The |hauteur filter is applied to an image element (LOGO tag, typographical image, ...) and returns the calculated height for that element once it has been filtered.
The height returned is expressed in pixels.
Example: after having applied the |image_reduire{250, 500} filter to a logo, we can find out the actual height of the final image by writing [(#LOGO_DOCUMENT||image_reduire{250,500}|hauteur)].
See also the |largeur filter.