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ArcGIS Desktop has a the Raster Mosaic Dataset, QGIS and friends have Virtual Raster Tables.

A skim of the documentation reveals much similarity. They both create or enable an alternate representation of data that sits somewhere else without having to actually create a new image. Examples include creating a single seamless image from many tiles without actually creating that single image, or mix-and-matching channels or selectively removing value ranges from the result, and more.

How far does that similarity extend? Does an RMD enable things that VRT can't? What are they? What can one do with VRTs that you can't with RMDs?

In short, assuming one has equal access to and comfort using both tool chains, when should a person use Raster Mosaic Datasets and when are Virtual Raster Tables the order of the day?

PolyGeo
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matt wilkie
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  • wow. 12 days and not a single response, though a couple of up-votes and a favourite. Too general a question, or perhaps there's no one about with enough experience in both to comment? – matt wilkie Mar 19 '14 at 23:30

1 Answers1

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VRT can be used cross platform (if you are using relative paths and you place in the same directory as the images, otherwise the path names are not the same) and read it with ArcGIS. It is also easy to read what you have in it.

It is great for processing large collections of coherent non overlapping images (lazy computation at its best)

RMD has a set of mosaicking rules that are used to dynamically mosaic the rasters (seamlines, rules for overlapping pixels, color matching rules). You can also use non rectangular boundaries for visualisation (which is not possible with vrt).

It is far more flexible and great to use for visualization.

radouxju
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    The mosaic image dataset allows for rasters embedded in the database (managed) creating one very large file system object whereas VRT are file based and can be many files in multiple directories: very easy to break! Careless folder moving and renaming causes issues; conversely VRT is just XML so it is also easy to fix using a text editor find & replace. – Michael Stimson Mar 27 '14 at 21:50