In addition to bringing up a GUI, the OpenSCAD executable creates snapshots of rendered .scad files.

Here is a sample invocation:

    $ /cygdrive/c/opt/openscad/openscad-2015.03-2/openscad -o out.png --camera=0,0,0,0,0,0,350 space-invaders-scenes-CUSTOMIZER.scad

--camera

    the last parameter is the distance away from the object