Environment Series 2: Grass



Hey guys, today we have part 2 in the environment series.
This series is based around nature and cycles.

Bear in mind that this is NOT a beginner series,
I will assume you already know what I mean when I say Duplicate the trees around the place and randomize the rotation and scale a bit.
Of course Beginners will still be able to follow along but be ready to do a bit of googling ;)

So the theme is: “Environments”

So we will be doing a 8 part series on modelling an environment scene, you may have already seen the teasers on facebook, but if not you can jump there now :D
facebook.com/cgtutorials
So why so many parts for one scene?
Well basically this is going to be reference material, so you can just jump to a section you need to refresh on.
What will be covered?

1. Landscaping: The ground, path, river, and background
2. Grass: The grass, flowers, and butterflies
3. Bridge: The old bridge
4. Well: The old Well
5. Trees: All the Trees
6. House: An old fashioned cottage
7. Ivy: We cover everything in Ivy
8. Finish: Touch-ups, Compositing etc

So Lets get started, For this tutorial you will need a current cycles build from graphicall.org, and it doesn’t matter if you can render with GPU or not, unless you have 6Gb of Graphics ram you are gonna be stuck to the CPU anyway. Currently cycles does not support strand rendering and therefore all grass is required to be poly.

1a: First we have to model a single blade of grass.
Add in a plane and shape it to a tall thin plane with the origin at the base. Remember the thinner it is the more realistic your grass will be, but the more strands you will need. Also you should add two edge loops vertically and UV unwrap to the grass image texture provided(grass_blade.jpg), You will likely need to rotate the uv by 90° and scale to fit.
If you would like to create your own grass texture, notes are to make the base black, and the tip a pale yellow/white. this will help fake AO, and brighten it up a lot because the blades don’t recieve a lot of light.

1b: Now that it is unwrapped we can begin making it look like grass, make the base and tip sharp by moving the vertices close together and give it some deformation, you will want to create at least 5 varieties.
Add all these to a group and call it grass.

2: Alright now the grass is modelled we can work on the texturing. This is a fairly easy node setup. We have three textures, grass_blade.jpg(diffuse), grass_blade_bump.jpg(Displacement), and grass_blade_alpha.jpg(Transparency).
The transparency map is used to fade out the base and tips of the grass blade to make it look a lot more natural.
In the node editor, load in a texture cooordinates node and link it to the three images.
Add in a Mix shader and mix together a translucent and transparent shader, we will use the alpha map to determine which parts of the blade are transparent and which is translucent. (translucent means light will light up the other side as well, where as transparent just lets light pass straight through.)
Connect the diffuse to the colour of the translucent, and leave the transparent shader color pure white. (White=transparent,Black=opaque).
Ok so now for the bump, you will want to pass it through a multiply node(math node) with a small value of about 0.02 and plug it into the displacement, it will be barely visible, but adds a nice touch.
Final Node setup and preview:

3: Ok before we add our particle system, we need to add in a vertex group for the density of the grass. Go into top view, and scale your camera all the way up, now assign the entire ground plane a full weight, and remove the areas where the path is, the river, and remove the area outside the camera cone because we can’t see those anyway. also when doing the path try to have the edge as sharp as possible.

4: Sweet, lets start on the particle system.
This is a bit finicky to get right, Set up a hair particle system with random distribution(make sure your in advanced mode) and bump the amount up to about 10000, you will need to tweak that value depending on how thick you want your grass.
The important one is under rotation, set the axis to global Z and play with the phase, and give it a bit of random rotation.
If you can’t get the blades to stand up, you may need to rotate your grass.
I rotated my grass blades 90° around the X-axis and applied rotation.
When it comes to the height of the grass, it’s personal preference, you can control the size under ‘physics’, A size of 1 worked for me.
Under Render make sure you have your grass group selected and pick random checked.
Save your file now.
And under children choose interpolated and bump the count up to 60.
When your happy with how it looks in the viewport take display down to 0 or turn the particle system off in the modifiers panel.
And finally for density choose the vertex group we made earlier.

5a: Ok so we have grass. but have you ever seen a field of grass without flowers and butterflies?
Flowers:
Add a plane and in tessalate(convert to tris) in edit mode(CTRL+T), and unwrap. Give it a basic texture. We will mix together a diffuse and transparent shader with an alpha image for the mix factor. You can get these textures from cgtextures and make an plha texture in an image editor. (remember black:opaque,white:transparent)
Duplicate a blade of grass and join it to the flower, you will need to fix up the uv’s a little. and make a few varieties. I have 4 white to 1 yellow

5b: Ok so lets do some butterflies.
Import a image of a butterfly as a plane and place an edge loop in the center, fold the two sides up to bend the wings and give it the same shader as the flower(with the butterfly of course) ang make a couple of varietes, you might even want to have some sitting on the flowers.
Add all the flowers and butterflies to a group.

6. Ok so we now need to add a particle system for the butterflies and flowers. duplicate the grass settings and remove children(set to 0).
change the group to the flowers/butterflies, you can play with the count as well, obviously there isn’t going to be swarms of butterflies everywhere, and play with the size until the flowers are only slightly taller than the grass.

Ok let’s give that a render with all the particle settings on and this is what you should get:

So I hope you enjoyed this tutorial, and stay tuned for part 3 where we look at building and texturing the old bridge!

Got stuck? Leave a comment below

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