Decal documents consist of a group of several areas defined on the ground, onto which you want to apply some local modifications. For each decal area, you can modify the soil, the plant densities, the elevation, etc..., which enables you to customize it.

Creating a decal document

To create a decal documents, open the decal treeview. Then create a new decal document, name it, and drag & drop it to the current scene. You can double clic on the document to open its view.

The view of the decal document is divided in two sections :

Creating a decal area

Once your decal document is created and placed in the current scene, you will want to create your first decal area by clicking on the "Create a new decal area" button at the bottom of the area list. A new area will appear in your list.

To define this new decal area using some curve points, you need to :

You can delete decal areas or curves points using the trash bin button. Select the object that you want to delete in the decal areas list view or in the viewport, then click on the delete button.

You can change the way points are added to an existing decal area curve. We have two modes defining how a new point is added to the existing curve : "Continuous contours" and "Closest Segment". You can switch between the two modes using the button next to the trash bin.

Refining the area

Once you have your curve points placed, you can change the shape of the global curve. You have 4 options :

For "Bezier path" and "Straight path" curves, you can choose the width of the path using the width slider. It is expressed in meters and is the total width of the path (not the half width).

Finally, you can setup your falloff width for all shapes. The falloff width defines a border inside the decal area where all the modifications (soil, plant densities..) will be blended smoothly with what was defined outside of the decal.

Decal Properties : Modifying the terrain

First set of parameters allows you to modify the terrain in the decal area, and is composed of two parameters : Height offset and Flatten terrain.

Height offset (m) : an elavation offset in meters used to elevate or dig the ground inside the decal area. The positive values will add elevation to the ground, while the negative values will dig the ground.

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Applying an height offset

Flatten mode : There are 3 modes for the flattening of the terrain :

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Flatten terrain

Decal Properties : Applying a soil

Second set of parameters allows you to add a custom soil to your decal area. If no custom soil is set, the soils from the terrain under the decal area will be kept.

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Soil elevation only

Decal Properties : Customizing the vegetation

Third set of parameters allows you to customize the vegetation in your decal area.

Biome: Select a biome document to apply to your decal area. You can also drag & drop a biome document inside the decal area directly in the viewport.


A limitation is that the "Color Fade" and "Density" sections of the biome will not be applied for a biome inside a decal area. The parameters chosen for the scene biome are applied to all the biomes in the scene, including those in the decal areas.

You can adjust the densities of the different plant categories inside your decal area using the following parameters :

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Density Offset

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Density Minimum

Use Soil Densities:Check to use the soil's density channels instead of the terrain density. It is only possible if a soil document has been specified above in the "Soil" parameter.

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Use Soil Densities

Grid plantations

If you don't want any randomness in your plantations, you can use the decal grid constraints. For one or several plant categories from the biome, the grid overrides the usual density constraints, making the plants spawn exactly on the grid.

Creating a hole in your decal area

A hole is another area defined by a curve, and located inside your decal area, where the properties of this area will not be applied. You can create as many holes per decal area as you want.


Limitation : Holes do not work on decal areas with the "Curve Type" set to "Bezier Path" or "Straight Path". You can create them but they will have no effect.

To create a hole, you need to :

Creating a hole


If a hole is created outside it's parent decal area, it has no effect. A hole only has effect on it's parent decal area, and will have no effect on another decal area.

Ordering decal areas

If you create several decal areas in the same decal document, you can define the order in which they will be applied. The highest decal area in the list corresponds to the "top" layer, which means it will be applied on top of all others. To reorder them, just drag and drop the decal areas in the list.

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Reordering Decals

You can chose the behavior of each decal area in regards with the ones located under (in the list) :

To change the blend mode of a decal area, you need to :

Blending modes