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D455 the coordinate system

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5 comments

  • Zahid Iqbal

    I attach the following diagram with reference to the above question.

    thanks,

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  • Zahid Iqbal

    by mistake, I inserted several times.

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  • MartyG

    Hi Zahid Iqbal  The D455 camera model uses the same coordinate system as the D435i, described at the link below.

    https://github.com/IntelRealSense/librealsense/blob/master/doc/d435i.md#sensor-origin-and-coordinate-system

     

    RealSense sensors use the perspective of a person standing behind the camera looking forwards, like a person's eyes looking forward at the real world.  This is why when the camera is viewed from the front, the left infrared sensor is on the right side of the camera.

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  • Zahid Iqbal

    this means, +ve x-axis should be on the other side?

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  • MartyG

    There is an easier way to visualize how the coordinate system works.  Depth and RGB color each have their own separate 3D coordinate systems.  In these systems, the positive x-axis points to the right, the positive y-axis points down, and the positive z-axis points forward. 

     

    Whether the X and Y coordinates are positive or negative depends on whether a coordinate is to the left or right of the center-line of the sensor (X), or above or below the center-line of the sensor (Y).  

     

    So if a coordinate on the image is in the top left area of the RGB image then you could say that its Y coordinate value is a minus value (because it is above the RGB sensor's centerline) and its X value is a minus value (because it is to the left of the RGB sensor's centerline).

     

    It is a somewhat difficult subject, and one that usually does not have to be thought about at all when creating RealSense applications.  I believe that the confusion may stem from the above diagrams being viewed from the front-of-camera perspective, when the camera actually uses the 'standing behind the camera' perspective.  So when viewing from behind looking forward, what is positioned horizontally right on the front of the camera becomes left.

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