Synopsis
		sfcheckerboard > Fo.rsf nx=1 ny=1 nz=1 ox=0.0 oy=0.0 oz=0.0 dx=1.0 dy=1.0 dz=1.0 N=1

Parameters
		int N=1 ------------------------------------------------------------   float dx=1.0   float dy=1.0   float dz=1.0 get checkerboard size   int nx=1   int ny=1   int nz=1   float ox=0.0   float oy=0.0   float oz=0.0