@Lynn22: thanks for your suggests. i already tried some poligonal grass from sketchup models, but nothing really satisfied me. everything seems so flat, or even unreal...
@Hansmex: Hi Hans, i'm glad you like the picture. i've tryed rendering other day times, but the scene seems even most unrealistic on 12 AM or others. is there a way to have more control on Sunflow parameters? do you have suggestion too for a more tesselated grass? thanks!