Two years ago a professional gang broke into the Bureau de Change next door during the night. One of the cameras was a small IP camera which I had advised them to install as I thought an off-site recording would be a good thing. However, they were so professional that they recognized the IP camera and covered their faces before they disabled it; we have seen the entire footage.

They did not touch the main security cameras, but dipped the DVR to which all six cameras were connected into a bucket of water. The police have not managed to recover anything from the HDD.

The whole thing makes me wonder whether it is wiser to try to scare intruders away by means of visible CCTV or using hidden cameras to catch them, as visible cameras only made the job easier for the thieves.


  From security point of view is it better to have camera hidden or visible


Yes.

Hidden and visible cameras emphasize different security values.

Visible cameras provide deterrent value as much or more than recording value:  


They may cause less prepared or less dedicated criminals to think twice.
They may encourage actions or routes which benefit the defender (e.g., walking around the visible camera field may force the attacker into the field of another, hidden, camera).


Visible cameras are more susceptible to avoidance or disabling, though, because they are obvious.

Hidden cameras provide improved recording value, in that they can be more survivable than visible cameras.  However, they may have more limited fields of view, and they don't provide any deterrence.

The security decision to go with hidden, visible, or both, should be dictated by the site and the threat.  

A convenience store is going to want to emphasize visible cameras, as deterrence is more valuable in that threat environment.  A museum might emphasize hidden cameras, partially because deterrence is less of an issue and partially because obvious cameras detract from the atmosphere they want to provide for their customers.

In all cases, the Digital Video Recorder (DVR) needs to be better protected than it was in this case.  It should be protected well enough that legitimate employees can't tamper with it - certainly the attackers in the case you describe probably knew video stayed local to the site, knew it could be disrupted, and possibly even had "inside information" that allowed them to go straight to it.
