I would like to change SpherePoint.getVector() to return a sphgeom UnitVector3d instead of a lsst::afw::geom::Point3D. Conceptually this change makes sense because it is a unit vector that is being returned.
Pragmatically it will help us replace geom with sphgeom as part of implementing
The only usage of geom in our stack is for creating convex polygons by calling convexHull. This function exists in both geom and sphgeom, but the sphgeom version is written in C++ and so is picky about its inputs: it wants a std::vector<UnitVector3d>.
This change will not be very disruptive.
Existing Python code will need no changes because in all cases the vector simply needs to be an indexable sequence of 3 floats (even when calling the geom version of convexHull).
There are a few C++ files that will need to be changed, but the changes are very simple and, in at least one case, result in simpler code.