Gel scrollers are a fixture that can be attached to the front of a Parcan to allow the colour of the gel to be changed remotely from a lighting desk, instead of requiring somebody to physically remove one gel & replace it with another.
A scroller consists of a long roll of gel in different colours, one after another, with a spool on either side of a round opening through which the light shines - akin to a roll of transparency on an overhead projector. When activated by a DMX command, the spools rotate by motor, scrolling different coloured gels in front of the Parcan.
The union owns 12 ChromaQ Colour Changers, which are attached to parcans on the side bars in Venue 1, 6 on each side. They require 4-pin DMX, as along with standard DMX data they require power for the motors and fans. Because of this, there is a ChromaQ power supply/DMX mux mounted to the Space frame in the centre of the venue, above the Octagon, which feeds these fixtures.
The scrollers are usually programmed to either 1 or 2 faders on the Pearl & the position of these fader between 0% & 100% dictates which colour the scrollers will advance to. Flinging the fader all the way to 100% will give a nice chase of colours for a while, as scrolling from one end of the roll to the other takes several seconds. MagicQ is also programmed with a set of slow colour chases for the scrollers, as well as individual control.
Whether these can truly be considered "intelligent" fixtures or not is open to debate.