I'm sure I've read the answer to this somewhere but I can't find the reference...
My understanding is that a device can be enchanted with effects that use its wielder's senses. So, a wand of fireballs (creo ignem, R: Sight, D: Mom, T: Ind) uses the the wielder's sense of sight to find the target.
But what if I wanted the device to use its own senses? So instead of a wand of fireballs I wanted Flambeau's Greek Fire Emplacement (creo ignem, R: Sight, D: Mom, T: Ind). In this case, the emplacement must be autonomous and find its own target.
I'm assuming that the device needs some form of "sight", but I'm not sure what that effect looks like. Leaving aside any question of recognising valid targets from hapless covenfolk, how does the Emplacement gain the sense of sight?
Is it a R:Personal, D:Sun, T:Vision effect (boosted to a constant effect)? That looks enough to give the Emplacement the ability to "see", which I could then use as a trigger on the CrIg effect.
Use a separate Intellego effect as in the lab chapter under making magic items. This way the other effect can sense the target on its own. I don't have my books at work but I think I remember one of the magi in one of the Tribunal books having such.
Thanks Rich. I should have put that the effect I suggest was itself an Intellego Imaginem effect with R:Personal, D:Sun, T:Vision. This would then be the trigger (whether for the "shoot anything that moves" effect or the "work out if you want to shoot it" effect).
I think I'm happy with this approach.
One side effect seems to be that the device can "sense" all around itself in this case as there are no "eyes" to give a narrow field of vision.
I have no problem with items sensing 360 degrees even if they had "eyes". I note that an InIm effect will sense species, so "anything that moves that emits species" is more likely the effect. I suggest that if you want it to blast people use InCo (invisible people or not), Animals InAn, etc.