[ros-users] Stereo, distance measurement

[Homer Manalo]

Anyone knows how to get d(disparity) from the DisparityImage.msg?

On Wed, Feb 2, 2011 at 5:33 PM, Homer Manalo <homer.manalo at roboteknik.com>wrote:

> According to the documentation of DisparityImage.msg:
>
> http://www.ros.org/doc/api/stereo_msgs/html/msg/DisparityImage.html
>
> depth can be calculated by Z=fT/d, so far I can get the minimum distance:
>
>         distance = data.f*data.T/data.max_disparity
>     print "Minimum distance:", distance, "meters"
>
>         Minimum distance: 0.430558934726 meters
>
> How do you get d(disparity) here?
>
>
> On Wed, Feb 2, 2011 at 11:37 AM, Homer Manalo <homer.manalo at roboteknik.com
> > wrote:
>
>> Ok, so I need to manually extract this? Or is there a command to show this
>> up? Which one is it contained:
>>
>> [sensor_msgs/PointCloud2]:
>> Header header
>>   uint32 seq
>>   time stamp
>>   string frame_id
>> uint32 height
>> uint32 width
>> sensor_msgs/PointField[] fields
>>   uint8 INT8=1
>>   uint8 UINT8=2
>>   uint8 INT16=3
>>   uint8 UINT16=4
>>   uint8 INT32=5
>>   uint8 UINT32=6
>>   uint8 FLOAT32=7
>>   uint8 FLOAT64=8
>>   string name
>>   uint32 offset
>>   uint8 datatype
>>   uint32 count
>> bool is_bigendian
>> uint32 point_step
>> uint32 row_step
>> uint8[] data
>> bool is_dense
>>
>> [stereo_msgs/DisparityImage]:
>> Header header
>>   uint32 seq
>>   time stamp
>>   string frame_id
>> sensor_msgs/Image image
>>   Header header
>>     uint32 seq
>>     time stamp
>>     string frame_id
>>   uint32 height
>>   uint32 width
>>   string encoding
>>   uint8 is_bigendian
>>   uint32 step
>>   uint8[] data
>> float32 f
>> float32 T
>> sensor_msgs/RegionOfInterest valid_window
>>   uint32 x_offset
>>   uint32 y_offset
>>   uint32 height
>>   uint32 width
>> float32 min_disparity
>> float32 max_disparity
>> float32 delta_d
>>
>>
>> Thanks,
>> Homer
>>
>>
>> On Wed, Feb 2, 2011 at 11:17 AM, Daniel Maturana <dimatura at gmail.com>wrote:
>>
>>> Both the the disparity and the points2 messages have the information
>>> you need. Note that your camera should be calibrated.
>>> best,
>>> Daniel
>>>
>>> On Tue, Feb 1, 2011 at 8:13 PM, Homer Manalo
>>> <homer.manalo at roboteknik.com> wrote:
>>> > I've actually used it for viewing disparity and rectifying images. What
>>> > topic exactly are you referring to?
>>> >
>>> > Homer
>>> >
>>> > On Tue, Feb 1, 2011 at 11:43 PM, Daniel Maturana <dimatura at gmail.com>
>>> wrote:
>>> >>
>>> >> Try http://www.ros.org/wiki/stereo_image_proc.
>>> >> Daniel
>>> >>
>>> >> On Tue, Feb 1, 2011 at 4:13 AM, Homer Manalo
>>> >> <homer.manalo at roboteknik.com> wrote:
>>> >> > Are there packages that convert stereo data into real world
>>> measurements
>>> >> > -
>>> >> > how far an object is from camera?
>>> >> >
>>> >> > Thanks,
>>> >> > Homer
>>> >> >
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>>> >> >
>>> >> >
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>>> >
>>>
>>
>>
>
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