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the position of the detected object is not correct!!

asked 2022-05-25 13:40:41 -0500

Delbina gravatar image

hi,

after launching find_3d_object.launch, i can see that the position of the detected object is not correct: in the following you can see one example. i have considered camera_color_optical_frame as the fixed frame. so i expect that the objects on the right hand side of my camera have a positive x and negative y, and positive for both x and y for those objects on the left side. but you can see that for the objects in the left side, both x and y are negative? why? i have considered: X forward Y left Z up

one more thing is that we expect by the movement of the vehicle toward objects, distance between them decrease, but the output sometime is increase and sometimes decrease.!!!!

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object_44 in the left sie, this is the plot about x position over time, from the time that it has been detected, and up to the time that the object disappear from the point of view of camera (vehicle is moving on the railway track)

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object on the right hand.

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answered 2022-09-05 23:34:27 -0500

matlabbe gravatar image

The object position is in camera optical frame as stated in the terminal, so x->right, y->down, z->forward. So if you are looking X, as you move towards the objects: for object on left of the track, X will decrease over time (appear going left of the image); for object on right of the track, X will increase over time (appear going right of the image).

The position is relative the center of the lens, so X is negative if left side and positive on right side of the image. For Y, it is negative if appearing over the center and positive if appearing below the center.

If you are interested in distance instead, watch the Z value instead. There could be variation depending of the noise of the disparity image computed by your stereo camera.

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Asked: 2022-05-25 13:40:41 -0500

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Last updated: Sep 05 '22