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1

I need to ask you guys after reading this article.

Any speculations on why some maps showed it?

What can be the cause of inaccuracies in (web)Maps?

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Not sure how this is relevant to GIS? Geography perhaps? – Stev_k Nov 22 '12 at 15:06
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It is likely to be a cay - en.wikipedia.org/wiki/Cay – Mapperz♦ Nov 22 '12 at 15:16
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@Stev_k I believe the point of the question (and why it may be GIS related) is why do the maps show it exists when it doesn't. It's a good example of how real world features change but maps don't reflect it (assuming it ever existed in the first place!). – GIS-Jonathan Nov 22 '12 at 17:55
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Maybe we should Edit this question to "What can be cause of inaccuracies in (web)Maps?" to prevent it from being closed as too localized? – Devdatta Tengshe Nov 23 '12 at 8:21
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@user1702401 That is because Google does different image processing on areas marked as land. – Devdatta Tengshe Nov 23 '12 at 8:22
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2 Answers

up vote 2 down vote accepted

It is on this Chart:

"the island was discovered on an 1876 voyage by a vessel called Velocity"

“Caution is necessary while navigating among the low lying islands of the Pacific Ocean. The general details have been collated from the voyages of various navigators extending over a long series of years. The relative position of many dangers may therefore not be exactly given”.

http://farm9.staticflickr.com/8482/8209721222_740033147e_o.jpg

source: http://www.theregister.co.uk/2012/11/25/sandy_island_seen_in_1908_chart/

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up vote 8 down vote

There are 3 possible reasons what could have happened:

  1. There was actually an island at that location, and is not longer present. The possibility of this is remote.
  2. This could have been a Copyright Easter egg. This is mis-information that is put in a map, so that when someone copies it, you can use it as a red flag to indicate that copying took place. See this page for more examples. http://wiki.openstreetmap.org/wiki/Copyright_Easter_Eggs
  3. It was an error. This could have been due to various reasons, as sinister as an unscrupulous survey company, who didn't actually survey the area, to something as simple, as it was copied from an old map that had a printing error.

This situation is an illustrative example of just how important metadata is, and how it should be maintained and saved when merging data from various sources.

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+1 All good possibilities. My money is on option 3 though because Copyright Easter Eggs tend to be a bit more subtle, like a extra tiny cul-de-sac in a crowded city center or the name of an obscure small hill. That said, at this scale, perhaps Sandy Island is subtle. As well as for Copyrighting purposes some cartographers are known to put a "signature" into their work, not for the benefit of an employer but for their own vanity, which is another possibility. And could be classed as option 2.5 here :) – MappaGnosis Nov 23 '12 at 9:24

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