[R-sig-Geo] Antw: Re: import a jpg/etc. map into R?

[Alexander Arpaci]

When I used to do something like this I used the georeferencing
funtionalities of ArcGis
You could try to fix the old spanish map with lat and long over a actual
map referencing to cities, rivers or ...

just a thought
hth
alex


MSc. Alexander Arpaci
Assistant researcher

Department of Forest - and Soil Sciences
Institute of Silviculture
Tel. +43-1-47654-4081
e-mail: alexander.arpaci at boku.ac.at
www.wabo.boku.ac.at 
>>> Marcelino de la Cruz  13.09.11 12.47 Uhr >>>
Hi Malcolm,

digitize package may be  a first try

http://finzi.psych.upenn.edu/R/library/digitize/html/00Index.html

HTH,

Marcelino


At 12:33 13/09/2011, Malcolm Fairbrother wrote:
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>Dear all,
>
>The answer may well be 'no', but does anyone 
>know of a straightforward way to import into R a 
>map in the form of a simple jpeg (or bmp, gif, etc.) image file?
>
>I'm thinking of a situation where you have something like this:
>
>http://www.learnnc.org/lp/media/uploads/2007/09/1492spain.jpg
>
>or
>
>http://www.spainthenandnow.com/userimages/Spain%20General%20Map%20Wikimedia.png
>
>Latitude and longitude lines are given in the 
>image, and they should be usable for identifying 
>the geographical location of any given pixel, 
>but the projection of the map is not immediately 
>apparent, and the map is not in a vector format 
>where lines or polygons can be easily 
>identified. What I'd like to do is read in this 
>kind of file, have R find the edges (identified 
>somehow by differences in pixel colours I 
>guess), and convert the areas defined by those 
>edges into a SpatialPolygons object, with lat/long coordinates.
>
>There may well be no easy way to do this (or not 
>even a difficult way), but I thought I'd check 
>if anyone has any ideas. I prefer to use R, but 
>if some other (preferably open source) software 
>could help me, I'd be interested to know. Even 
>suggestions like "IF you could get it into X 
>format, THEN you could*" might be useful. I'm 
>not a GIS person, unfortunately. On the other 
>hand, I am pretty handy with R, and a regular 
>user of several of the maps/spatial/raster packages.
>
>Any help would be much appreciated.
>
>- Malcolm
>
>
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____________________________________

Marcelino de la Cruz Rot
Depto. Biologia Vegetal
EUIT Agricola
Universidad Politecnica de Madrid

tel: 34 + 913365435
____________________________________  
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