what is the length unit of focal length?

[GLY-123]

No description provided.

[hbardak]

In the real world millimeter (mm ) but you need to know the aperture size to get an angle of view.

In the ML dev world is in pixels apparently :)

[GLY-123]

In the real world millimeter (mm ) but you need to know the aperture size to get an angle of view.

In the ML dev world is in pixels apparently :)

For example,what does the prediction["focallength_px"]=1402.6646 mean? does it mean focal_lentgh=1402.6646(mm)? or othrewise.

[hbardak]

def fpx_from_f35(width: float, height: float, f_mm: float = 50) -> float:
Convert a focal length given in mm (35mm film equivalent) to pixels.
return f_mm * np.sqrt(width**2.0 + height**2.0) / np.sqrt(36**2 + 24**2)

[NicolaCovallero]

As said, the focal length is given in pixel units. The physical quantity, measured in meter scale, is dependent on the physical size of the pixel, that in many applications is unknown but often unnecessary. if you known which sensor is used to capture your image you can convert the focal length to meter scale given the pixel size.