How do I use RegionOfInterest in sensor_msgs ?

asked 2012-02-20 10:12:16 -0500

samesimasemsom
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updated 2014-01-28 17:11:24 -0500

ngrennan
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Hey everyone,

I'm using the kinect and Openni_launch to publish a pointcloud (pcl::point<xyz>). I want to extract the distance of a point given the pixel coordinates of that point.

so lets say, in the 640x480 pixel matrix, I want to extract the depth at cell 100x100. I thought of using sensor_msgs::PointCloud2 and sensor_msgs::RegionOfInterest. But I can't find out how to make them work together.

I currently have:

void roiing(sensor_msgs::RegionOfInterest roi) { roi.x_offset = 100; roi.y_offset = 100; roi.height = 1; roi.width = 1; roi.do_rectify = false; }

and then some Functions to subscribe to topics and do processing..

The region of interest doesn't change anything and I was wondering how I can make it work ? I can't find any code online where the RegionOfInterest message is used.

Thanks

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answered 2012-02-20 11:34:50 -0500

Dan Lazewatsky
9115 ●79 ●103 ●160 http://dan.lazewatsky.com/

Is there somewhere specific that tells you to use a RegionOfInterest message? You can access a specific point from an organized pointcloud (which the openni driver produces) by using cloud.at(u,v).

Alternatively, if you just want the depth, you can subscribe to the depth image, and just index into the image, which will provide you with the depth.

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answered 2012-02-20 12:48:38 -0500

samesimasemsom
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updated 2012-02-20 12:49:25 -0500

Thanks for you response, I was looking for such a function for days!

Alternatively, if you just want the depth, you can subscribe to the depth image, and just index into the image, which will provide you with the depth.

referring to the sensor_msgs::Image doc : http://www.ros.org/doc/api/sensor_msgs/html/msg/Image.html

How do I index the image ?