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How to find the pose of a pattern

asked 2018-06-27 05:33:27 -0500

Bwaki gravatar image

updated 2018-06-27 07:39:29 -0500


I a currently working an a project and i need to find the pose of a pattern this one for example :link text i know that some calibration package use the pose to calibrate the camera but i don't know how they do it.

Thanks you in advance.

PS: i am on Ubuntu 16.04 with ROS Kinetic


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what do you mean by "pose of the pattern"? In relation to what? Where on the pattern? Please be more specific.

mgruhler gravatar imagemgruhler ( 2018-06-27 07:16:08 -0500 )edit

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answered 2018-06-28 05:47:17 -0500

Okay, this is a fairly standard operation. In order to do this you'll need to know the dimensions of the pattern you're detecting and the calibration parameters of camera lens you are using. Using these two sets of information it is possible to determine the 6 DOF pose of the pattern with respect to the optical frame of the camera.

Firstly you'll need to calibrate your camera using the instructions described here, these calibration parameters allow you to determine the exact direction that each pixel of the camera image is facing.

Now you should be able to receive camera images and their camera info parameters, which allows you to do all sorts of clever things with OpenCV. You'll need to use two functions from the calibration and reconstruction module.

1) The findCirclesGrid function can be used to detect the location of the patterns circles in image space. If successful this returns the 2D locations of the centre of each circle in pixels.

2) Next the solvePnP function can be used with the circle points and the known size of the pattern to determine it's pose.

When defining the size of the pattern you assign each circle a 3D location in meters, the coordinate system used here defines the coordinate system of the pose that is produced.

Hope this gets you started.

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Thanks you very much it is exactly what i wanted to do ^^

Bwaki gravatar imageBwaki ( 2018-06-28 05:53:03 -0500 )edit

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Asked: 2018-06-27 05:33:27 -0500

Seen: 147 times

Last updated: Jun 28 '18