[Brian Jones]

with a plane you can use the Side property you will find in the Texture tag. Put two textures on the plane set one to Front, the other to Back

[Brian Jones]

you can clear the Link in the Guides tab (or delete the original object) and then move the hair but not with the Move tool, I think it can only be done with the Hair tools. In the Hair menu set Mode to Roots then you can use Hair/Tools/Move to move the hair. The problem is the only thing that will render (without tweaking) is the guides since the hairs are usually interpolated between the guides but need a surface to determine the start point (a poly usually). You can still have hairs bit you have to do it in the Cloning tab of the Hair object, set Clone to something non-zero then spread them out at root and tip with the Root and Tip settings. Still acts as hair.
If you only need static hair the other way to do it is to Generate poly or spline hair and make that editable then that object will be moveable with normal methods

[Brian Jones]

…also a problem since the emitted ‘sparks’ remain for their lifespan once the original particle disappears maybe movement to the new particles or age effects would make that be ok

544_volcanotest.zip

[Brian Jones]

and you can’t swap groups or kill the particle, it just leaves the trail behind and it doesn’t disappear.
I’ve seen a couple of tutorials for fireworks, basically you emit particles then each particle is used to generate it’s own trail of particles that seems like it might work. I’ll look. You might want to google.
The way to upload are the icons above the message pane as you post here. The one that looks like a micro-floppy (far right icon) is for file upload. Hover over them for tool tips.

[Brian Jones]

it looks your way in 10.5 too but the 11.5 demo it looks like the tutorial, upgrade looks like it.

[Brian Jones]

I see, the trace stays, getting shorter, until it catches up with the particle termination point. hmm….

[Brian Jones]

The rapidshare page won’t let me dl so here’s a test I did.

539_tracetest.zip

[Brian Jones]

are you trying to move the hair from the object that it was created on?

[Brian Jones]

In the Tracer set Limit to From End and the Amount to something less than your particles life (in your case maybe start with 25 and go from there)

[Brian Jones]

It looks like the whole thing is planned out beforehand, they went to the scene, took some pictures from where the projectors are going to be, render the video to match the pictures and play it as a file from (a) laptop(s) connected to the projectors. There is nothing spontaneous about it (note the McAffee ad near the end – sponsors probably) so why not render and get the best quality images first?