The method · approach-1 · formula 1
A route is useful only if you can explain why it goes there.
Approach is an on-foot, time-dependent A* router over an audited road and trail graph. When off-trail travel is enabled, the current online planner can add a direct evidence-checked connector from a selected pin to that graph. It is available only after a state graph passes the access-intersection audit. The current release set is CO, WY, CA, AZ, MT, PA, UT, ID, NV, NM, OR, WA, NY, ND, ME, and AK.
Access fails closed
Known public and verified walk-in land can route. Private, closed, and unknown access cannot. Off-network connectors must remain on PAD-US open public land, stay below the selected maximum slope using sampled 3DEP elevation, and avoid mapped NHD water areas. A permission corridor can authorize the connector only inside that saved personal or Trip plan; it is never promoted into shared map data. The current connector is direct and does not search for an off-trail detour, so a legal route may still return “no route found” when the straight connector fails.
The cost we minimize
Each edge combines estimated hiking minutes, positive elevation gain, slope, trail and surface preference, path smoothness, off-trail distance, and protected-area scent exposure. Balanced uses weights 1.0, 1.5, 7.0, 0.25, and 0.2 respectively after the published unit normalization. Fastest, Lowest scent, and Least climbing change those weights; hard access constraints never change.
Scent is geometry, not walking direction
At the estimated time each segment is traversed, the ambient and terrain-driven thermal winds are combined as vectors. A widening scent cone is projected from that segment. Exposure is counted only when the projected cone intersects the hunter-confirmed protected Polygon or MultiPolygon. Entry is solved backward from arrival; exit is solved forward from departure.
Variants and uncertainty
The router asks for four presets, then removes pairs sharing at least 85% of their edges. Every surviving pair reports distance, ETA, gain, off-trail distance, protected-area exposure, uncertainty, engine version, and source vintages. Trips outside forecast range keep legal and terrain routing but mark scent pending; Watch may later propose a refreshed candidate, never silently replace the primary.
Limits
Approach is decision support, not a guarantee of legal access, wind, safety, or animal behavior. Forecast weather expires independently from route legality. It does not support vehicles, spoken navigation, automatic rerouting, new offline route generation, wildlife prediction, or generated hunting spots. When the evidence cannot support a route, the result is “no route found.”