Generating Heightmap on Gazebo 2.2

I tried generating heightmap to model a terrain. Below is a sample terrain map generated using Gimp (129 x 129) (alpha channel removed).  However I could get only a part of the terrain getting generated.  My model.sdf truemodel://heightmap/materials/textures/heightmap3.png1 1 10 0 0falsefile://media/materials/textures/dirt_diffusespecular.pngfile://media/materials/textures/flat_normal.png1file://media/materials/textures/grass_diffusespecular.pngfile://media/materials/textures/flat_normal.png1file://media/materials/textures/fungus_diffusespecular.pngfile://media/materials/textures/flat_normal.png12545model://heightmap/materials/textures/heightmap3.png1 1 10 0 0