Request for Information – FOI14495
Thank you for your email of 12 September 2014 which we acknowledge, requesting information from Ordnance Survey in accordance with the Freedom of Information Act (FOIA) 2000.
The request is as follows:
Can you please let me know what the little cross is on the map under the ‘oo’ in Wood?
I can confirm that Ordnance Survey does not hold any information explaining what the little cross on the map is.
However, under our duty to provide advice and assistance as stipulated in Section 16 of the FOIA, we can provide the following explanation which may assist you in this matter.
Ordnance Survey cartographers believe that the item in question is a small piece of dirt. They believe it is a small piece of dirt because there is no corresponding marking on the large scale. Also having worked for years on conventional mapping using plastic overlays which undergo reprographic processes they were aware of the problems with dirt.
Additionally when the overlays were scanned in and converted to digital format the cartographers were aware that pieces of dirt on the overlays were also scanned and showed as tiny marks on the mapping.
When they produced the first editions digitally the cartographers looked at the electronic data and removed the largest pieces of dirt from the data, however there are still many small pieces remaining like the one you have noticed.
When working on conventional plastic overlays the cartographers taped clear film over the plastic to try and prevent dust and dirt settling. They also used large cloth dust covers to lie over the desk at night. Unfortunately if a small piece of dirt or dust got on the plastic positive overlay when it was converted to a negative that dirt would then be etched on to the negative.
The cartographers did check negatives and added a chemical to them to prevent the largest pieces of dirt getting through to the product, and in the days of only paper mapping it was not so critical because the smaller bits did not show up at printing stage (unlike digital data where you can blow detail up and see all the imperfections in the raster detail that was scanned in).
Incidentally that piece of dirt is not on our current mapping; it was removed sometime between the 2010 and 2013 editions.
Ordnance Survey is grateful to you for identifying the discrepancy and apologises for any inconvenience caused. I hope the above information is of use to you.
Your enquiry has been processed according to the Freedom of Information Act (FOIA) 2000. If you are unhappy with our response, you may request an internal review with our FOI Internal Review Officer, by contacting them as follows:
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