Hi,

In JAD3D we can import slope distances, but without their corresponding azimuth angle. Azimuth angles are imported separately and as far as I understand are not linked to specific slope distances.

Yes, observations a treated as independent observations. Moreover, instruments exist, which only provide specific observations, e.g. distance measurements (Mekometer) or angles (theodolite). In general, a polar triple does not exist, thus, observations are taken into account according to their type and not according to the instrument.

So how are slope distance measurements used to get dh and horizontal distance data? I mean without the azimuth angle we cannot use them to get horizontal and vertical distances. Am I missing something?

An azimuth is generally not required to determine the horizontal distance or the difference in height, only the zenith angle. Anyway, JAG3D is an adjustment software that processes terrestrial observations - not only from total stations - and derives Cartesian coordinates. However, JAG3D is not software that converts polar elements into Cartesian coordinates. If you want to calculate the horizontal distance and height difference from the slope distance and zenith angle, simply use Excel or a similar tool, because an adjustment is not required in this trivial case.

Kind regards
Micha