Converts the given gisCoordinate3D into a corresponding coordinate in the 2-dimensional coordinate system defined by the wall of a vault or a manhole, etc. The upper left corner of the wall is taken to be the origin of that 2D coordinate system, and we expect all of the stuff on that wall to lie in quadrant IV of that 2D coordinate system (i.e. the Y values will all be negative and the X values all positive).