Simple (?) Undead Turning questions...

[stringbean]

Do you need a LoS to Turn Undead, and/or do they need a LoS to you?

Can you Turn an invisible undead creature if you know he's "around here somewhere" but do not know specifically where?

 

[LokiDR]

Some relevant information from the SRD.

Turning Checks
Turning undead is a supernatural ability that a cleric can perform as a standard action. It does not provoke attacks of opportunity. A combatant must present a combatant's holy symbol to turn undead. Turning is considered an attack.
...
Range
A combatant turns the closest turnable undead first, and the combatant can't turn undead that are more than 60 feet away or that have total cover relative to a combatant.

They must see you. You must point at them. It also reads like a 60' cone, so I would say no random turning: pick an arc. But that is open to interpretation.

 

[Voadam]

I don't get a cone from that srd quote.

If you were surrounded by undead and held up your holy symbol, the closest to you would be affected whether they were behind you or in front of you.

Cover can block it but this does not imply that a vamp who closes his eyes is immune to turning.

I treat the presenting the holy symbol as the somatic component of the act.

I would allow PCs to blast out a 60' radius positive energy burst to clear invisible undead.