dcm_to_quat may have wrong sign on the img part

[gzhang8]

I recently find dcm_to_quat is not consistent with the one https://github.com/FugroRoames/Rotations.jl

The later gives me the correct result, but I haven't closely inspected code in both. Maybe it is still useful to pass the information here.

[ronisbr]

Hi @gzhang8

Thanks for the report. However, keep in mind that Rotations.jl always perform active rotations:

This package assumes active (right handed) rotations where applicable.

This means that it rotates vectors in coordinate systems. ReferenceFrameRotations.jl, on the other hand, always perform passive rotations, i.e. it rotates the reference systems. This is why the result is inverted.

[gzhang8]

I see. Thanks for the information. New knowledge learned 👍