Orientation (map)
The orientation of maps or plans is done by grouping them according to the north (default, default) or to another reference direction indicated by the north arrow . Orientation is necessary in order to be able to compare the plan or map contents with nature.
The term "orientation" or "orientate oneself" comes from the historical representation in which maps were often aligned with Jerusalem = up. Jerusalem was equated with the Orient . Orienting a map meant turning the map so that the Orient is on top.
Maps, thematic maps
Before using a map , it is held horizontally and rotated until its right or left edge points north. This can be done in several ways:
- By comparing the distance covered with the one on the map
- by approximating alignment with the sun
- by aiming at prominent map points (mountains, churches, etc.) and rotating the map at the same time until both directions coincide.
plans
When it comes to the floor plan of technical plans, it is usually quickest to align the building edges or boundary lines. It becomes particularly precise through alignment , ie through the creation of parallelism between a line and its plan representation.
If, on the other hand, the plan shows an elevation or a side view, it is held vertically and compared directly with the building or the level shown.
Achievable accuracy
How accurate the alignment of a map is depends on the method, the weather and the time required:
- in ~ 1 minute to 10–20 °: after the next environment, e.g. B. the direction of the distance covered immediately before
- in ~ 2 minutes to ± 10 °: according to the position of the sun with the "clock method": hour hand to the sun, south ≈ middle between 12 h and pointer (attention with summer time )
- Accurate to 1 ° in 3–5 minutes: Sighting one or two distant targets (mountain peaks, villages, crossroads, etc.).
If further points are to be entered in the map, the third method can be refined to around 0.1 ° using simple measuring methods - see measuring table (map sheet mounted on a horizontal plate) or geodetic solar azimuth .
Individual evidence
- ↑ Günter Petrahn: Fundamentals of Surveying , Cornelsen, 5th edition, 2003, ISBN 978-3464433355
- ^ Erwin Reidinger : Medieval church planning in town and country from the point of view of structural archeology; Position, orientation and axis bend. In: Contributions to Medieval Archeology in Austria , Volume 21/2005, Vienna 2005, pp. 49–66, ISSN 1011-0062
- ↑ Erwin Reidinger: Passau, St. Stephan Cathedral 982: Achsknick = time mark . In: The Passau Cathedral of the Middle Ages , publications by the Institute for Cultural Area Research in East Bavaria and the neighboring regions of the University of Passau, Volume 60, Passau 2009, pp. 7–32, ISBN 978-3-932949-91-3 , ISSN 0479-6748