WKT (Well-Known Text)
Open BetaWKT er textaframsetningarsnið fyrir rúmfræði, notað í gagnagrunnum (PostGIS, SpatiaLite) og GIS-forritum. Einfalt og auðvelt í samþættingu.
Helstu eiginleikar
Um WKT-sniðið
WKT (Well-Known Text) is the textual encoding of geometry from the OGC standard: POINT(37.6177 55.7558), LINESTRING(...), POLYGON((...)). It is understood by every spatial database and library — PostGIS, SpatiaLite, Shapely, JTS, GEOS — and it can be read by eye, which makes the format indispensable while debugging.
The export is taken when geometry is needed as text: to paste into an SQL query, to put into a test, to pass coordinates to someone else's system, to take a quick look at what came out of the selected area at all.
The output is a single text file in UTF-8. At the top are comments with the bounding box of the area and the coordinate system, then it goes layer by layer: a line like "-- layer: roads" with one geometry per line underneath it. Coordinates are in WGS84 (EPSG:4326) with six decimal places — that is about ten centimeters on the ground.
One important thing: WKT stores shapes only. There are no names, types or other OpenStreetMap tags in the file — if you need attributes, take GeoJSON, GeoPackage or a CSV with a WKT column.
Hvaða forrit opnar WKT-skrár
Eftirfarandi forrit geta opnað, breytt og unnið með WKT (Well-Known Text) (.wkt) skrár sem fluttar eru út úr OSM2CDR:
Format specifications
- Open standard
- 3D coordinates supported
- Lossless (no quality loss)
- No attributes
- Output: 1 file
- Well-Known Text (OGC Simple Features). One geometry per line, human-readable. Direct INSERT into PostGIS / Spatialite.
Hverjir nota WKT-kort
Hvernig á að flytja út WKT
Hvernig á að opna eftir útflutning
- PostGIS — paste the lines as they are: INSERT ... VALUES (ST_GeomFromText('POLYGON((...))', 4326)); the SRID must be specified.
- Python — from shapely import wkt, then wkt.loads(line) line by line, skipping the lines that begin with two hyphens.
- QGIS — the QuickWKT plugin pastes geometry from the clipboard onto a temporary layer; for a full-fledged layer it is easier to download GeoJSON right away.
- Tables — WKT is understood by CSV import in QGIS: "Add Delimited Text Layer", with geometry from the WKT field.
- Checking — ST_IsValid in PostGIS or shapely.is_valid: self-intersections after simplification do happen, and it is better to learn about them before loading into a database.
Vinsæl kort í WKT
Fáðu kortaútflutning í WKT (Well-Known Text)
Sæktu fagleg WKT-kort úr OpenStreetMap. Tafarlaus kortagerð, hvaða svæði sem er.
Algengar spurningar
Berðu saman við önnur snið
Convert to WKT and back
Tengd snið
Oft flutt út saman
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