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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