Areas

Overview

The areas rollout is used to define boundaries within which items from the Geometry list are scattered. There are 5 types of areas that can be used in combination in a single Forest object:

  • Splines.
  • Objects
  • Forests
  • Paint.
  • Surfaces.

Depending on the type, an area can be set to either Include or Exclude scatter items. Include is an additive mode that creates items within the region, Exclude is subtractive, removing items from the region. The table below illustrates the modes available for each area type. 

Area Type Include Exclude
Spline (tick) (tick)
Object   (tick)
Forest   (tick)
Paint (tick) (tick)
Surface (tick)  

Surfaces allow you to scatter items on uneven surfaces, it is possible to toggle surface on and off from the areas rollout but adding new surface areas and editing the parameters is handled in a the Surfaces rollout.

 

Procedures

To create a new Forest object based on a spline

  1. Open the Create panel and select iToo Software from the object subcategory list.
  2. Click  and then click any spline in the viewport. 
  3. Open the Modify panel and make any necessary adjustment to the spline's settings from the Area rollout.

To create a new Forest object based on a  surface

  1. Open the Create panel select iToo Software from the object subcategory list. 
  2. Click  and then click a surface in the viewport.
  3. Open the Modify panel and make any necessary adjustment to the settings from Surface rollout.

To add a new closed spline area

  1. Open the Areas rollout. 
  2. Click  found below the Areas List.
  3. Pick a closed spline from the scene. 

To add a new open spline area

  1. Open the Areas rollout. 
  2. Click  found below the Areas List.
  3. Pick an open spline from the scene. 
  4. Adjust the Thickness value to define the width to scatter objects either side of the spline. 

To add a new paint area

To use a paint area you must also have a Surface area set to XY mode but this should be switched off in the Areas list to restrict the scatter to only the painted regions.

  1. Open the Areas rollout. 
  2. Click  found below the Areas List.
  3. Click  to open the Painter Settings.
  4. Set the Min and Max brush size, if you are using a tablet turn on Enable Pressure Sensitivity to use pen pressure to control the brush size.
  5. Click  and paint on the surface in the viewport.
  6. Click  and paint on the surface in the viewport to erase paint areas.

To convert a paint area to splines

  1. Click .
  2. Modify the spline using 3DS Max's standard spline modelling tools.
  3. If necessary, click  to restore the spline to a paint area (This can be done with any spline object).

To exclude scattered items using splines

In order to work correctly, exclude areas need to be above an include area in the Areas List. To change the order order of areas use .
 

  1. Open the Areas rollout. 
  2. Click  found below the Areas List.
  3. Pick a spline from the scene, if it is an open spline enter a Thickness value.
  4. Click Exclude.
     

To exclude scattered items using an object

  1. Open the Areas rollout. 
  2. Click  found below the Areas List.
  3. Pick any geometry object from the scene. Where the object overlaps an include area the scatter items will be removed.
  4. To improve accuracy for large scenes increase the Resolution value (default is 512px). 
  5. To Increase or decrease the distance between scattered items and the object, adjust the Scale value.
     

 

You can also use groups but this is recommended only when the objects are close together. If you need to use multiple objects that are a large distance apart, assign each one as a separate area.

To exclude scattered items using another Forest object

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  1. Open the Areas rollout. 
  2. Click  found below the Areas List.
  3. Select a Forest object from the scene. 
  4. Adjust the Scale value if necessary to change the exclusion size around each tree.
  5. Change Falloff > Exclude values for Density and scale (see below).

To create a separate region around the base of each tree.

  1. Clone the Forest Object use in the last steps
  2. Select the the Forest area from the list and click on Invert Curve.
  3. Adjust falloff, Add Geometry items and Distribution Map as required.

To add scale and density falloff along a boundary

Using falloff controls it is possible to affect the density and scale of objects near an area's boundary. 

  1. Click Falloff > Density and Falloff > Scale.
  2. Enter Include Range values to define the distance affected measured from an include area's boundary. 
  3. Enter Exclude Range values to define the distance affected measured from an exclude area's boundary. 
  4. The default falloff setting is linear, to change the falloff curve click .
  5. The falloff graphs have the range on the X Axis (from 100% to 0 %) and the Scale or Density percentage on the Y Axis (from 0% to 100%).
     

