I'm working on a fantasy world; a map, to be more specific. I basically just started to paint a world map in Photoshop, but over time it became very big an unfortunately Photoshop is not really good with detailed world maps.
So I went out to look for another software to manage coastlines, rivers, cites, town, borders, streets and much much more. I decided to use QGIS, imported my .psd as .tif and started to vectorize it manually (yes, it took me quite long and I haven't finished yet).
The world map is a projection of a real planet. I never set up any CRS. The problem is, I never thought of any projection-issues before. Later I decided, that the painted map is a "Mollweide" projection of my planet. (I know this will cause some distortion, but that's okay)
To make it easier, I decided the planet to be a perfect sphere with r=10567km.
Since I am a newbie on QGIS, I have three issues now:
- I have no good idea, how to define a custom CRS and there is no tutorial for doing that.
- I have no idea how to georeference my vector layer. I worked on a mathematical way to transform the mollweide-x,y-coordinates in QGIS to real latitude-longitude-coordinates. But I don't know how to perform the algorithm on my shapefile (I thought of exporting it to GeoJSON) and get QGIS that to display the geocoordinates using my custom CRS after transforming.
- Is there a way to keep my background raster layer after transforming the vector layer so I can go on vectorizing?