Thank you very much. I tried this suggestion and it works perfectly!
Forgive my ignorance, but how did you know that '+proj=igh' would
produce the correct result? I understand that igh means Interrupted
Goode Homolosine, but where did you find this information (this is for
my education)?
I am going to write to WWF and suggest that they make the grasslands
shape file available in WGS84 (i.e. EPSG 4326), as I would like to
direct others to it without the need for providing an explanation of how
to transform the data.
I discovered that ArcGIS understands the Interrupted Goode Homolosine
CRS. A friend with ArcGIS has now converted it to EPSG 4326 for me and
this also works fine and produces the same result as your excellent
suggestion.
Ciao, Martin
On 20/03/17 07:54, Paulo van Breugel wrote:
Using the definition on the proj4 page, you can define a custom CRS
(settings --> custom crs). Just fill in under parameters '+proj=igh'.
I just tried and it gives a good match
Note that this grassland layer is based on the terrestrial ecoregional
map of WWF [1]. If you over overlay that on your grassland layer,
using for the latter the Interrupted Goode Homolosine CRS, you see
they will overlap perfectly. You could in fact easily recreate the map
using the ecoregional map.
Cheers,
Paulo
[1]https://www.worldwildlife.org/publications/terrestrial-ecoregions-of-the-world
On 20-03-17 07:46, Martin wrote:
Many thanks Raymond: that is helpful. Now at least I know what the
projection is! As QGIS has so many projections it never occurred to
me that there may be one that it didn't include. I will now see if
there is some other way - outside QGIS perhaps? - to convert this
projection into something more friendly (so to speak).
Martin
On 19/03/17 21:30, Raymond Nijssen wrote:
Hi Martin,
Sorry, I cannot really help you.
Your data seems to be in the (quite odd for distributing data)
projection:
https://en.wikipedia.org/wiki/Goode_homolosine_projection
And it is not recognized by qgis.
Proj4 seems to know it though:
http://proj4.org/projections/igh.html
And I found this:
http://gis.stackexchange.com/questions/17263/is-it-possible-to-use-the-goode-homolosine-projection-in-qgis
Hope it helps (a bit),
Raymond
On 19-03-17 20:49, Martin wrote:
Hello folks!
I would like to plot a simple map of the WWF World Grassland Types
(the
shape file is available at
https://www.worldwildlife.org/publications/world-grassland-types
It is in an unusual projection. The .prj file is:
PROJCS["World_Goode_Homolosine_Land",GEOGCS["GCS_WGS_1984",DATUM
["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM
"Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION
["Goode_Homolosine"],PARAMETER["False_Easting",0.0],PARAMETER
["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER
["Option",1.0],UNIT["Meter",1.0]]
The map does not include the outline countries of the world and
therefore I would like to add these (perhaps the NaturalEarth 110
million scale country shape file, which is in WGS84).
However, I cannot figure out how to align the grassland layer and the
110 million NaturalEarth layer. As I understand it, I should use
Save As
to reproject the grassland shape file with a new CRS (perhaps
Mercator).
With Enable on the fly CRS transformation enabled I should then be
able
to put the two shape files together - but I am darned if I can obtain
anything sensible: I cannot get the two layers to align in any way.
With grateful thanks for any help, Martin
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