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I'm trying to make a custom CRS in QGIS, to get a projection similar to this map, where Toronto is at the center of the map :

enter image description here

The picture above was created with an online tool : worldmapcreator

But I can't get enough details with this tool, that's why I need a way to project a similar map in QGIS.

I tried to create a custom CRS, but I'm not a geographer... I'm not familiar with proj4 language and I struggle a lot. I only managed to change the central longitude on a WGS 84 projection, but I can't move the equator. The only time I was able to put Toronto at the center was in a circular map, but I need an rectangular map...

So, what parameters should I use to get a projection featuring :

  • the whole world in a equirectangular map
  • Toronto at the very center of the map

I don't care about the distortions at the top and bottom of the map.

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A helpful page for customizing projections in QGIS is this one, explaining the parameters of Proj.4 projections.

To get you started I would sugget the Michigan oblique Mercator projection; it should get you pretty close to what your after, which makes it a good starting place parameter-wise.

+proj=omerc +lat_0=45.30916666666666 +lonc=-86 +alpha=337.25556 +k=0.9996 +x_0=2546731.496 +y_0=-4354009.816 +no_uoff +gamma=337.25556 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs

Another option is the Miller projection [+proj=mill] or the Equidistant Cylindrical (Plate Carrée) [+proj=eqc] if you're wanting to keep the rectangular shape. (I have not experimented with rotating the perspective - lambda, phi, gamma - on these projections though)

Hope this helps get you started.

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    Oblique Mercator seems to be the only rectangular projection that allows rotation, thank you for the formula. I managed to put Toronto at the center. The only downside is that mercator projection crops a little part of the map, so I can't get 100% of the surface of the world. I tryed Miller and Plate Carrée, but rotation didn't work. So, I guess this is as close as I can get, using QGIS. – Ghajini Apr 29 '18 at 15:39
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Upon some further research, I came across "Adaptive Composite Map Projections" by Bernard Jenny. In it I found this graphic of interest. Maybe the Hammer or Modified Hammer projection is the way to go.

I also came across Flex Projector, a custom projection software Jenny has developed. I haven't downloaded it myself, but it might be worth a shot; looks like it could be exactly what you're after.

B.Jenny

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    Very interesting! I will give it a try, thank you. – Ghajini May 3 '18 at 11:21

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