Got the tablet two days ago and played it for a while... Project Tango utilizes IR depth sensor to obtain the distance of different objects (and possibly the resulting image is a combined work with fisheye camera). My assumption is they use camera to do some imaging processing to find out rough edges of different objects, and then use the depth sensor to get distance info. And to be honest, it is just a big toy when things work like they should.
- The range setting is just weird but reasonable. Given the limited power of such a device and transceiver characteristics, it is hard to achieve further distance than 4m. Well, maybe, just maybe they could argue that for indoor environment this is already good enough. Even if within the range between 0.5m and 4m, the device does not guarantee the working status, i.e. it'll fail in finding many things in the scene.
- Environment conditions are very limited. From Project Tango's webpage, it was saying that "the depth sensor cannot detect very dark, shiny, and transparent materials." Based on what I tried, this means it does not work when there is no light, or too much light, or things that have very strong reflections, or very weak reflections. Hmm.. Although under expectation (physics), I was hoping they come up with ideas better than this.
- And obviously this device is still under development since drivers crash frequently. You first open up the app "Project Tango Explorer" and try to understand what is going on, and it might give the error message. Something like "failed to connect to the hardware."
I am disappointed in this device mainly because I had such a big expectation as the device comes from Google and a research group in my undergraduate school. From my understandings of imaging, we should be able to do way better than this. Looking forward to better experience in near future.
Oh, of course, they have a so-called "Area Learning" feature, which initializes the location of your device and is able to show your relative position while you move the device. Nothing new but accelerometer, gyroscope, etc. Will upload some images later on.