D435i Depth Camera - Obtaining IMU data using Matlab

Hello, I am trying to obtain the IMU data from the D435i depth camera in order to figure out the rotating angle of the depth camera. I have seen the examples in Intel Realsense github but am unsure how to enable the accelerometer and gyroscope stream to obtain this.

https://github.com/IntelRealSense/librealsense/tree/development/wrappers/matlab

The capture_example.m seems to be an app that shows this data in real-time but I simply want to be able to read the gyro and accelerometer values off so I can use it as a basic function that prints these values in the command window. From what I see in the app they designed an interface and the primarily functions that calculate the gyroscope and accelerometer values are function set_motion_data(app,h,d) and function h = draw_motion_data(app,ag,at,d,ss), the other functions are mostly used for start up and app interface I believe. I think the set_motion function has the equations I require to do this but not sure how to extract them outside of the app.

Any help is appreciated thank you! I do know that the camera is required to run the example but even some

Answer 1

[Suraj]

Greetings Jian-Hong,

I understand that you’d like to use the data shown by “capture_example.m” app. You can obtain these sensor readouts by writing a script of your own that utilizes the functions provided by the “realsense” library.

One such example is provided in the Readme file of the library: https://github.com/IntelRealSense/librealsense/blob/development/wrappers/matlab/readme.md

I suggest that you go through “capture_example.m” as it contains the logic for reading and processing sensor data apart from the code for the app UI. Your script would then look something like this:

function camera_example_without_ui()
    % Make Pipeline object to manage streaming
    pipe = realsense.pipeline();
    % Make Colorizer object to prettify depth output
    colorizer = realsense.colorizer();

    % Start streaming on an arbitrary camera with default settings
    profile = pipe.start();
    
    % Set the frame rate for image caputre
    period = 1.0;
    
    % Register a function reads and processes a frame at an interval of
    % "period" seconds
    timer( ...
             'ExecutionMode', 'fixedRate', ...    % 'fixedSpacing', ...
             'Period', period, ...
             'BusyMode', 'queue',...              % 'drop', ...
             'TimerFcn',@tmProcess ...
            );
    
    pipe.stop();
end

Please add a handle to your own timer function in place of "@tmProcess" using the logic from "tmProcess" and "set_motion_data" functions in “capture_example.m”.

I hope this helps!

Thanks & regards,

Suraj.