Advices about finding pointing of a bottle with opencv

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The drawback of this approach is that you only get the direction without a sign, so another step is needed. I'd propose to use the angle of the main Axis and to rotate the image so that you have an image of the bottle upright (or upside down). You then check the topmost and lowest columns and compute the horizontal variance of the white pixels. The variance at the bottom of the image will be much larger and you are able to tell in which direction your bottle is pointing.

Indeed, getting the orientation is indeed the second part of the problem :D But I guess that getting the overal direction is already quite challenging for TS.

If you have the direction and the midpoint of the contour, you can split the contour into 2 parts (on the "left" and "right") relative to the midpoint and in the found direction, and compute the area of the 2 contours. The one that has the smallest area is the top of the bottle, so that is the pointing direction of your bottle. Maybe it is not the best, but is an idea of continuation.

Actually it is a quite good solution which will work just fine here :)

Hey, thanks for all of the ideas. You are awesome guys. I will keep asking here because this is my first approach, later I will have to cope with several objects (identify them) and also to use several multicolored backgrounds and so on. But for now it's really good.