L515 control angles through code

• Aznie Syaarriehaah

  • September 17, 2021 13:50

  Hi Ivan Deboi,
  There is no tools or script to implement that, but there is an example for extracting the IMU data you can refer to that might be a help for you. For the L515 LiDAR camera, the IMU data is stored in different frames, similar to how Depth and RGB streams data are stored in frames. The IMU framerate for the L515 is 100 fps. Look at this code sample for accessing the acceleration and gyro data.
  
  Meanwhile, the IMU of the L515 camera does not provide orientation data, also known as Pose. The IMU of the L515 only provides angular velocity, accessed as gyro, and angular acceleration, accessed as accel.
  
  Regards,
  Aznie
  Intel RealSense Customer Support

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• Ivan Deboi

  • September 20, 2021 12:46

  Hi Aznie,

  To be clear, I don't need the angles of the device itself, but the angles of the laser beam with respect to the device. 

  Please have a look at https://www.youtube.com/watch?v=Vv0VielKRes&ab_channel=IntelRealSense around timestamp 2:28. The lasers moves up down and left right. From the curvy pattern, I can tell that the left right angle is kept constant when then laser goes up down. It makes a pattern like this: https://www.semanticscholar.org/paper/A-Mathematical-Model-and-Calibration-Procedure-for-Manakov-Seidel/bb0086723a5018ac45a306390d441c59ae82edd4 This is NOT a perfect 2D equidistant grid like a checkerboard or something. For my research, which revolves around high accuracy calibration, I need those laser angles (or the parameters that control them, could be voltages).

  Kind regards, Ivan

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• Aznie Syaarriehaah

  • September 21, 2021 01:39

   

  Hi Ivan Deboi,

   

  The L515 Camera uses LiDAR technology to measure the distance from the camera to the object. Similar to other LiDAR systems, the L515 sends a laser beam and measures the returned time of the reflected light off an object. The L515 accomplishes this using a continuous coded IR beam. The time taken for the light to return to the camera is used to calculate the distance of the object. By repeating this process millions of times a second, the L515 is able to build a high-resolution depth map of the scene. 

   

  L515 creates a depth frame by scanning the scene with millions of points of information per second. Thus, it is impossible to know or measure the angles of the reflection since it will depend on the reflective surface.

   

  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. After you are familiar with the effect of the presets, adjusting the laser power manually may give better results considering the specific distance and objects for the use case. The laser power can always be set back to default if needed.

   

  Regards,

  Aznie

  Intel RealSense Customer Support

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• Ivan Deboi

  • September 21, 2021 10:08

  Hi Aznie,

  Your device stills need to know the IR beams orientation (and thus angles) to calculate a 3D coordinate of a point where a reflection occurred. Not just a distance. 

  How does the "continuous coded IR beam" work? Do we have access to to how the beam is controlled? Can we read the values that are used to control the beam? 

  Kind regards,

  Ivan

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• Aznie Syaarriehaah

  • October 01, 2021 03:11

  Hi Ivan Deboi,

  1.How does the "continuous coded IR beam" work?

  The working principle is explained in the video below (14:00):

  Introduction to Intel RealSense LiDAR Camera L515

   

  You can also refer to the paper below for additional information:

  Optimizing the Intel RealSense LiDAR Camera L515 Range : 

   

  2. Do we have access to how the beam is controlled? Can we read the values that are used to control the beam?

  How the beam is controlled cannot be accessed, nor can we read the values that are used to control the beam. 

   

  Regards,

  Aznie

  Intel RealSense Customer Support

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