BTW:
The patent for the Primesense reference design (which contains a
chapter on image registration) is available here:
http://www.google.com/patents?id=k3vLAAAAEBAJ
There, 12 coefficients of a parabolic fit for registration are
calibrated in advance. So originally, registration was supposed to
happen on the Kinect device, a downgrade during development might has
resulted in this no more being the case (or that stuff is still in
there and not used).

2010/11/16 Tully Foote <tfoote@willowgarage.com>:
> Hi Stéphane
>
>>
>> 1. Having multiple implementations of Kinect ROS nodes is not harmful as
>> we happily share code. However, to ease the end-user's life I think that
>> we should agree on a naming convention for node and topic naming. Here
>> is a first suggestion:
>>   node name: "kinect"
>>   point cloud frame: "/kinect"
>>   point could topic: "/kinect/cloud" (PointCloud + color in "rgb")
>>   rgb image topic: "/kinect/image" (Image, rgb)
>>   depth (raw in 8bpp) image topic: "/kinect/depth_image" (Image, mono8)
>>   accelerometer topic: "/kinect/acc" (Vector3)
>>   tilt input: "/kinect/tilt" (Int16)
>> Feel free to discuss it and propose more conventions, for instance for
>> the params/etc.
>
> While things are rapidly developing and different approaches are being tried
> out multiple drivers are not harmful and potentially are beneficial as
> people are exploring how to interface with the device.  Unless there are
> irreconcilable differences it makes sense in the long run for them to
> merge.  A few of these differences might be licensing and dependency
> requirements.  However with the scope of the Kinect device I expect that
> these can be resolved to everyone's satisfaction.
>
> I agree that finding a common API for the device will make everyone life
> easier.  There's also the ccny API documented at
> http://www.ros.org/wiki/kinect_node  They have laid out a few parameters in
> addition to a very similar set of topics.
>
> The most important aspect of making life easy for end-users as well as
> developers is documentation.
>
> It's awesome to see the Kinect driver useable so quickly, keep up the great
> work everyone.
> Tully
>
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