Hi Folks,

James is correct, there are two ways to import existing Ground Control Points. The first is in CSV format for imported maps which has to be run by a server admin - ideally this should be exposed as part of the user interface. This can handle multiple maps and multiple points at once.

The second is doing it by hand via the user interface - a user can paste in coordinates manually, so that would be the easiest and quickest way for individual maps. In the control panel, click "control points" link and then the "add control point manually" button, and paste in the coordinates.

Regarding projections - for many old maps these cannot be used accurately, because paper stretches, the lens on the camera may distort things, the map may have folds or be made of several images, or it may be inaccurately surveyed. In theory it could be possible to reverse engineer the original projection based on the solution of the control points - that could be a fun exercise for someone to do even though it would have no utility for the warper.

Regards,

Tim

On 27 April 2015 at 12:48, Rob H Warren <warren@muninn-project.org> wrote:

Mapwarper could do so without too much trouble (Tim?); it is unlikely that the projection can be estimated since an algorithm could not differentiate between error and projection fit. -rhw

> On Apr 25, 2015, at 9:18 AM, James Heald <j.heald@ucl.ac.uk> wrote:
>
> There is a slot for that in the Commons {{map}} description template
> http://commons.wikimedia.org/wiki/Template:Map
>
> using the field "projection",
>
> with a handful of values that have internationalisations defined at
>
> http://commons.wikimedia.org/wiki/Template:I18n/map_projection
>
> But it's not clear whether/how the template should store relevant parameters.
>
> I'm not sure whether the information can be used as a baseline by MapWarper yet. (Tim ?). Or whether there are good scripts available to estimate a projection, given georeferencing points.
>
> -- J.
>
> On 25/04/2015 13:06, Rob H Warren wrote:
>> If we are going to go through the trouble of storing geo-referencing data, we would be silly not to add original projection type when known. There are a few specs on github for ideas. -rhw
>>
>>> On Apr 24, 2015, at 8:28 PM, James Heald <j.heald@ucl.ac.uk> wrote:
>>>
>>> MG_1773.jpg,12,23,11.2,32.2
>>> IMG_1773.jpg,12,23,10.2,31.1
>>>
>>> from which there is script that an admin can use to add the data to the map-warper.
>>>
>>> This doesn't capture all of the data stored by Klokan Georeferencer -- eg the useful information as to what layer the image was georeferenced against -- but is enough to get the geo-referencing data into the system, and to then get it out in various formats, including serving georeferenced tiles.
>>>
>>>
>>> Sorry if it's all still a little bit round-the-houses; but with luck everything should get a bit more streamlined, as we get more geared up for large scale import.
>>>
>>> (There are already a couple of thousand images on Commons with links to external georeferencing, either at NYPL or the British Library; plus ready to be uploaded to Commons a further 6,000 georeferenced map images from the BL Mechanical Curator collection, just as soon as I've got auto-categorisation a bit more worked out, with that number currently increasing by approximately a further 100 georeferenced images a day
>>> https://commons.wikimedia.org/wiki/Commons:British_Library/Mechanical_Curator_collection/georeferencing_done ).
>>>
>>> As far as I know, nobody has yet actually used the script to import pre-existing georeferencing onto the warper.wmflabs.org server, so I'm quite interested to see how you get on!
>>>
>>> Best regards,
>>>
>>> James.
>>
>>
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