Debug the pedestrian navmesh
Paths. scripts/… and references/… below are relative to the
directory holding this SKILL.md. Your working directory is the user's
project, not that directory, so prefix them with its absolute path or the
command is not found.
CARLA does not expose navmesh geometry, but every location from
get_random_location_from_navigation() sits on the walkable mesh. Sampling many
of them validates the navmesh loaded and visualises its coverage — the
check to run after importing a map, or when walkers refuse to move.
Instructions
Progress:
- [ ] Step 1: Check prerequisites (bash scripts/check_env.sh), clear FAILs
- [ ] Step 2: Validate — confirm the navmesh exists and its extent
- [ ] Step 3: (rendered view) Sample + draw to see the walkable area
Commands need CARLA_HOST/CARLA_PORT from scripts/env.sh.
Step 1: Check prerequisites
bash scripts/check_env.sh
Step 2: Validate (works headless)
source scripts/env.sh
python3 scripts/navmesh.py validate --count 500
PASS reports the number of valid points, unique locations, and the walkable span.
FAIL (exit 1) means get_random_location_from_navigation() returned nothing — no
usable navmesh, so pedestrians with a WalkerAIController will not navigate.
Step 3: Visualise (rendered server)
python3 scripts/navmesh.py sample --count 2000 --life 120
Draws the sampled points via world.debug; the dotted region is walkable. Needs a
windowed/packaged server (headless -nullrhi draws nothing — see debug-draw).
Examples
Example 1: after importing a map
User says: "I imported a town — did the pedestrian nav build?"
validate → PASS with a sensible span means yes; FAIL means the nav mesh is
missing and must be rebuilt during import.
Example 2: walkers won't move
User says: "my pedestrians just stand still"
validate. If it FAILs, the navmesh is the cause; if it PASSes, look at the
WalkerAIController wiring (owned by the walker-spawning skill), not the map.
Example 3: see the walkable area
User says: "show me where pedestrians can walk"
sample --count 3000 --life 180 on a rendered server; inspect the point cloud.
Troubleshooting
Problem: validate FAILs on a freshly imported map
Cause: pedestrian navigation was not generated/exported for the map.
Solution: rebuild the map's nav mesh in the import pipeline; then re-validate.
Problem: sample prints a count but nothing is visible
Cause: headless -nullrhi server, or the camera is far from the coverage bounds.
Solution: use a rendered server and move the spectator over the reported bounds.
Problem: very few unique locations
Cause: navmesh is tiny or degenerate (a sliver of walkable area).
Solution: check the source geometry / sidewalks in the imported map.
Outputs
validate: a PASS/FAIL report with coverage bounds and walkable span.sample: a transient point overlay of the walkable area (rendered view).
Detail (navmesh basics, WalkerAIController link, import checklist) in
references/navmesh.md.