Cue Tracking

Please note that the title was changed from "Tracking" to "Cue Tracking" in order to make this a more focused topic.

[top]Overview


Tracking, when used and understood, makes a world of sense, particularly for moving lights. In 1975, when Tharon Musser and others were consulting with Century-Strand on the development of the Light Palette, they said they wanted a console that thought like a Lighting Designer thought. On a Piano Board, when you put a Dimmer at say 50% in a cue, the handle stays there until a different cue says to change it, regardless of how many cues there are between. So if in Q1 you bring the blue cyc up to 50% and it says that way until intermission, Q99. Cues2-98 do other things, but never affect the cyc. Then the director tells you he/she wants the cyc red during the first act. So in Q1 you record the "blue cyc" at zero and the "red cyc" at 50%. Make sure that Q99 takes the "red cyc" to 0%. No need to change anything about cues 2-98. Almost all console displays use colors to differentiate between a Channel that has tracked from a previous cue and a channel that moves in the current cue. (I don't know Strand's code). Also, for blackouts and other major cues, it's a good idea to insert a "blocking" cue (Colortran used to call this a "clean-up" cue, Express(ion) calls this an "AllFade). This is a cue that inserts a "hard value" for every channel, and thus stops all tracking. A similar outcome, for one time use, can be achieved using "record Q-only."
The best explanation of tracking, especially for moving lights, I have found is in The Automated Lighting Programmer's Handbook, Brad Schiller. Focal Press, 2004. One more thing: don't get tracking confused with HTP and LTP, they are similar, but different concepts.
There was an excellent article on the topic published in PLSN which you can read here.

[top]Example


For the following example I am using Strand's channel color scheme: Purple are channels moving up, cyan are channels that have tracked, and green are channels going down. This means that channels in cyan do not have commands on them.

Also, lets assume that channel 2 controls a special, channel 3 controls a cyc, and 1 and 4 are area lights (It is totally arbitrary). Lets assume that the cues listed comprise one scene, that ends in a blackout (Q6).

Cue Number	Chan1	Chan2	Chan3	Chan4
Q1	50
	10	FL
Q2	50	FL	10	FL
Q3	50	0	10	FL
Q4	75
	10	65
Q5	0
	10	0
Q6			0

So, say the LD wants the cyc brighter for this scene, he can just tell the channel 3 to be at 20 in cue 1 and it would track through the scene. Like this:

Cue Number	Chan1	Chan2	Chan3	Chan4
Q1	50
	20	FL
Q2	50	FL	20	FL
Q3	50	0	20	FL
Q4	75
	20	65
Q5	0
	20	0
Q6
	0

Then maybe the LD needs channel 1 to be dimmer in cues 2 and 3. Since this is a tracking console the LD need only change the level in cue 2 as it will track into cue 3. It won't effect cue 4 though because channel 1 has a command in cue 4. Like this:

Cue Number	Chan1	Chan2	Chan3	Chan4
Q1	50
	20	FL
Q2	40	FL	20	FL
Q3	40	0	20	FL
Q4	75
	20	65
Q5	0
	20	0
Q6
	0

Now the LD needs the special to come back to full in cue 5:

Cue Number	Chan1	Chan2	Chan3	Chan4
Q1	50
	20	FL
Q2	40	FL	20	FL
Q3	40	0	20	FL
Q4	75
	20	65
Q5	0	FL	20	0
Q6
	FL	0

Uh-oh, looks like that special tracked into our blackout! This is where Block Cues come in handy. The trick is that if you make a cue into a block cue after channels have tracked into it, those channels will still be in it, but no new ones will track in. This is why it is good practice to lay in your black out cues as early as possible and make them block cues. For the next example we are going to assume that Q6 was a block cue before we changed the special (indicated by a "*BL*" for this example).

Cue Number	Chan1	Chan2	Chan3	Chan4
Q1	50
	20	FL
Q2	40	FL	20	FL
Q3	40	0	20	FL
Q4	75
	20	65
Q5	0	FL	20	0
Q6 *BL*	0	0	0	0

The block on cue 6 forces a hard command on each channel. If the director changed his mind and wanted a silhouette instead of a blackout the LD might keep the cyc lit, so it would look like this:

Cue Number	Chan1	Chan2	Chan3	Chan4
Q1	50
	20	FL
Q2	40	FL	20	FL
Q3	40	0	20	FL
Q4	75
	20	65
Q5	0	FL	20	0
Q6 *BL*	0	0	20	0

In this case the channel 3's level appears in white because even though it was riding at 20, it was now told to be there again in Q6. In Strand land this would still show up as Cyan, but for the purposes of the example, it shows there is a hard command on the channel.

Originally Posted by avalentino

...In reading this thread, I thought it might be useful to try to bring a little more clarity to the concept of tracking versus track editing. To start with the easiest concept first.

Almost all desks support track editing functions, regardless of their underlying philosophy as a tracking or preset desk. On a tracking desk, by default, changes to cue data will go forward through the cue list until a move instruction (or block) in encountered. This behavior can be overridden by the [Q-Only/Track] button. If this is appended to a record/update in live, or a level change in blind, you are telling the desk to impact only the specific/selected cue. Most tracking desks have setup option to default the desk to Q-Only mode, wherein the [Q-Only/Track] button now forces a track through the cue list.

On a preset desk, the [Track] button forces the move forward, in a similar manner to a tracking desk. These are behaviors of "track editing," and I believe these ideas were covered earlier in the thread, so forgive me for restating....

The more fundamental difference is how cues get their content in the first place. This is truly what defines a desk as a tracking or preset desk. For the most part, if you happen to be cueing in sequence, you'll not really notice this too much - but you need to know about it.

The following is a pretty simplistic description, but its a place to start.

Let's assume that you have written cues 1 - 10. Those cues contain channels 1 - 10. You then add channel 20 to the stage live. You then do a selective store to create cue 4.5. (whatever the syntax of your desk, something along the lines of channel 20 record cue 4.5).

What will happen on a preset desk is that cue 4.5 will contain only channel 20. Any channels that were active in the previous cue (cue 4) will be driven to zero.

If you did that very same action on a tracking desk, cue 4.5 will contain channel 20 at its current level, and any values in cue 4 will track into cue 4.5.

Depending on the desk you use, you'll see the behavior exhibited in different ways. On a desk with a programmer, if you store a cue, you will get whatever is in the programmer, and any channels not in the programmer, but in use in the previous cue, will track in (unless you override that behavior).

On a tracking desk without a programmer, selectively storing a cue provides similar behavior to working with a programmer. Inserting new whole cues does a lot of cleanup for you automatically, to assure you get the look that you currently want, without moving a lot of non-intensity parameters if it isn't necessary to move them.

For anyone new to a tracking desk, its generally a good idea to work in blind spreadsheet mode for a bit (almost all desks have spreadsheet editing, where you can view a range of channels and a range of cues). Make changes to cues and watch what happens - add new cues and watch what happens. And then play around in live creating new cues between existing cues to make sure you understand how the data is being handled. Delete cues using both tracking and cue only to make sure you understand the impact on subsequent cues.

There are lots of overrides provided in desks to this basic behavior, but this is pretty much the underlying idea. So, in a nutshell, track editing is different from tracking. Tracking desks are very powerful and fast, but require a deeper understanding of the underlying data structures to be used safely. Preset desks have a simpler rule set, but may require more work for certain editing tasks.

For more, see the white paper PDF Entertainment Lighting Control Philosophy.

See also this post, from this thread: http://www.controlbooth.com/forums/l...le-basics.html .