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>.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