Can't find units of measurement for the sample_annotations.json

[odd2022]

Hello,

Sorry, it might be written somewhere but I can't find what are the units of measurement for the annotations in sample_annotation.json. For example is 'size' in meters ? What about 'translation' ?

I would also like to know to what corresponds each coordinate of 'translation' and 'rotation' please and in which frame the coordinates are (ego frame ? camera frame ?) because it is said that it is the global coordinate system but i don't understand to what it corresponds.

Finally, considering the image you gave: https://www.nuscenes.org/static/media/data.9ef46c59.png

When the ego position is tracked, does it corresponds to the IMU position ?

Let me know if I am not clear in my questions,

Have a nice evening,

[whyekit-motional]

@odd2022 hope these help you:

• The units and coordinate frames can be found in the schema: https://github.com/nutonomy/nuscenes-devkit/blob/master/docs/schema_nuscenes.md

• The ego frame refers to the center of the rear axle projected onto the ground, and yes, the IMU is located roughly at the center of the rear axle.

[odd2022]

• he center of the rear axle projected onto the ground, and yes, the IMU is loca

Thank you so much for your answer, I found almost everything I wanted. Do you know if there is anywhere I can find more informations thant about the ego such as the speed of the vehicle or the steering wheel angle ?

Have a nice day and thank you again for the answer

[whyekit-motional]

@odd2022 for information about the ego speed and the steering wheel angle, do check out the CAN bus expansion, and the accompanying tutorial: https://colab.research.google.com/github/nutonomy/nuscenes-devkit/blob/master/python-sdk/tutorials/can_bus_tutorial.ipynb

[odd2022]

Okay, thank you !