Scatter

A scatter covers a surface with copies of your components: grass on a lawn, trees on a hill, pebbles on a path. The copies only exist in the render, so your SketchUp model stays light and fast, even with a million of them. The render window calls the copies instances.

For a lawn, you can also paint it with the Grass material instead: it grows real blades of grass without any components.

Everything in this forest that isn’t the ground or the water is a scatter: more than 230,000 trees, saplings, ferns, grass clumps, rocks and stones, from a SketchUp model with one copy of each. See Example: a forest pond for how it’s made.

Scatter or Skatter?

Scatter is built into Rayscaper: you set it up in the render window, and it’s what this page is about. Skatter is a separate SketchUp extension by Lindalë, with its own toolbar and settings. You don’t need Skatter to scatter with Rayscaper, but if you use it, Rayscaper renders its compositions too, see Using Skatter with Rayscaper. The two work side by side in the same model.

A scatter is made of two things you pick in SketchUp:

• Surfaces: the groups or components the copies are placed on.
• Objects: the components that get copied.

Everything else, like how many copies and how much they vary, is set in the Scatter section of the Scene Editor.

Video

Fill a garden with plants scatters four plants over the planting beds of a villa garden. It picks the garden as the surface and the plants as objects, and limits the scatter to the faces painted with the bed material. Then it sets the density, and paints a new bed in SketchUp that the plants follow. To follow along, download its scene, rayscaper-scatter.skp (8.7 MB): a modern villa whose lawn and shrub border are scatters already, with one plant of each kind in a bed. It works with the free version of Rayscaper.

Create a scatter

Rayscaper has to be rendering, because the render window does the scattering.

1. In SketchUp, select the group or component to scatter on, for example your terrain.

2. Right-click it and pick Rayscaper > Scatter on Selection. The render window opens the Scatter section with a new scatter.

3. Select the components to scatter, for example a grass clump and a flower.

4. Right-click them and pick Rayscaper > Add to Scatter as Object. The copies show up in the render.

You can do the same from the render window: select in SketchUp, then press Scatter on SketchUp Selection or one of the Add SketchUp Selection buttons in the Scatter section. New Empty creates a scatter without a surface and objects, which you add later.

To copy or remove a scatter, select it in the list at the top of the Scatter section. Then press the copy or trash button below the list, or right-click it in the list and pick Duplicate or Delete. Click its name to rename it. The eye next to it turns it off without removing it.

To remove a surface or an object from a scatter, click the × next to it.

Tip

The component you pick as an object is only a template. Put it anywhere, or hide it, and the scatter keeps working.

Surfaces

Setting	Description
Materials	Limits the scatter to the faces with the checked materials. With All materials the whole surface is used.
Add SketchUp Selection	Adds the groups and components selected in SketchUp as surfaces.
Add Loose Geometry	Scatters on the faces of the model that aren’t part of a group or component.

The material is the easiest way to decide where a scatter goes. Paint the lawn with a grass material and the path with gravel, check the grass material in the Materials list of the surface, and the path stays clear. Check more materials to scatter on more of the surface, like a forest that covers the forest floor and the meadow. Repaint a face with the paint bucket in SketchUp and the scatter follows.

A surface has to be a group or component that isn’t nested inside another one.

Objects

Every object has a Weight: how often it’s picked compared to the others. An object with weight 2 shows up twice as often as one with weight 1. At weight 0 the object stays in the list but isn’t scattered.

Faces of an object that aren’t painted take the material of the component you selected, the same way SketchUp shows them.

The colored square next to an object is its color in the preview in SketchUp.

Distribution

Setting	Description
Mode	Projection places the copies on the surface from above. Wrap covers every face of the surface. See Projection or Wrap.
Density per m²	Number of copies per square meter of surface.
Seed	A number that picks a random arrangement of the copies. Every seed gives another arrangement, the same seed always the same one.
Instance Limit	Upper limit for the number of copies. The density is lowered when the surface would get more.

The Result section at the bottom shows what the scatter made: the number of Instances and the Surface Area it covers. When the Instance Limit lowers the density, it says so, with the density it uses.

Projection or Wrap

Projection is made for lawns and terrains. The copies come down on the surface from above, like rain. So only the parts you see from above get copies. The underside of a ball, the ground below an overhang and upright walls stay empty. The copies stand on the upper side of the surface, whichever way its faces are turned in SketchUp.

