Just remembered there is a product on the market that is a see-through capacitive touch matrix that will fit behind glass, one of my colleagues sourced this and it works fairly well behind a thick pane of glass (probably over a centimetre) and functions alongside a screen placed behind it as a fairly reliable touch screen with acceptable resolution. 

I will try and dig out the brand if it is appropriate for your use. 

Sent from my iPhone

> On 29 Sep 2015, at 14:35, Chris King <[log in to unmask]> wrote:
> 
> Thinking about this, capacitive might be the way to go as it can probably reach through glass and there shouldn't be any stray or variable background "noise" as there may be with optical/ir, I am sure I have seen projects along these lines before and have messed with simple capacitive sensors working behind a few mill of wood, then as Andrew says the makey makey is a great way to get button presses out from any kind of input, you can also run similar code on any Arduino with the same result. 
> 
> Best
> 
> Chris
> 
> 
> Sent from my iPhone
> 
>> On 29 Sep 2015, at 14:12, Andrew Lewis <[log in to unmask]> wrote:
>> 
>> Hi Danny,
>> 
>> 
>> 
>> One way that this can be done is with proximity sensors hooked up to a Makey Makey (possibly need a separate Arduino too)
>> 
>> 
>> 
>> You could make hot spots  within areas of the window display by effectively having the sensors point out through the glass and if something comes close enough (e.g. a few centimetres from glad max) the proximity signal is triggered.
>> 
>> 
>> 
>> You might need to scale it to be a logical off or on (0v or 5V), but with a Makey Makey, that translates to button presses, or mouse clicks, etc.
>> 
>> 
>> 
>> Your software then just needs to know how to handle the button presses/clicks
>> 
>> 
>> 
>> Probably easily doable all on a Raspberry Pi with a Pi-Face sensor board too.
>> 
>> 
>> 
>> The only thing you'd need to check is the sensor type:
>> 
>> 
>> 
>> Not all Infra-red will go through glass as it is low energy (this is why greenhouses get hot light comes in, heat can get out) - some may
>> 
>> Ultrasonics - not sure that would work either for same sort of reason
>> 
>> Photoresistors could work, but need to work out the ambient lighting. If in a daylight area, should be easy, but at night if the level is low, it might not work.
>> 
>> 
>> 
>> Have fun with that one!
>> 
>> 
>> 
>> 
>> 
>> Date:    Mon, 28 Sep 2015 11:00:52 +0000
>> 
>> From:    "Birchall, Danny" <[log in to unmask]<mailto:[log in to unmask]>>
>> 
>> Subject: Kinect / windows
>> 
>> 
>> 
>> Hi all
>> 
>> 
>> 
>> I've got a physical-interaction technology question; I'm hoping some of you might be able to help me with some experience or recommendations....
>> 
>> 
>> 
>> We're working on a large display of printed images in a window facing a public street, which we would like to make interactive by allowing the public to vote for their favourite image, from outside in the street. We've explored touchscreens (but the window glass is very thick), and we're thinking that an easier way to achieve this might be through something like a Kinect.
>> 
>> 
>> 
>> The device would need to be able to recognise clear gestures of someone selecting an image (perhaps by touching vinyl stickers placed on the window in front of each image) and then recording the data.
>> 
>> 
>> 
>> Does anybody have any experience with developing thigs like this, any thoughts about potential pitfalls (dark street, light windows, traffic nearby) and/or development costs?
>> 
>> 
>> 
>> Thanks in advance for any pointers.
>> 
>> 
>> 
>> Danny
>> 
>> 
>> 
>> 
>> 
>> Danny Birchall
>> 
>> Digital Manager, Wellcome Collection
>> 
>> 
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