GeoTorrent—peer to peer geospatial data

ER Mapper is using file sharing à la Napster used to distribute terabytes of geospatial information. BitTorrent peer-to-peer technology makes multi-cast serving of gigabyte datasets possible.

ER Mapper has applied peer to peer technology, as used by Napster and others to share music on the internet, to the distribution of massive geo data sets. The technology, ‘GeoTorrent,’ is used to share large imagery datasets which can easily be many gigabytes in size. uses bittorrent technology to alleviate the traditional bottlenecks and costs of internet data distribution.


ER Mapper’s Richard Orchard said, ‘At ER Mapper, we deal with multi gigabyte geospatial images. A good quality air photo of a state is going to be a large file! Previously, you could download data, but in such small chunks that they are unusable. People don’t want a square kilometer, they want a whole region, state or country. Because of the amount of data involved, the traditional means of delivery were too expensive. GeoTorrent, which uses BitTorrent’s brilliant and perfectly legitimate technology, allows people to download the datasets they want quickly. It also allows them to share their own datasets.’

500 TB

An indication of the bandwidth needed for traditional file distribution can be got from the following math. 1000 downloads of 100 5GB files would amount to 500 terabytes of bandwidth! The cost of serving this amount of data would be astronomical. Download speeds would likely be dire, taking weeks or more to download a single file.


The answer is BitTorrent technology. Users who have downloaded data offer their untapped upload bandwidth to send data to other peers. Each new participant adds to available bandwidth at no cost to the system. A website, started out as Orchard’s research project. provides access to several terabytes of geospatial information, including continental and worldwide Landsat mosaics and complete vector datasets for the United States. New datasets are continually being added.

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