Create a terrain using a plane with painted deformation or import one
In the Front View create a single polygon plane for each variety of vegetation.
Create a camera in the scene
Creating your materialIn your graphic program, create a texture map with an alpha channel using the previous tutorial or if you are a little more comfortable. Save it as a Targa or any other format that supports an alpha channel.
Make sure your active renderer is Mental Ray.
Open the material editor
Selects a new arch+ design material (don't forget to name it)
Under Templates select Matte Finish
In the Main Material Parameters, roll out under diffuse click on the button next to color, double click on the map and navigate to your image.
Under the Special-Purpose Maps rollout delay on the button next to Cutout and navigate to your alpha image or the same image (if you're using a Targa) .
In the Bitmap Parameters roll out, change the RGB Channel Output to Alpha As Gray
Click on the Go to Parent Arrow and assign the material to one of the plans
Repeat that for each variety
Setting up the particle system.
Group all the plans representing the different plants and name the group
In the fly out under the Create Geometry tab choose Particle Systems
Click the PF Source button.
In the top view drug an icon anywhere in the scene.
Type 6 to activate the particle view
Here you can see the particle system we have just created
Delete the Speed, Rotation, Position Icon and Shape nodes
From the tray below drag-and-drop into event 1 a Shape Facing, Shape Instance and Position Object nodes
Click on the Birth node and set the Emit Start to -1 and the Emit Stop to 0 (since we want all the plants to be present since frame 1) and set the amount to the number of plants you would
like in the scene.
Click on Display and change the Type to geometry
Click on Position Object under Emitter Objects Click on By List and select the object/s you want the vegetation to be on (you can see tics appearing on your terrain at this moment).
Under Location, select the distribution you desire for this tutorial. I choose vertices, however it is important to know that you can paint a selection on Emitter object and use that selection with the selected vertices option for an instance.
Click on Shape Facing under Look at Camera/Object click on the button and select the camera in the scene either from the list or by clicking on it in the viewport (this is the heart of this exercise, this makes sure that a two-dimensional image or a "billboard " will always faced the camera as we animate it through the scene)
Click on Shape Instance Under Particle Geometry Object click on the button and select your
group. Under Separate Particles for check group members adjust your scale and variation to figure scene and add realism. You can also change the seed until you get your preferred variation
Add your own lighting and Sky Dome or use Mental Ray son and sky, and you are ready to render.
Note: this type of workflow is recommended for medium and wide shots and for background objects and can be used for other types of objects, such as crowds, for an instance.
