Country outlines
Time-zone outlines
Deferred-creation objects? (e.g. antipodal orbit)
Suitable infrastructure for rendering that depends on pixel-distance or mapped curvature? -> Dynamic subdivision


Outline algorithm:

For each contour, transform to display space. Clip this on viewport
edge, and on projection edge.  

For each scan line, find intersections of the contour lines with the
scan line, and sort them.

Keep a sorted list of "active" layers. Run across the scanline, adding
& removing layers from the list. When top layer changes, change colour
of rendering. (This is O(intersections*log(layers)) complexity).

- What happens when a line leaves one edge of the projection and comes
  in another? How do we identify this? Deal with it?

- Data structure: outlineset = vector<contour>
		  contour = colour + vector<point>