Dr Mike J Smith

Plymouth University

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New JISC-OS License: devil is in the detail....

Fri, 07 Aug 2009

EDINA proudly announced a license renewal of OS data for the digimap collection which included a variation to the original agreement and some new clauses. Of most interest to academics are the changes to maximum allowances for internet publication, something Ive banged on about at the Journal of Maps for some time (maximum ~A5 map was essentially allowable for any academic journal publication). Thankfully they have now ditched the ludicrous maximum physical size/ground area rules (meaning you can now legally produce a map of the whole of the UK. Miracle!) and replaced it with, to be frank, an equally ludicrous "number of pixels" measure. All data now must be rasterized; no vector linework is allowed whatsoever regardless of the impact upon quality. The limitation is the maximum number of pixels at 1,048,576. Yes that's 1 megapixel.

Let's run through an example. Most people are familiar with pixels per (linear) inch (analagous to dpi for raster imagery) which means at 100ppi it takes 10,000 pixels to represent 1 square inch. A5 (148x210mm) weighs in at ~48 square inches, meaning you need ~480,000 pixels. However 300ppi is common for printing (and PDF viewing), but remember this is area, so that's nine times the size of a 100ppi file. Yup, an A5 image at 300ppi is ~4,320,000 pixels, four times over the OS limit.

Either I've made a horribly (and blindingly) obvious mistake (and do correct me if I'm wrong and I'll eat humble pie) or they must have been smoking something strong when they came up with this. This is actually worse than the previous agreement and by my reckoning means that the biggest figure you can have at 300ppi is 8.4x8.4cm. Now that really is great value for money.... and I thought things really couldn't get any worse.

P.S. Not quite sure why the figure is set at 1,048,576, but that's 1024x1024, which is of course 1kbx1kb.

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