GDAL Virtual Raster (beta)
Open BetabetaVRT on GDALi XML-kirjeldus rasterandmestiku jaoks. Me pakime VRT-i koos renderdatud GeoTIFF-iga ühte ZIP-i (map.vrt.zip) — vastasel juhul ebaõnnestuvad gdalinfo/gdal_translate veaga "map.tif not found". Beeta: praegu üks ribakomplekt ilma ülevaadeteta.
Põhiomadused
Vormingu VRT kohta
VRT is a service format of GDAL: an XML file that contains no pixels but describes where they lie and how to read them. That is the usual way to stitch mosaics and redefine referencing without copying gigabytes of raster.
We hand over the VRT together with the raster itself: the map.vrt.zip archive holds the XML description and the rendered map as a GeoTIFF. That was done deliberately — a lone .vrt would refer to a file you do not have, and gdalinfo simply would not open it.
The XML records the WGS84 coordinate system, the georeferencing (corner coordinates and pixel size) and three RGB bands, each pointing at the corresponding band of the GeoTIFF. The format is in beta status: it is one set of bands with no overview pyramids, and the raster itself is a flattened picture of the map rather than vector layers.
Milline programm avab VRT-faile
Järgmised programmid ja rakendused suudavad avada, redigeerida ning töödelda OSM2CDR-ist eksporditud GDAL Virtual Raster (beta) (.vrt.zip) faile:
Format specifications
- Open standard
- 2D only
- Lossless (no quality loss)
- No attributes
- Output: 1 file
- GDAL Virtual Raster (.vrt). XML descriptor referencing source rasters; lazy mosaicing without copying pixels.
Kes kasutab VRT-kaarte
Kuidas eksportida vormingusse VRT
Kuidas pärast eksporti avada
- Unpacking is a mandatory first step: map.vrt and map.tif must lie next to each other in the same folder, since the reference inside the XML is relative.
- GDAL — gdalinfo map.vrt will show the size, the referencing and the bands; gdal_translate will convert the set into GeoTIFF, PNG or COG.
- QGIS — Layer → Add Raster Layer and pick map.vrt; the layer will land in its place by coordinates.
- A mosaic — your own .vrt over several rasters is assembled with gdalbuildvrt out.vrt tile1.tif tile2.tif, if the map has to be stitched with other data.
- Editing by hand — VRT is plain XML: the path to the raster, the referencing and the band descriptions can be fixed in a text editor.
Populaarsed kaardid vormingus VRT
Hangi kaardiekspordid vormingus GDAL Virtual Raster (beta)
Laadi alla professionaalsed VRT-kaardid OpenStreetMapi andmetest. Kohene genereerimine, mis tahes ala.