[Qgis-user] How to reproject maps of world grasslands

[Martin]

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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