Wrap is made for shapes you want to cover all around, like a topiary ball or a mossy boulder, and for walls. Every face of the surface gets copies, on its front. When copies end up inside a shape or behind a wall, the face is turned the wrong way: right-click it in SketchUp and pick Reverse Faces. Set Follow Surface to 100% to make the copies point away from the faces. At 0% they stand upright on every face, also on the underside of a shape.

Variation

Setting	Description
Smallest Scale, Largest Scale	Every copy gets a random size between these.
Rotation	Copies are turned around their up axis by a random angle up to this. 360° gives every direction.
Follow Surface	At 0% the copies stand upright, like trees on a slope. At 100% they stand perpendicular to the surface, like grass.
Swap Y and Z	The green axis of the objects follows the surface instead of their blue axis, and their blue axis stays upright. See Green walls.
Height Offset	Moves the copies up or down. Sink them a little to hide their base in uneven ground.

Green walls

To cover a wall with plants, use Wrap, since Projection leaves walls empty, and set Follow Surface to 100%. The copies then stick out of the front of the wall, which suits moss, leaf clusters and ferns. Height Offset moves them out of the wall or sinks them into it. A wall with thickness gets copies on all its sides, so paint the side you want and check only that material under Surfaces.

Plants that hang down or climb, like ivy, are modelled upright and have to lie flat against the wall. Check Swap Y and Z for those. The copies stay upright on every wall, with their green axis pointing out of it. Rotation then makes them lean to the left and the right by up to half its angle, so keep it small.

Preview in SketchUp

While Rayscaper is rendering, the SketchUp viewport shows where the copies are. Small scatters are drawn as boxes with the size of each copy, large ones as points. Every object has its own color, the one shown next to it in the Scatter section. For very large scatters the viewport shows a part of the points, the render always has all of them.

Turn the preview off in SketchUp’s Overlays panel, where it’s listed as Rayscaper Scatter Preview.

Example: a forest pond

The forest pond at the top of this page is one SketchUp model. The terrain is a single group, painted with five materials: forest floor, meadow, pebble shore, pond bed and a footpath. The pond is one flat face with the Water material that the banks of the terrain cut to shape. Next to the terrain stands one copy of each component, on a tag that’s hidden for the render.

Seven scatters, all with the terrain as their surface, fill it in. The material of each surface decides where the copies go:

Scatter	Materials	Objects	Density per m²	Follow Surface
Conifer forest	Forest floor	3 pines, 3 firs	0.03	0%
Saplings	Forest floor, Meadow	4 young pines and firs	0.035	10%
Ferns and deadwood	Forest floor	3 ferns, 2 dry branches	1.3	80%
Meadow grass	Meadow	5 grass clumps, a fern	45	70%
Boulders and stumps	Forest floor, Meadow	6 mossy rocks, a boulder, a stump, a fallen trunk	0.006	90%
Shore pebbles	Pebble shore	13 rocks and stones	1.2	100%
Pond bed stones	Pond bed	7 stones	0.25	100%

The trees stand upright on the slope, the rocks and stones follow it. Nothing is scattered on the footpath, so it stays clear without any extra work, and the copies on the bed of the pond show through the water.

The trees, saplings, ferns, grass, rocks, stumps and branches, the ground textures and the sky are CC0 assets from Poly Haven. The trees are reduced to about 60,000 to 130,000 triangles each to keep the SketchUp model light.

Large scatters

• Every copy stays in the render, however far it is from the camera. Rayscaper doesn’t leave out copies in the distance.
• The copies share the geometry of their component, so a million copies of a grass clump don’t need a million times its memory. Each copy still takes a little memory, so the memory grows with the number of copies and with the size of the components and their textures.
• When a scene gets too heavy, lower Density per m² or Instance Limit, or use components with fewer triangles. The forest pond renders more than 230,000 copies.
• For large scatters, the SketchUp preview shows only a part of the copies. The render always has all of them.

Good to know

• Scatters are saved with your SketchUp model, together with the other Rayscaper settings.
• When you move or edit the surface, or edit a scattered component, the scatter updates.
• The copies can’t be selected or edited one by one, and they aren’t part of the SketchUp model.
• The pick tools of the render window (focus, material) see through the copies to what’s behind them.