Sensing area dimensions and environment recommendation

[le_joe]

I'm looking for documentation on the area of sensing of the Leap Motion. I have looked into the SDK docs, but the area is not precisely defined.
What are the dimensions of the area ? I found this picture, but it's not official. Can you confirm this ?
What are the recommendation regarding the environment ? What could lead to bad recognition ? I know that there must not be direct light above the device, what about another Leap Motion at about 1m nearby ? Is it sensible to IR light ? Can I mount it behind glass ?

[jlkingiii]

The graphic looks about right. It is stated to be 8 cubic feet, but it can detect motion a little past that, just not as reliable. So a meter away might work if it is just very simple large gestures you want to detect, but it seems a bit far. Glass should be fine. The glass will typically filter about 10% of the IR light, so it will reduce the field just a tad. The Leap Motion has surprisingly good filters, but yes IR light will mess with it.

[RuZman]

Can I mount it behind glass ?

It is possible, but difficult and not recommended. I tried to use the Leap Motion behind glas (1cm). There is only a very small area perceived (~10x10x10cm) and as you can see, it loses the hand very often.

[AlexColgan]

The image is from our developer marketing assets and is official

https://developer.leapmotion.com/downloads/developer-marketing-assets

The issue with mounting behind glass is that any refraction or distortion of the light will result in a loss of tracking precision, as the device (and the mathematics underlying it) are highly specialized.

[le_joe]

Thanks. What would be your advice for a protection above the Leap Motion ? I want to find a way to forbid people to touch it.

[AlexColgan]

A very thin sheet of acrylic glass would do the trick, though I have to stress that this may result in performance and accuracy issues. A lot of it depends on the lighting environment, which can cause false positives or other tracking issues if light were reflected off the pane. Smudges and scratches on the acrylic would also further detract from tracking quality.

Ultimately, accuracy takes a hit when you place something between the hands and the device. Is it worth it? For your purposes, it depends on the distance of the interaction zone that you intend to use, the environmental lighting factors, and your priorities in the design of the installation.