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D405 Scene Integrated Issues

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3 comments

  • MartyG

    Hi Conor Mckenna  The D405 camera model is not equipped with an infrared dot pattern projector component like other models in the RealSense 400 Series are, so smooth plain surfaces can be difficult for the D405 to analyze for depth information.  This is because the dot pattern that a projector casts over the surface of objects provides the surface with a texture for the camera to analyze.

     

    An external visible pattern projector could be used to project a pattern onto an object's surface.  It has to be a visible pattern projector because the D405's sensors are equipped with IR-Cut filters that exclude infrared frequencies from the camera's perception and only allow visible light frequencies to be seen.  The section of Intel's guide to use of projectors with 400 Series cameras linked to below has information about visible pattern projectors.

    https://dev.intelrealsense.com/docs/projectors

     

    If the surface of the metal is not highly reflective then you could alternatively try casting a strong light source onto it to help to bring out depth detail from a smooth surface.  This is because 400 Series cameras can use ambient light in a scene for depth analysis instead of the infrared dot pattern projection.

     

    Another possibility is to use a fine spray-on powder such as baby powder or foot powder on the metal object's surface to dampen reflections and give the surface some texture.  There are also professional 3D scanning aerosol sprays that can dampen reflections from metals.

     

    Glare from reflections on surfaces also make a surface more difficult for a camera to depth-sense.  Applying a physical linear polarization filter product over the lenses on the outside of the camera can significantly dampen glare from reflections and therefore enhance the image.   Any polarization filter that is linear will work (except for the circular ones used in 3D glasses) and so such filters are inexpensive to purchase.  You can search stores such as Amazon for the term linear polarizing filter sheet for examples of such filter products.

     

    Section 4.4 When to use polarizers and waveplates of Intel's guide to use of optical filter products with 400 Series cameras provides more information about use of linear polarization filters.

    https://dev.intelrealsense.com/docs/optical-filters-for-intel-realsense-depth-cameras-d400#4-the-use-of-optical-filters

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  • MartyG

    If Open3D is not a compulsory requirement of your project then you could explore using the free open-source 3D tool MeshLab to import your ply, convert it to a mesh and edit it.  A guide for doing so with the Viewer and MeshLab is here:

    https://www.andreasjakl.com/capturing-3d-point-cloud-intel-realsense-converting-mesh-meshlab/

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  • Conor Mckenna

    Hi Marty! Thank you for the thoughtful response! I will be looking into and exploring your suggestions more tomorrow. Even on my first read through though, you have given me lots to think about. Thanks again!

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