Hello Sarada,
You can use custom origins and steps for the grid surface X and Z coordinates. You can set the origins to be negative values:
NGridSurfaceSeries surface = new NGridSurfaceSeries();
surface.UseCustomXOriginAndStep = true;
surface.UseCustomZOriginAndStep = true;
surface.StepX = 1;
surface.StepZ = 1;
surface.OriginX = -5;
surface.OriginZ = -5;
Best Regards,
Nevron Support Team