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	Default
bool	True

Description

Whether it is enabled.

<inflation layer>.inflation_radius

Type	Default
double	0.55

Description

Radius to inflate costmap around lethal obstacles.

<inflation layer>.custom_inscribed_radius

Type	Default
double	-1.0

Description

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	Default
double	10.0

Description

Exponential decay factor across inflation radius.

<inflation layer>.inflate_unknown

Type	Default
bool	False

Description

Whether to inflate unknown cells as if lethal.

<inflation layer>.inflate_around_unknown

Type	Default
bool	False

Description

Whether to inflate unknown cells.

<inflation layer>.num_threads

Type	Default
int	-1

Description

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