2 Model philosophy
In order to be able to reason about the nature of the fixture DMX related information contained in AtlaBase, we have defined three models that could be used to describe the DMX behaviour of a fixture; the component, command and display models.
We used to provide data in both the component and command model, but due to lack of demand we now only provide data in the command model.
The following three illustrations explain the differences between them using the Clay Paky Stage Zoom 1200’s combined shutter/dimmer channel as an example:
The component model
- The fixture is equipped with a shutter. You can can set it in open position by applying any DMX value between [0, 139] or [244, 255] on channel 4 or make it strobe from slow to fast by moving from DMX value 140 to 243 on channel 4.
- The fixture is equipped with a white light source. You can dim it by moving from DMX value 0 to 127 on channel 4. You can also have it on full level by applying DMX values [128, 255] on channel 4.
The command model
- On channel 4, DMX 0-127 the white light output scales from zero to full.
- On channel 4, DMX 128-255 the white light output is at full.
- On channel 4, DMX 0-139 the shutter is open.
- On channel 4, DMX 140-243 the shutter will flash from slow to fast.
- On channel 4, DMX 244-255 the shutter is open.
The display model
- Channel 4, DMX 0-127, use label “Dim 0 -> F”
- Channel 4, DMX 128-139, use label “Dim F”
- Channel 4, DMX 140-243, use label “Strobe S -> F”
- Channel 4, DMX 244-255, use label “Dim F”.
Display model data is non-semantic, it is descriptive text in various languages and lengths, non-interchangeable between manufacturers and consoles, and possibly even with variations within the same console in order to fit displays of different size.
It is possible to convert back and forth between Component and Command model data. They contain the same information, only structured differently.
It is possible to convert Component or Command model data to Display model data given a set of language and conversion rules.
It is almost never possible to convert Display model data to either of the other models because of it’s lack of information (which is the result of trying to create descriptive and compact labels).
Because of the previous point, it is not possible to use Display model data in any accurate fixture replace situation.
All fixture manuals and many lighting consoles contain Display model data.
All visualizers and some lighting consoles require Component or Command model data.