"Creating grass land using pflow" by Ranjit Menon

5. Click on the Position Object operator, on the right side u can see its properties in the Emitter objects rollout. Click add and select the terrain. U will see that the name of the plane( Terrain) appears in the dialogue box there. See to it that the Lock On Emitter option is also ticked or else the particle will fly off when u play with the animation slider.

6. Change the Shape operator to Shape Instance operator, after that Click on the Shape Instance operator in the event and in the properties on the right side, click on the none button under particle geometry and select the grass1. U can see that lots of ticks get scattered all over the plane. Click on the Display operator and in the type select Geometry which will reveal the grass mesh. You can also change the color to green or apply a material by adding a material dynamic operator.

U can see that all of the grass blades are bend in different directions and some even go under the terrain.To rectify this Problem. Click on the Rotation operator and in its properties change the orientation matrix to world space. Which aligns the particle according to the world axis and makes it stay perpendicular to the terrain.

7. This seems a bit unrealistic cause all grass are standing upright and steady like an army of soldiers :) so to break the monotony u can first click on event 01 and right click and select copy and paste it anywhere in the open space nearby, which will create another event 02. Delete the birth operator of event 02.