nx_geo_los.nx

nx_geo_los.nx -- LIB: GEO-022 LINE-OF-SIGHT / viewshed over a terrain elevation profile (DEM). Given an elevation profile sampled along a transect (heights[0..n]), an observer at index 0 and a target at index n (each with an eye/structure height above ground), the target is VISIBLE iff no intermediate terrain sample rises above the straight sight-line from observer to target. THE EXCEED ANGLE: the sight-line test is INTEGER and cross-multiplied -- compare heights[i]*n against obsH*n + (tgtH-obsH)*i (no division, no float) -> the visible/blocked verdict is EXACT and deterministic, even when a terrain sample sits exactly on the sight-line (decided, not an epsilon coin-flip). Sovereign + offline; the DEM is seeded data, not a service. license_tier: ORIGINAL