# How to display a map using a new projection (new latitude/longitude to XY conversion formula)

I have constructed a new formula for planar projection that converts latitude and longitude into XY coordinates, a projection that is completely new and not derived from some projection.

``````def transform(lon, lat):
Some formula....
return x,y
``````

I would like to use this projection to display a map of the world, I have tried matplotlib, cartopy, and pyproj but I can't find an interface for custom projections.

• A custom projection would need more than just one direction of translation, and probably other functions as well. And the implementation would likely be in C/C++ to be compatible with existing tools. Mapping data in a new projection is as simple as converting the data to the projection and drawing it. You could attempt an OGC Well-Known Text for this new projection, but your best hope is that the WKT is ignored if unknown. Getting others to support adoption of this new projection is outside the scope of this forum. Nov 25 at 13:12
• Hi. If you want to show a raster map of the whole world, it is not so hard to do with matplotlib, but you need to know the inverse transformation too. The equations and a map to reproject are needed to answer. Nov 28 at 2:12
• @Vince Hello, I would like to know exactly how to do it, how to use the projection equation of the proj editor. This projection is brand new and I only have the positive and inverse transformations of the projection. I would like to know how to convert the 3D latitude and longitude coordinates to a planar projection coordinate system, and how exactly this process works? Dec 6 at 9:55
• @GabrielDeLuca The matlplotlib I'm using doesn't seem to support setting custom projections, is there a similar library that can help me use the new projection to display a map? Dec 6 at 9:57
• Broad, complex and multifaceted Questions are out of scope here. Your best bet it to research for a tutorial, but even that is outside Focused question/Best answer model used here, since we're more of a problem-solving site (having found a tutorial, and started implementing it, if you have an issue with one step, then you'd have a GIS SE topic). 2 days ago