Fix low-terrain startup and extraction placement; record Workshop 0.0.121

docs/terrain-takeover.md

@@ -131,6 +131,22 @@ without resetting that total budget. The fallback surveys the terrain for a
 helicopter landing zone and retains the normal primary/secondary aircraft
 clearance and navigation checks.
 
+Extraction pads do not use the camp-only 12 m road exclusion, and their initial
+ground survey uses the same 0.8 m height variation limit as the landing-zone
+survey. Camp footprints retain their 0.6 m limit and road exclusion. Aircraft
+clearance is tested at the centre's actual terrain height, matching pickup
+registration, rather than the lowest point sampled across the camp grid.
+Water, physical obstacles, guard/patrol ground and navigation, the 28 m landing
+footprint, overhead clearance and additional transport-pad checks still apply.
+
+Dry ground is determined from the terrain's actual water surface, not a fixed
+world-altitude minimum. Site clearance queries water at every sampled terrain
+height instead of testing placeholder candidate heights. Dry terrain below
+one metre (including negative map elevations) can qualify; submerged terrain,
+invalid heights, excessive slopes and physical obstructions remain rejected.
+Site creation, character spawn slots, airfield pads and mortar setup use the
+same terrain-height water check, without the 10 cm character spawn lift.
+
 On terrain-generated maps, prison-to-airport separation is 15% of the shorter
 world axis, clamped to 200–1,500 m (300 m on a 2 km map). This changes tactical
 spacing, not the physical footprint or slope allowance. Original authored Everon