To add scatter items around the perimeter of an exclude object

  1. Add a Spline, Paint or Surface include area.
  2. Add an Exclude area above the include area in the Areas list.
  3. Turn on Falloff > Density and/or Falloff > Scale and enter an Exclude Range value.
  4. Click Invert Curve. This will reverse the effect of the falloff curve generating items only around the perimeter of the exclude object. 

To override the geometry used in an individual area

  1. Select the Area to parameterise from the Areas List.
  2. Click Plants > Select Models.
  3. Click  and tick the models to use from the Select Models menu. Click OK. 
      

To limit the scatter using material IDs

  1. For this feature to work, a Surface must be assigned in the Surface rollout and Forest must be set to X/Y Mode.
  2. In the Mat. ID list box, enter the Material ID numbers of the faces you wish to use to scatter objects
  3. To add multiple IDs simply add a list, ensuring there is a space between each value.
     

To override the distribution map used in an individual area

  1. Adjust the scale of the distribution map by adjusting Override Dist. Map > Scale.
  2. Adjust the density of the distribution map by adjusting Override Dist. Map > Threshold.
  3. Apply a new distribution map to the selected area by dragging a map to the Distribution Map Slot
     

To prevent scattered items from "leaking" outside an area perimeter 

  • For V-Ray users, set Boundary Check mode to Edge

    Please be aware that Edge Mode is not compatible with V-Ray proxies.If you wish to reduce file sizes and use Edge Mode it is recommended to use XRef objects instead.


  • For Mental Ray and Corona 
    1. users, set Boundary Check mode to Edge
       
    2. Add a Forest Edge map to the Opacity or Cutout  map slot of all the object's materials. You can automate this process for objects with large numbers of materials using the Material Optimiser tool.

  • For all other renderers, set Boundary Check mode to Size. To create large areas with well defined boundaries, please refer to the Grass Edges tutorial.
     

Interface

Areas List

The areas list details all the items being used to define the scatter region. The order is important, areas are processed from the bottom of the list upwards, an exclude area will only affect areas that are below it in the geometry list.

  • The areas are not available when working on Custom Edit mode or using UV Surfaces.
  • It is important not to overlap multiple Include areas. Overlapping areas duplicates geometry and the issue is not always obvious in the viewports, but you may get strange results in the render because of the coplanar faces.
Icon Name Description
Add spline area Adds an include/exclude area defined by a spline object.
Add object area Adds an exclude area defined by a geometry object.
Add forest area Adds an exclude area defined by a Forest Pack object.
Add paint area Adds an include/exclude area by painting a spline using the mouse or tablet
Delete selected area Removes the selected area.
Add multiple areas Adds multiple areas from a list.
Move up

Move the selected area up.

Move down Move the selected area down

Selecting an area from the list will change the available options in the Properties group. Some properties are common to all types of areas, while other are unique:

Spline Area Properties

On

When active turns the current area on. If unselected the area will be ignored when calculating the scatter regions.

Name

The name of the area. Default behaviour is to inherit the name of the source object but it can also be edited manually.

Include

When active the area creates items within the region defined by the spline.

Exclude

When active the area removes items within the region defined by the spline. Only items generated by areas below it in the Areas List will be affected.

Spline

Displays the name of the selected spline. Click this to pick a new spline from the scene.

Thickness

Used with open splines to define the width of the path in which items are scattered.

Convert to Paint

Converts the Spline area to a Paint area.

Object Area Properties

Object areas allow you to use any geometry to exclude scattered objects. Object areas are optimised for high polygon models and work by generating a black and white bitmap map by projecting the geometry onto the surface along the world Z axis.

Object

Displays the name of the assigned objects. Click this to pick a new object from the scene.

Top Limit

Defines a height above which the object's geometry is ignored when calculating the exclusion map .This feature is typically used for objects that are wider at the top than at the bottom.
 

Resolution

Defines the size of the bitmap. Higher numbers result in greater accuracy typically required when using large models. Default value is 512px.

Scale

Scales the exclusion effect. Values of less that 100% will move scattered items closed to the object, values greater that 100% will push scattered items away from the object.

Forest Area Properties

Forest objects work in a similar way to Object areas allowing the use of a Forest object to create an exclude area.

Forest

Displays the name of the assigned Forest object. Click this to pick a new forest from the scene.

