Questions about the imu data

[JadeGreened]

I finally get the imu data from my hololens! Thanks a lot~. But I notice that the imu data is a 4x4 matrix like this

[[ 0.05868477 -0.9801954 0.18913764 0. ]
[-0.96467817 -0.00694191 0.26333955 0. ]
[-0.25681123 -0.19791096 -0.94598055 0. ]
[-0.12868184 0.15060404 -0.22494759 1. ]]

Since I am new to imu-activity-recognition, I have no idea of what the rows and the columns mean. And the microsoft documentation did not explain the shape of the matrix. Could you please provide me with more detailed explanation or show me the relavant documentation, plz~.
if the data is present like this:
Research Mode IMU
Accelerometer (m/s^2)
Gyroscope (deg/s)
Magnetometer
Then why the matrix is four-dimensional？

[anjelomerte]

How exactly are you getting this matrix, could you share your implementation? Looking at https://github.com/jdibenes/hl2ss/blob/main/viewer/client_stream_rm_imu.py, 6 values (sensor_ticks, soc_ticks, x, y, z and temperature) are returned.

[JadeGreened]

while (enable):
    data = client.get_next_packet()

    print(f'Pose at time {data.timestamp}')
    print(data.pose)

    imu_data = hl2ss.unpack_rm_imu(data.payload)
    count = imu_data.get_count()
    sample = imu_data.get_frame(0)

    print(f'Got {count} samples at time {data.timestamp}')
    print(f'First sample: sensor_ticks={sample.vinyl_hup_ticks} soc_ticks={sample.soc_ticks} x={sample.x} y={sample.y} z={sample.z} temperature={sample.temperature}')

client.close()
listener.join()

Actually It is the script that you showed to me. "data.pose" is the 4x4 matrix.

How exactly are you getting this matrix, could you share your implementation? Looking at https://github.com/jdibenes/hl2ss/blob/main/viewer/client_stream_rm_imu.py, 6 values (sensor_ticks, soc_ticks, x, y, z and temperature) are returned.

[JadeGreened]

sry~ I forget the comment on the top of the script

[JadeGreened]

problem solve :)

[JadeGreened]

But if I want to have three types of data together

Port

Options:

hl2ss.StreamPort.RM_IMU_ACCELEROMETER

hl2ss.StreamPort.RM_IMU_GYROSCOPE

hl2ss.StreamPort.RM_IMU_MAGNETOMETER

Should I open 3 client for each ports?

[jdibenes]

Hello,
Yes. The data volume for these channels is low so multithreading should work or you can use the multiprocessing utilities like in the samples.