upphafsstöð

Upphafsstöð is the Icelandic term for the origin or reference point of a coordinate system. It is the location from which all other coordinates are measured and is typically designated to have coordinates of zero in its respective frame. In two-dimensional space the upphafsstöð is often written as (0,0), and in three dimensions as (0,0,0).

Applications span mathematics, computer science, engineering, and geosciences. In mathematics and computer graphics, the upphafsstöð serves as the anchor for transformations such as translation, rotation, and scaling. In geography and surveying, local coordinate frames use an origin to define easting and northing relative to that reference point. In physics, the origin of spacetime or of a particular frame of reference is treated as the upphafsstöð for measurement of coordinates and time.

Choosing an origin affects numerical coordinates but not the intrinsic geometry; translating all points by a constant vector yields an equivalent description in a different reference frame. The selection of an upphafsstöð is therefore a matter of convenience or standard practice, depending on the problem, data availability, or interoperability with other systems. When comparing datasets or integrating systems, it may be necessary to convert coordinates to a common upphafsstöð.

See also: origin, coordinate system, reference frame, translation.