Geocoding is a fundamental ordering criterion of the data which are administrated by VerbaAlpina; degrees of latitude and longitude are used for geocoding. The exactness of this coding varies depending on the data type; VerbaAlpina aims at a coding as exact as possible, to within a metre. In the case of linguistic data from atlases and dictionaries, it is generally only possible to do an approximate coding according to the place name. However, in the case of e.g. archaeological data a geocoding to within a meter is actually possible. Spots, lines (as streets, rivers etc.) and surfaces can be saved. For the geocoding, the so-called WKT format (https://en.wikipedia.org/wiki/Well-known_text) is essentially used, which is transferred to a specific MySQL format in the VA database by means of the function geomfromtext() (https://dev.mysql.com/doc/refman/5.7/en/gis-wkt-functions.html and is saved like this. The output in WKT result is done by means of the MySQL function astext().
The reference grid of the geocoding is the network of municipalities in the Alpine region, which can be output as surface or as spots, as required. The basis is the courses of the municipalities’ border from circa 2014, which VerbaAlpina received from its partner "Alpine Convention". A constant update of these data (which can often change due to administrative reforms) is unnecessary because they form merely a geographical reference frame. The spot depiction of the municipality grid is deduced in an algorithmic way from the municipalities’ borders and therefore secondary. The calculated municipality spots represent the geometric midpoints of the municipality surfaces and mark only by case theirs centre. If necessary, all data can be projected individually or in an accumulated way on the calculated municipality spot. This is the case for linguistic data out of atlases and dictionaries.
Additionally, there will be a honeycombed grid which is quasi geocoded: it portrays in fact the approximate position of the municipalities to each other, but it assigns at the same time an idealised surface with each time the same form and size to each municipality territory. By doing so, two alternative methods of mapping are offered to the users. Both have their advantages and disadvantages and both offer a certain suggestive potential because of their figurativeness. The topographic depiction gives a better insight into the concrete spatiality (with its very special ground profile, single transitions, valley courses, inaccessible valley exits etc.) because of its precision. The honeycomb map in comparison allows more abstracted visualisations of the data as it balances the sizes of municipality surfaces and agglomeration resp. scattered settlements. This is especially useful for quantitative maps because perceiving the size of the surface the impression of quantitative weight is instinctively created.
(auct. Thomas Krefeld | Stephan Lücke – trad. Susanne Oberholzer)
Tags: Dokumentation Kooperation Crowdsourcing
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