About existing packages
OGC-Pharo model
User guide
Some great and useful websites to understand how projections, map visualisation and spatial computation work :
Measuring distances and areas when your map uses the Mercator projection, esri.com
Coordinate Systems: What's the Difference?, esri.com
Cartography Guide "A short, friendly guide to basic principles of map design", axismaps.com
Measuring Distances and Why Projections Matter (+ Practical Examples), gis-ops.com
