[ros-users] FYI Kinect hacked driver for linux

Alex Trevor atrevor at gmail.com
Fri Nov 12 07:24:49 UTC 2010

Apologies for the broken github link, the correct one is:

On Fri, Nov 12, 2010 at 2:20 AM, Alex Trevor <atrevor at gmail.com> wrote:

> Wow, looks like quite a few people are working on kinect nodes; we should
> probably combine efforts!  We’ve also been working on a kinect node for ROS
> based on Hector Martin’s driver, available at:
> git://github.com/atrevor/kinect_node.git<https://docs.google.com/document/d/1R0OpKD-3StR78uk1-jCrcoZ9U9EX0eT3XSantF6jMg8/edit?hl=en&pli=1>
> Short youtube rviz screencap:
> http://www.youtube.com/watch?v=IxRIL1izvDs
> We assume that you have libfreenect from Hector Martin’s repo in the same
> parent directory (../libfreenect w.r.t. kinect_node):
> git://git.marcansoft.com/libfreenect.git<https://docs.google.com/document/d/1R0OpKD-3StR78uk1-jCrcoZ9U9EX0eT3XSantF6jMg8/edit?hl=en&pli=1>
> So far, it publishes the camera image, as well as a PointCloud2 of
> PointXYZRGBs.  The RGB camera’s image is projected onto the range data,
> resulting in a color point cloud.  We calibrated the RGB camera, but haven’t
> yet calibrated the range camera -- since we can’t just use our normal
> checkerboard calibration target for this :) .  As Ivan and Stefan noted, the
> ranges we get are a little odd -- they definitely don't seem to be linear.
>  We calibrated it so the range is approximately correct at 2m for our
> sensor, but I agree that we really need to know how these work to make much
> progress. We'll probably do some testing shortly with targets at various
> ranges to attempt to address this.  Any input would be greatly appreciated!
> On Thu, Nov 11, 2010 at 5:41 PM, Stefan Kohlbrecher <
> stefan.kohlbrecher at googlemail.com> wrote:
>> > 1. Is the depth image really 640x480, or is that oversampled? The
>> > wikipedia page states the depth sensor has an resolution of 320×240
>> > pixels. If it's oversampled, where does that take place - in the
>> > driver, or the device itself? I prefer not inflating the point cloud
>> > with oversampled data
>> I think the device itself reports the data with this size. If you look
>> at the picture I posted in the second post you also see that there are
>> for example one pixel sized holes in the 640x480 sized depth image,
>> which should not exist if some very simple interpolation scheme would
>> be used to blow up a 320x240 image to 640x480.
>> From what I read beforehand, the original Project Natal was supposed
>> to be 640x480, then Microsoft reportedly "downgraded" to 320x240 for
>> cost reasons (see
>> http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=kinect+downgraded+to+320x240
>> ).
>> Now the sensor appears to deliver 640x480 again, which might or might
>> not be just blown up 320x240on the onboard ASIC.
>> > 2. What is the relationship between the values in the depth_frame and
>> > the distance in meters? It doesn't appear to be linear
>> That´s really the interesting question, along with others like how to
>> calibrate visual and depth image to get real RGB-D data. With the
>> current state of affairs one can generate some impressive looking
>> images, but to leverage the full potential of the sensor these
>> calibration questions really have to be solved.
>> > 3. I read somewhere the device's range can be set dynamically. I'm
>> > guessing one of the inits in inits.c could be responsible for the
>> > range.
>> That´s more stuff that will probably be discovered in the coming
>> days/weeks. Still very impressive how good the sensor works already
>> right out of the box.
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