Quick heads-up regarding the nuitrack SDK - I created a Cinder block (c++) which was polling the SDK for tracked skeletons. In spite of the poor documentation I got a working boxman demo going with the Astra on Windows, tracking multiple skeletons simultanously. It reported some strange joint orientations when limbs where out of view but it seemed like I could work around that (especially since at the moment I only need to track the head position of my users).
Unfortunately after testing for a longer period of time a crash occurred in a specific situation. As far as I can see, if a single user is being tracked for a longer period of time (minutes) at some point the skeleton data will freeze. As soon as that user steps out of the tracking frame the nuitrack SDK crashes and burns. I got an opencv error message, something to do with resizing an empty frame I believe, but since the SDK is closed source I figured it wasn't worth investigating further.
Also, about 80% of the nuitrack forum posts is Russian spam. That is an accurate description of the level of support and documentation you can expect.
Edit: to be completely fair the technical API documentation isn't too bad and can be found here
I had to abandon Orbbec for potential licensing issues and I had to abandon the Astra + nuitrack SDK because of the crash(es). All in all not a very good experience and currently forced to keep using the Kinect, which is getting harder and harder to purchase. I saw the Kinect for Windows going for $500 on Amazon recently.
I understand there is a rush to fill the gap in the market left behind by Kinect but please keep in mind you are making these products for developers. It would be so helpful for all of your customers if there is extensive and clear documentation, including example applications for each supported platform, showing off both the core SDK and the body tracking SDK.
Most importantly, like I said before the current licensing situation forces me to abandon this product and it does not give me a lot of trust in Orbbec as a serious competitor in this field. If the situation changes I might give it another try but I will be very skeptical as I feel I've wasted a couple days trying to find a long term solution for body tracking.
If anyone wants to give the nuitrack block a try I put it up on GitHub. I am curious to hear if any of you have different experiences.