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How to calibrate D435 RealSense depth camera to achieve 1 mm resolution

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3 comments

  • MartyG

    Hi Matthew, could you provide an RGB image of the scene that the camera is observing please, as this will help to identify any environmental factors or issues with objects / surfaces in the scene that may be reducing depth quality.  Thanks!

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  • Matthew

    We are imaging the railroad rails and frogs 

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  • MartyG

    Thanks very much for the RGB image, it is helpful.

     

     The camera will have difficulty capturing the depth of surfaces that are colored black or dark grey.  This is because it is a general physics principle (not specific to RealSense) that black or dark grey absorbs light and so makes it more difficult for depth cameras to read depth information from such surfaces.  The darker the color shade, the more light that is absorbed and so the less depth detail that the camera can obtain. 

     

    A scene that is majority dark grey or black will usually return al depth image that has little detail on it or has inaccurate depth values.  In this particular case though it likely helps that the dark surfaces in this scene have grain and texture (like the gravel and the rough wood surfaces), meaning that you should get at least some depth detail as textured surfaces provide more depth information for the camera.

     

    In such a scene, if you have not tried it already then the depth image may improve if you set the Laser Power option to its maximum value of '360' (it is '156' by default).  This is because maximizing Laser Power can make the invisible dot pattern projected by the camera onto surfaces easier for the camera to see by strengthening the visibility of the dots and so improve analysis of those surfaces for depth information.

     

    Casting an additional external light source onto the scene to illuminate the surfaces more strongly can also help to bring out depth detail from black / dark grey surfaces.

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