The options in this rollout are active when the scattering mode is set to 2D - On Surfaces.

Distribution – Specifies the distribution mode of the objects. See the Distribution example below for more information on how the two modes compare.

Random distribution – This mode scatters instances randomly on all mesh objects. It is enabled by default.
UV Map – This mode uses UVW mapping to scatter instances in regular patterns.

Map Channel – Determines which UV map channel is used for the scattering when UV Map Distribution mode is selected.

Map Channel Name – Specifies the UV Map Channel name.

Planar Mapping – When enabled, simple planar UVW mapping is applied to the distribution object and used instead of its existing UVW channel. This mode is only available with the UV Map Distribution mode.

Proj. Axis – Determines which axis is used for the instance scattering.

Count – Defines an exact number of instances to scatter - either overall, or per area in the case of scattering defined by density (Per Square option). The number is always limited by the Instance Count Limit option. See the Count example below for more information.

Per Square – When enabled, the number of instances to scatter is defined by density (Count per square having the given edge length). The number of instances is always limited by the Instance Count Limit option. See the Per Square example below for more information. 

Square Size – The specified value is the edge length of a square defining an area for computing the scatter density. The length is measured in world units.

Density Texture – Allows a black-and-white texture map to be assigned. The map determines how the instances are scattered on the surface. User attributes can also be assigned to determine the scattering.

Example: Count

For this example, the Per square option is disabled.

Example: Per Square

For this example, the Per square option is enabled.

Pattern – Determines a pattern for the scattering. See the Pattern example below for more information.

Grid – Rectangular grid.
Running Grid – Rectangular grid with every other row offset by half of the grid spacing.
Hexagonal Grid – Arranges instances into hexagons.

Lock V – When enabled, the values of the V coordinate for Spacing, Jitter and Offset are locked to the U coordinate's values. See the Offset examples below for more information.

Spacing – Scales the pattern in UV space. When Spacing is set to 1, the pattern occupies the whole space. When Spacing is set to 0.5, the pattern is repeated twice. See the Spacing example below for more information.

Jitter – Determines what percentage of the instances are randomly placed. When Jitter is set to 0, all instances are placed according to the UVW mapping. When Jitter is set to 1, all instances are randomly placed. See the Jitter example below for more information.

Offset – Offsets the pattern by the given value. Keep in mind that 0 and 1 Offset gives the same result, as 1 moves the pattern by one whole repetition. See the Offset examples below for more information.

Example: Pattern

This example shows the difference between the three Pattern options. The Spacing for all of them is set to 0.1.

Example: Spacing

For this example, a Grid Pattern is used for all renders. The second set of images shows the Lock V option disabled and the U and V get different values.

Example: Offset by Single Axis

For this example, the Pattern is set to Grid. Here, the offset is applied to the V axis only (the Lock V option is disabled).

Example: Offset Locked V

For this example, the Pattern is set to a rectangular Grid. The offset here is applied to both the U and V axes (Lock V option is enabled).