Changeset: 71376590
calibration_point
Closed by Lokalfuerst
Tags
created_by | Vespucci 13.0.4.0 |
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locale | de_DE |
source | survey and mapbox satellite |
Discussion
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Comment from archie
Hallo, was ist der Sinn dieser Änderung und des Tags?
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Comment from archie
Wie kann man die calibration_points benutzen? Bin neugierig auf deine Antwort.
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Comment from Lokalfuerst
Hallo archie,
manchmal sind Overlay-Karten wie Mapbox Satellite oder Bing versetzt im Vergleich zur OSM-Karte. Das war früher nicht selten in Wohngebieten an Häusern zu erkennen. Von einem Mapper gezeichnete Häuser waren deckungsgleich, während andere mit gleichem Offset in eine Richtung versetzt waren.
Für den Mapper stellt sich die Frage, welche Einträge die korrekt positionierten sind. Man kann für diesen Zweck nicht jedesmal eine GPS-Aufzeichnung vor Ort vornehmen.
Daher habe ich hier einen eindeutig identifizierbaren, fixen Punkt gekennzeichnet, um einen Referenzpunkt in der OSM-Karte zu haben.
Gibt es eine andere Lösung?
Viele Grüße
Lokalfuerst -
Comment from archie
Das habe ich mir schon gedacht. Dachte aber, dass es etwas hoch-präzises wäre, so wie gps-rtk oder so. Also nur ein Referenzpunkt. Gut danke schön! Uebrigens, die overlay-Karten sind noch immer häufig versetzt. Heidenarbeit das alles richtig auszurichten bevor man anfängt neue Gebiete zu zeichnen. Mach's gut!
/archie
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Comment from Seandebasti
Hi, I am just curious about calibration tags. So I understood right: your calibration_point is only for imagery quality for openstreetmap but not for precise calibration. maybe there should be a usage tag like e.g. calibration:usage=openstreetmap imagery or something??
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Comment from Lokalfuerst
Seandebasti,
If I go out with a GPS unit and draw a line around a building, then I have the exact position of the building. This could be a reference point.
However when mapping one does not always measure physically, but one recognizes the objects in the field and than takes overlay imagery like Esry, Mapbox, Bing etc. as help to draw the map. Now in some areas, if I draw according to these three, the objects would be at different locations due to imaging error. The question now is, what is the correct location. Then I can take the discussed, possibly self-aquired, reference point, compare it with the overlay images and move the images to match in order to prevent drawing objects at wrong positions.
In earlier times in some countries there was a considerable offset between reality and available imagery so that objects, villages, highways etc are all drawn at wrong position. The best way to get this straight is individually by hand. However one needs so be a bit sensitive, it does not look good, if 100 objects are misplaced and the corrected 1 mismatches the rest of the 99..Best regards
Lokalfuerst -
Comment from Seandebasti
thanks, interesting facts. I guess armchair mappers should be more sensitive regarding your thoughts. (including me), I guess, a lot of people are not aware of this.
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Comment from Lokalfuerst
actually just before i commented to somebody about some mistagging from my part that some situations are much more complex than they seem at first glance. This however makes the mapping so exciting. Modern mapping is about setting up structures about existing visible and invisible objects. By 'connecting the dots' you form structures and discover relations otherwise remaining unrecognized.
Frohes mappen!
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