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Hello, I use the ununtu and openni.

I'm looking at the kinect depth value.

(http://www.ros.org/wiki/kinect_calibration/technical).

There is "Disparity to depth relationship".

Is it open-kinect or openni or both relationship?

I want to know depth value and compare the actual distance.

(http://mathnathan.com/2011/02/depthvsdistance/)

The hompage' host used libfreenect driver.

Can anyone tell me how to obtain depth value or disparity value in ubuntu, openni

driver?

Is it possible extract the distance or disparity in a particular point ?

Thanks.

I appreciate it. I read answers and look here(http://www.ros.org/wiki/cv_bridge/Tutorials/UsingCvBridgeToConvertBetweenROSImagesAndOpenCVImages)

There is "ROS passes around images in its own sensor_msgs/Image message format."

But "sensor_msgs/Image message format" has uint8[] data.(http://ros.org/doc/api/sensor_msgs/html/msg/Image.html)

Is it wrong? I know depth data is 11bit data. I think "sensor_msgs/Image" is encoded and it loss some information.

It convert ROS image to OpenCV image.

Loss image converted also has loss information. Is it right?

So I want to get 11bit raw datas. What can I do?

ROS passes around images in its own sensor_msgs/image message format. But it is 8bit data. So I wiil want to use images in conhunction with OpenCV. CvBridge is a ROS library that provides an interface between ROS and OpenCV. Maybe Using cv_bridge is 32bit data. Dose from 8bit to 32bit make loss accuracy?

I think sensor_msgs/image message format is 8bit and using cv_bridge is 16bit or 32bit. Dose from 8bit to 32bit make loss accuracy?

If I use cv_bridge, can I get depth or disparity value?

( I don't read last question. so I ask one more. you understand it )

In openni, I think sensor_msgs encode data.

Because, rostopic echo /camera/depth/image and /camera/depth/disparity pulish not 16bit or 11bit, just 0~255.

I think the data is not actual depth data( distance )

I want to know depth value. But I don't know how to get the depth value.

I know the relation ( Z=fT/d ).

I think the fomula substituted raw data is right.

How can I get the raw kinect sensor data?

Or How can I get the actual depth value?

Kinec topic /camera/depth/image_raw is published just 8bit.

not 11bit.

I try to know distance.

Documentation states that

depth/image_raw (sensor_msgs/Image) Raw image from device. Contains uint16 depths in mm.

But I get is values one byte long, max of 255

What do I use topic to measure kinect distance?

How can I find depth?

I try to compare the actual distance with kinect data.

I want to measure 1m from object to kinect.

From the object, where do I measure up to the kinect?

kinect"s front? middle? back??

Thank you. I have a question.

Does pointcloud2 topic put actual distance??

I am using ubuntu 11.10.

I place the kinect toward white wall

and

rosrun image_view image_view image:=/camera/depth/image

I can see the depth image

But rostopic echo /camera/detph/image

put different numbers(datas).

How can I get the same datas?

And how can I find actual distance using openni driver?

I have a Question. pleaes tell me the answer~

kinect 3D data has the X,Y,Z coordinates.

Where is the X,Y,Z data's (0,0,0)?

kinect sensor? kinect lens?