GDAL Virtual Raster (beta)
Open BetabetaVRT 是 GDAL 对栅格数据集的 XML 描述。我们将 VRT 与渲染后的 GeoTIFF 一并打包为单个 ZIP（map.vrt.zip）——否则 gdalinfo/gdal_translate 会因「map.tif not found」而报错。测试版：目前为不含概视图的单一波段组。
主要特点
关于 VRT 格式
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.
打开 VRT 文件的程序
以下程序可以打开、编辑和处理从 OSM2CDR 导出的 GDAL Virtual Raster (beta)（.vrt.zip）文件：
格式规格
- 开放标准
- 仅 2D
- 无损（无质量损失）
- 无属性
- 输出：1 个文件
- GDAL Virtual Raster (.vrt). XML descriptor referencing source rasters; lazy mosaicing without copying pixels.
谁在使用 VRT 地图
如何导出 VRT
导出后如何打开
- 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.