Inflation Layer Parameters

This layer places an exponential decay functions around obstacles to increase cost to traverse near collision. It also places a lethal cost around obstacles within the robot's fully inscribed radius - even if a robot is non-circular for optimized first-order collision checking.

<inflation layer> is the corresponding plugin name selected for this type.

`<inflation layer>.enabled`

Type: bool Default: true: Whether it is enabled.

`<inflation layer>.inflation_radius`

Type: double Default: 0.55: Radius to inflate costmap around lethal obstacles.

`<inflation layer>.custom_inscribed_radius`

Type: double Default: -1.0: Custom inscribed radius for the robot which overwrites the default footprint-based calculated one. If set to a negative value, the default inscribed radius of the robot is used.

POTENTIAL SAFETY ISSUE!

Make sure you fully understand the consequences of changing the inscribed radius! This can have serious implications on the robot's safety and is not recommended unless specifically needed. This practice is intended only for controllers that are customized explicitly to feed on such data. It is NOT intended for global path planners or setups that depend on the footprint-based inscribed radius!

`<inflation layer>.cost_scaling_factor`

Type: double Default: 10.0: Exponential decay factor across inflation radius.

`<inflation layer>.inflate_unknown`

Type: bool Default: false: Whether to inflate unknown cells as if lethal.

`<inflation layer>.inflate_around_unknown`

Type: bool Default: false: Whether to inflate unknown cells.

`<inflation layer>.num_threads`

Type: int Default: -1: Number of threads to use for inflation computation when OpenMP is enabled. Set to -1 for auto-detection (uses half of available CPU cores), or specify a positive integer for explicit thread count. Ignored if OpenMP support is not available.

Building with OpenMP

OpenMP parallelization is disabled by default. To enable it, pass the ENABLE_OPENMP CMake option when building:

# Build with OpenMP enabled
colcon build --packages-select nav2_costmap_2d --cmake-args -DENABLE_OPENMP=ON

# Build with OpenMP disabled (default)
colcon build --packages-select nav2_costmap_2d --cmake-args -DENABLE_OPENMP=OFF

Performance Benchmarks

Test Configuration: 2000×2000 Grid (4M cells, 50% occupancy, 2m inflation radius)

Robot Hardware: 16 cores × 5000 MHz

Configuration	Time	Throughput	vs Legacy Inflation Layer
OpenMP disabled	48.9 ms	81.8 M cells/s	2.1× faster
OpenMP enabled	9.11 ms	468.9 M cells/s	11.5× faster