How to see through walls...or at least as long as your GPS is accurate.

1. Get X3 (Minimum) GTC Spy Drones
2. Give them good cameras
3. Install Rangefinders
4. Get Cybereyes and a Commlink
5. Get some really good armor piercing ammunitions - or at least a powerful gun and no flechette ammo.
6. Install Wallspace in everything and add a custom texture pack of your choice.

Accurate Wallhack Targeting
The drones all lock on to a specific target and through triangulation they will give the character accurate GPS location of the target. Wallspace software will give a nice AR X-ray look of things in the way like walls, allowign the character to take pot shots straight through walls to hit their target.

This should in all fairness give the following bonus:
AR: +3 (+1 for each drone locked up to +3 total)
Blind Fire: -6 (you do NOT see your target, only a representation of them through AR)
Surprise: Target may not dodge (You shot him/her througha wall...)

Or just use Radar Sensor / Ultra-wide-Band Radar

Yes, as long as your target is within a hundred meters.

This is also useful for shooting targets in another building wiht an anti-material rifle.

Tacnet?

Take the spydrone, stuff an UWB-Radar in it. Done.

The drawback is that those things can be so easily jammed.

Don't a number of 6th world walls make use of augmented reality overlays, and photovoltaic paint? Not every wall would have the greatest set of sensors-but hacking them might get some similar results.

You would still need the drones, photovoltic paint will not allow you to make them invisible...but...

Yes, you could have the drones create a mirror of what they see on the opposite wall that the character is facing in full 3D giving the character a simulated view of teh room.

Don't forget that Blind Fire uses Intuition instead of Agility.

Which is why many technomancers/deckers are a lot scarier to the gun bunny. they can shoot you through the wall more often then the cybermonkey

Not likely, as there are very few ways to augment your Intuition. Any Gunbunny running around with a 2 Intuition is not a Gun Bunny, as Far as I am concerned. The scores will likely be similar between the Hacker/Technimancer/Street Sam/Adept Gunbunny (at least they are at our table, intentional outliers being the exception). And likely not more than a point in difference.

I'd also like to point out that Blind Fire's int-swap really doesn't matter if you're shooting from a Drone.
Jumped in riggers use Sensor instead of response, which they were probably using anyway due to active or passive sensor targeting.
Autonomous drones use pilot for all mental attributes, and command replaces the attribute portion of a test.

Also, I don't think blind fire actually applies to someone who has been targeted by UWB. You do not have to guess or estimate their position at all; you know precisely where they are. You can see them perfectly fine until someone turns on a jammer.
The defender still gets the benefit of good cover, though.

I would also like to point out that Indirect Fire(arsenal 162) specifically provides a way around Hidden Target/Blind Fire penalties.
Note: Due to 4th Edition/Anniversary Edition rules fuckery, the Target Hidden penalty has been renamed to Blind Fire in anniversary edition.
4th: page 150: Target Hidden (Blind Fire) as opposed to 4a page 150: Blind Fire. They are identical rules other than the name change/clarification/obfuscation.

Ars 162: Under most circumstances, a character trying to use a ranged weapon against a target she cannot see or sense must apply a –6 Target Hidden dice pool modifier to such attacks. In certain situations, however, a character, drone or vehicle may acquire a target lock for a weapon that is in a different location. This enables the weapon to engage in indirect fire on a target even when it does not have line of sight or a sensor lock on the target
163: The spotter’s net hits are added to the attacker’s dice pool. The only modifiers that apply are a –4 modifier for informationguided indirect fire or a –2 modifier for target-designated indirect fire.

So yeah. Wallhacking through spotters and sensor networks are already covered in the rules.

The defender should not get a defense roll - he is (normally) unaware of an attack coming through a wall.

Nah, he'll just get a dicepool bonus to soaking equal to cover.

Actually, he gets a bonus equal to the Barrier rating of the material being shot through. It effectively acts as Armor...

Actually, it is the Armor Rating of the Barrier (i know, i'm nit-picky ^^)

I was actually discussing hacking the walls sensors to use them to monitor the room. Obviously they'd be of limited use-but it's an option.

Indeed.... The Armor Rating, of the Barrier Rating, which has Armor and Structure. Obviously, I only meant the Armor part of the equation (Since it is used as Armor), not the Structural Rating of the Barrier.

Did I out-pick your Nit?

But it was such a great Nit too!

Heh...

Any two imaging devices inside a room will typically make it possible to exactly calculate the position of any target within the vision of both sensors [unless for some reason it's impossible to calculate the position of the sensors relative to the shooter, and typically lots of trigonometry will get you that], using off-the-shelf image processing software. The proliferation of sensing devices in Shadowrun would likely be extraordinary; already, every Wiimote in the world is a camera, every Kinect in the world is a camera; most phones have cameras, and most laptops and tablets as well; many desktop computers and televisions have cameras. In Shadowrun, many more devices would have some kind of imaging device, if only to see someone's in front of them, and to know who that person is. Certainly most walls [so they can also be tridphones] in middle-class [and above] areas would be video walls of one kind or another. Motion lights. The soy dispenser has a camera so it can track who ate what, for your diet software; scales have an imaging sensor for the same reason.

This is presuming, of course, that they don't just have a robot vacuum. Any robot vacuum will have enough relative positioning information that it alone would be more than sufficient to pinpoint the target for a shooter, and do so with enough accuracy that there shouldn't be any visual penalties. And this should all more-or-less just happen, but it always seems fair to buy a tacnet to make it official-ish. But as a GM, I would present no penalties to indirect shooting this way; anyone who's seen Photosynth knows it's easily possible to seamlessly present visual information from different sources, and do so with very high accuracy, using only visual data to provide relative positioning. I envision "Captain's Chair" mode [no longer applicable, per se], or tacnets, as being very like a real-time Photosynth cloud.

For that matter, it's also trivial to calculate travel times such that you can punch a hole in a wall with one type of munition and follow it with something else entirely, from some other source. There's no reason you can't place a missile, a mortar shell, a sniper rifle round, and a laser beam, all on the same target, with arbitrary timing.

Big point here... didn't any one else note that the video systems are described as trideo cameras in the BBB? (at least the non micro versions)

That implies that the cameras are already binocular granting true 3d already without needing lots of extra sensors.

That's a really interesting point. Given the profusion of 3D devices we've seen in recent years due to the barest whiff of interest on the parts of consumers - including 3D cameras on smartphones and 3D handheld gaming systems for children - the market penetration when you've got free-standing holographic projection would be pretty total. In theory, every such camera would have the ability to rangefind all on its own, although perhaps not with extraordinary accuracy over great distances.

Not really looked into it, but i think the accuracy over distance depends on the distance between the sensors themselves.

Absolutely correct, as a general rule.

http://xkcd.com/941/