What does magnetic_field mean?

[peci1]

What does tag world/magnetic_field mean?

Normally, the magnetic field vector changes with both position and time. What would this single vector represent? Is it something like rough approximation of the field strength at 0,0,0 pose?

I'd suggest either removing this field, or renaming it, because its meaning is quite unclear.

[peci1]

Also, the fact that the field is required and has a default value is quite impractical.

I can imagine, if the field were optional, that setting it could mean that a static value is being forced. However, with its current definition, this use-case is impossible.

The current magnetometer sensor in gz-sim is a bit dichotomic. It requires and reads this tag, but then it throws the values away, using the baked-in table of values.

[peci1]

I found this 9-year-old discussion in Gazebo Classic, from which it seems that the magnetic_field tag really forces the assumption that the field is constant everywhere. That's really unfortunate given the tag is required with a default.