Import a GDTF profile
Import a manufacturer's GDTF fixture profile, including the measured color data Spectralite uses to match authored colors on that fixture.
GDTF, the General Device Type Format, is an open, cross-vendor file format that describes a lighting fixture. A GDTF file describes the fixture's DMX modes, its channels and their functions, and its physical geometry. When the manufacturer measured them, the file also holds the real colors of the fixture's emitters. One .gdtf file holds everything that Spectralite needs to build a fixture definition. An import is usually faster and more accurate than a definition authored by hand. Fixtures and patching explains what a definition is and how it is structured.
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. With this data, you can patch the fixture and drive its dimmer, movement, and color channels at the right addresses.
The second is measured color data. A file has it when the manufacturer characterized the fixture. For each emitter, a GDTF file can carry:
- its exact color coordinate
- its relative brightness
- a response curve that describes how the emitter's output tracks its control level
The color engine uses this data to build the reachable color range of each fixture. It also uses the data to work out how to reproduce an authored color on the fixture's real emitters. With measured data, the engine renders color against the manufacturer's published numbers, so the fixture matches the color you authored more closely. Color covers the colorimetry.
Import a GDTF file
- Choose Project > Library Manager.
- Open the Fixtures tab.
- Click Import GDTF.
Choose the file and where it goes
In the Import GDTF dialog, decide where the fixture goes:
- To bring the fixture into the current project only, leave Save to library for all projects off.
- To keep the fixture in your local library so every project can use it, tick Save to library for all projects.
Then click Select File & Import and pick the .gdtf file. Spectralite parses the file, builds the definition, and adds it to the fixture catalog.
Every import adds a new fixture. If you import a profile that is already in your library, or built in, that fixture and the projects that use it stay as they are.
Check what the import changed
Not everything a GDTF file can describe fits a Spectralite fixture definition. If an import gives something up, the dialog lists it, grouped by mode, before it closes. Dropped means the fixture lost something that the file declares, such as a channel, a function or a whole mode. The fixture can then misbehave on the rig. Adapted means the function is kept in another form, such as several emitters drawn as one pixel. Before you patch a mode with dropped notes, compare it with the fixture's manual.
Add it to your show
Spectralite places the imported fixture at universe 1, address 1. Give it its address in the Fixtures panel. A fixture saved to the library also appears in the browse catalog, so you can add it to other projects like 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
The details below cover how much the color data affects the result. You do not need them to import and use a fixture.
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 defaults taken from the measurements in manufacturers' own GDTF files, so an uncharacterized fixture still renders reasonably. Measured data makes the color more accurate.
Spectralite tracks the quality of the color data that it imports. For each emitter, it records the source of the color coordinate:
- The file named that emitter directly.
- Spectralite matched the emitter by its color.
- The file had no usable value, and Spectralite substituted a default.
Spectralite also sorts each profile into a data-quality tier. The tiers go from a profile with real measured colors down to one that declares color mixing but carries no emitter data.
Real GDTF files sometimes hold placeholder or physically impossible color values. So before the color solve uses an emitter color, Spectralite checks it against the range of visible light. If the file's own numbers are doubtful, or the file carries no measured color at all, the Address Space panel flags the fixture after you patch it. The flag has a sentence that says what to do.
Spectralite uses the manufacturer's measured profile as the file declares it. "Measured" here means the values in the file, with their provenance and quality tracked. The app has no tools for measuring your own lights or entering corrections.
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: print a patch sheet as a PDF or publish it as a public link.