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Openni_Kinect Module
Subbu from United States  [21 posts]
5 years
Hello All,
             We recently purchased robo realm. I am using the OpenNI_Kinect module with ASUS Xtion Pro Live. It works fine. But I want to extract the depth value of the middle pixel and write them on a text file along with frame information as given by the "NiSimpleRead" OpenNI code. So is there a way to do it at the moment. Or is it a new feature that has not been incorporated yet.

Thanks,
Subbu
Subbu from United States  [21 posts] 5 years
Any help please?
Anonymous 5 years
Subbu,

You should be able to use the Sample_Color module to define the inner part of the image and get its average value. I'd recommend NOT getting just the center pixel as that can be noisy. Getting a 16x16 size area will help to reduce noise.

See

http://www.roborealm.com/help/Sample_Color.php

for info on that module. It will produce a

COLOR_SAMPLE_RGB

variable that can then be written to a file using

http://www.roborealm.com/help/Write_Variables.php

Hopefully that helps.

STeven.
Subbu from United States  [21 posts] 5 years
Thanks for the reply Steven. Well, one of the aims of my project is to track the Depth Information as we will be using a pendulum that moves towards and away from the Xtion Pro Live Camera. In that case, we need the depth information to track the difference between the extreme ends which is a useful data for us.

Hence I dont think Sample Color could be a suitable option at the moment. Is is possible to add this feature to give us the Depth Data (Z Axis Values in real time) within the OpenNI Kinect module as a variable so that we can write to a file and analyze it?

Thanks,
Subbu
Anonymous 5 years
Subbu,

You could use the known size of the red object to determine distance. The size of the blob is proportional to the distance of the object. But you'd also have to be sure to calibrate the camera image correctly ... so if you can get away with using the Asus then I'd just stick with that.

The ASUS produces depth information at a 12 bit number. The module represents that as a pixel itensity. So the sample_color module will give you an average pixel intensity which can then be converted to actual distance using the information from this post (last entry)

http://www.roborealm.com/forum/index.php?thread_id=3865#

STeven.

Subbu from United States  [21 posts] 5 years
Well, the object that I currently used with the pendulum is a test object. I am required to use different colored object with unknown sizes for the bob of the pendulum.

And I was requesting for the feature addition because just like in the program NISimpleRead, If I can get the depth value of the middle point, then I can use it directly when I experiment on the pendulum when it is moving towards and away from the camera.
Anonymous 5 years
I've merged the responses to this with

http://www.roborealm.com/forum/index.php?thread_id=4537

STeven.

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