and where it goes
In the Import GDTF dialog, decide whether to tick Save to library for all projects. Leave it off to bring the fixture into the current project only; tick it to keep the fixture in your local library so every project can reach it. Then click Select File & Import and pick the .gdtf file. Spectralite parses it, builds the definition, and adds it to the fixture catalog.
Re-importing the same fixture does not create a duplicate. Each GDTF fixture carries a stable identifier, and Spectralite matches on it, so a second import of the same profile updates the existing entry instead of adding a second one.
Add it to your show
Importing puts the fixture in the browse catalog, not yet in your project. Add it and give it an address the same way as any library fixture.
Add a fixture
Bring the imported definition into your project.
Patch a fixture
Set its universe, address, and mode.
Under the hood: measured color data
This section is for readers who want to know how much the color data affects the result. You can import and use a fixture without any of it.
When a GDTF file measures its emitters, Spectralite uses those measured color coordinates in place of the nominal, generic ones it would otherwise assume. A profile without measured data still works: the engine falls back to sensible defaults drawn from a large survey of real fixtures, so an uncharacterized fixture renders reasonably. The difference is accuracy, not whether color works at all.
Spectralite is honest about the quality of what it imported. For each emitter it records the provenance of the color coordinate: whether the file named that emitter directly, whether it was matched by its color, or whether no usable value was found and a default was substituted. It also sorts each profile into a data-quality tier, from a profile with real measured colors down to one that declares color mixing but carries no emitter data. Because real GDTF files in circulation sometimes hold placeholder or physically impossible color values, every emitter color is validated against the range of visible light before it reaches the color solve.
Be clear about the boundary. Spectralite consumes the manufacturer's measured profile. It does not offer a per-unit tool where you measure your specific fixture and enter your own corrections; "measured" here means the values the file declares, tracked with their provenance and quality, not a calibration you perform on each physical light.
Related
- Fixtures and patching: the fixture model an import builds.
- Color: how measured emitter data feeds the color solve.
- Create a fixture definition: author a definition by hand when no GDTF file exists.
- Add a fixture: bring an imported fixture into a project.
- Share a patch: move a rig between projects and machines.