A spherically rotatable support for a light image projector has level and/or plumb indicators for leveling or plumbing a central reference frame of its spherical rotation. A projected light image, such as a laser line segment of relatively short length may be successively stepped across a long wall while maintaining its level or plumb condition. A low powered laser or other light source may be used to generate the short-length, line segment in place of a more high powered light source that would otherwise be needed to illuminate the full length of the wall or other such surface.