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Measure the white resin plate with L515

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6 comments

  • Aznie Syaarriehaah

    Hi Isnida,
    The L515 uses reflected light to calculate the distance of objects. If the reflected light is too strong, the receiver will saturate in the same way that a camera image can be overexposed. Oversaturating the receiver makes it impossible for the system to get any useful information resulting in poor or no depth. Conversely, if the reflected light is too weak, the system is unable to get useful information resulting in poor or no depth. You have control of the laser power and can adjust if necessary. It is recommended to start with the presets as these are designed to cover most situations. Meanwhile, could you please share the screenshot of your issues and also your RealSense Viewer preset settings for us to have a better understanding regarding this.

    Regards,
    Aznie
    Intel RealSense Customer Support

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  • Ishida

    Hi Aznie,

    Thank you for your advice.

    I adjusted the laser power and gain.

    But the result did not change.

    I found an interesting phenomenon during the test.

    When I put a clear acrylic board on the table, the table dents.

    When I put an 8mm acrylic board, it dents about 4mm.
    When I put a 3mm acrylic board, it dents about 1mm.

    As a result of calculating the optical path length with the refractive index of acrylic (1.49), it is approximately the correct value.

    Also, when I looked at the IR camera image of the polyacetal plate, it was translucent.

    I think that substances that look transparent in the infrared band need attention.

    Is my reasoning correct?

    Thank you.

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  • Aznie Syaarriehaah

    Hi Isnida,

    The phenomenon is due to the reflectivity and IR absorption properties of the resin. The Intel® RealSense™ LiDAR Camera L515 User Guide discusses how reflectivity affects results.

     

    Regards,

    Aznie

    Intel RealSense Customer Support

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  • Ishida

    Hello Aznie,
    Thank you for your advice.
    A similar phenomenon was posted in Figure 19 on page 19 of the User Guide.
    I understand that transparent objects like glass allow IR to pass through and measure wall distances. (Actually, the distance will be longer by the refractive index of the glass)
    I can see an interesting phenomenon in this picture.
    It's the wine distance.
    In the image, the wine is in front of the hand. However, the color of the color contour is farther than the hand.
    This phenomenon is the same as the color contour of polyacetal in the above image.
    What is the mechanism by which distance increases in the case of translucent substances such as wine and polyacetal?

    Thank you.

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  • Aznie Syaarriehaah

    Hi Ishida,
    As the caption explains, transparent objects do not reflect the light back into the camera receiver. While the wine is not completely transparent, it does not reflect the light as well as the hand reflects the light.

    Regards,
    Aznie
    Intel RealSense Customer Support

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  • Ishida

    Hello Aznie,
    Thank you for your advice.

    I have reserchde many treatises.

    As a result, I found the cause of the measurement error.

    The cause is scattered light generated inside the translucent body.
    The reflected light from the surface of the translucent body and the scattered light from the inside are mixed, and as a result, the distance appears far.
    This phenomenon is a characteristic of ToF cameras.
    The measurement results of ketchup and mayonnaise in the treatises are shown in the image below.
    Thank you for everything.

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