Mapinfo Virtual Raster is a virtual template of a raster that can be loaded, displayed, and operated upon in MapInfo Pro just like any other regular raster format. The raster data is acquired or generated on-demand, at run time. The MapInfo Virtual Raster (MVR) is a simple XML file - using the “.MVR” file extension or you can use a “.XML” extension if you prefer. MVR could be rendered into MapInfo Pro via the raster handler interface.
MVR is structured just like a normal raster which means it needs to have fields and bands defined, cell size and raster origin defined and all the other properties of a raster clearly defined. In the XML, this is done by creating a RasterInfo element.
However, most of the raster properties can be derived from the raster sources that are referred to by the virtual raster. Consequently, the user usually has to do little other than link raster sources to fields and bands.
MVR data is cached by the raster engine just like any other raster data. If the requested data is not in the cache, then the virtual raster engine will be invoked to provide the data. This will trigger a process that may be deep and complex, depending on how that virtual raster data is defined.
Ultimately, data will be acquired from some source raster. The MVR will require this data to be interpolated into its own geometry which can change depending on what resolution level of the MVR you are requesting data for. This will trigger a requirement to acquire source data at some resolution level which may be anywhere from underview levels through to overview levels. For this reason, source rasters should be in MRR format or have overview cache files.