Shape

Select from Sphere or Mesh to define the geometry used to create the exclusion effect. Sphere use a virtual bounding sphere that is much faster though less accurate. The size of the sphere can be adjusted using the Scale value of the area or by changing the Collision Radius parameter for the Items found in the Geometry Rollout.

Mesh mode uses the full geometry to calculate the exclusion effect. The approach is more accurate but can be slower when using dense geometry.

Resolution

Defines the size of the bitmap. Higher numbers result in greater accuracy typically required when using large models. Default value is 512px.

Scale

Scales the exclusion effect. Values of less that 100% will move scattered items closed to the object, values greater that 100% will push scattered items away from the object.

Paint Area Properties

Paint areas allow you to paint include and exclude regions with a mouse or tablet directly onto the terrain. Paint areas require a Surface set to XY mode.

Include

When active the area creates items within the region defined by the spline.

Exclude

When active the area removes items within the region defined by the spline. Only items generated by areas below it in the Areas List will be affected.

Paint

Paint on a surface in the viewport to add to the current area.

Erase

Paint on a surface in the viewport to subtract from the current area.

Settings

Click to open the brush settings. From this menu you can adjust the size and pressure sensitivity of the brush and erase modes.

Preview Falloff

When active the falloff effect is visible while painting (enabled by default).

Convert to Spline

Converts the Paint area to a Spline area.

Surface Area Properties

Due to the large number of options the majority of the surface areas settings are found in a separate Surfaces rollout. They do however display in the Areas List and can be toggled on or off from the Areas rollout.

On

Turns the surface on or off.

Surfaces are often used to define the scattered item's position on the Z axis in conjunction with splines and paint areas to define the region on the X and Y axes. Occasionally you may find that the full terrain is filled with items,even though there are spline areas in the Items List. If this is the case the usual problem is because the Area is on, when using surfaces with other Include areas it is important to turn the Surface off.

Common Properties

These properties are found in all area types.

Select Models

When active the selected area uses a subset of the models from the Geometry list defined in the Pick menu

Pick

Opens the pick menu. When Select Models is active the current area will use only the models ticked in this list.
 

Override Distribution Map

Used to override the global distribution map.

Scale

Scales the distribution map only for the selected area.

Threshold

Adjusts the threshold only for the selected area.

Material ID

Limits the scatter surface to use faces with only the material IDs listed. To use multiple IDs, simply leave a space between them.

Falloff Affect

Adjusts the strength of the density and scale falloff curves. Setting this value to zero disables the effect completely.

Invert Curve

Inverts the falloff curve. Commonly use to create scatter items around boundaries and the perimeter of exclude areas.

Boundary Checking

Forest Pack 4.3 can use 3 potential modes to determine if an object falls outside of the scatter area and is removed.

  • Point: Uses the item's pivot point to check if outside the scatter area. If true the entire item is removed and you may get overlaps.
  • Size: Uses the item's width and collision radius to check if outside scatter area. If true the entire item is removed and you won't get overlaps but the boundary can be uneven if the item's size is too large.
  • Edge (V-Ray only): Uses the lowest Z Vertex of each of the item's individual elements to check if outside the scatter area. If true only the individual element is removed creating a clean edge, without slicing the geometry. Note that when using edge mode, an element is defined as a group of connected faces that share the same material ID. These are the same elements used by Forest Color.

Edge Mode does not preview in viewports

To improve viewport performance edge trimming is calculated only at render time. This means the effects of the this mode will not be previewed in the viewports. However, previews can be enabled by holding down the left CTRL key and clicking on the Edge radio button.

Please be aware that Edge Mode is not compatible with V-Ray proxies.If you wish to reduce file sizes and use Edge Mode it is recommended to use XRef objects instead.

Falloff

Density

When on, items will change density as they approach a boundary. The distance from the boundary is controlled by the include and exclude range values and the density is defined by a falloff curve.

Scale

When on, items will change scale as they approach a boundary. The distance from the boundary is controlled by the include and exclude range values and the density is defined by a falloff curve.

Edit Curve

Edits the the falloff curves for the density and scale effect. There are separate curves for scale and density.
 

Include

Sets the range for the falloff effect on the perimeter of Include splines and surfaces.

Exclude

Sets the range for the falloff effect on the perimeter of Exclude objects, forests, and splines.

Affect Height only

When on the scale falloff effect only affects the height of the items. Dimensions on the X and Y axes remain unchanged.