- New friction.py: reads WorldCover friction VRT, resamples to match
elevation grid, provides point sampling for validation
- Modified cost.py: accepts optional friction array, multiplies Tobler
time cost by friction multiplier, inf for water/nodata (255/0)
- Modified prototype.py: loads friction layer, passes to cost function,
validates path avoids water cells (friction=255)
Validated on Idaho test bbox:
- Path avoids Murtaugh Lake (no water cells on path)
- Friction along path: min=10, max=20, mean=10.2
- Effort increased 3.4% vs Phase O1 due to friction multipliers
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
