diff --git a/config/config_system_terrain.py b/config/config_system_terrain.py
index e28ab794b..7f2a8dfde 100644
--- a/config/config_system_terrain.py
+++ b/config/config_system_terrain.py
@@ -100,7 +100,8 @@ SURFACE_MODEL_SYNC_TIMEOUT_SECONDS = int(os.getenv("SURFACE_MODEL_SYNC_TIMEOUT_S
 
 # footprint(외곽) 산출
 SURFACE_FOOTPRINT_RESOLUTION_M = float(os.getenv("SURFACE_FOOTPRINT_RESOLUTION_M", "1.0"))
-SURFACE_FOOTPRINT_GAP_CLOSE_M = float(os.getenv("SURFACE_FOOTPRINT_GAP_CLOSE_M", "1.0"))
+# 외곽 틈 닫기 3 m — DJI 지면점이 성긴 숲 띠까지 스캔 범위로 살림(요구 558).
+SURFACE_FOOTPRINT_GAP_CLOSE_M = float(os.getenv("SURFACE_FOOTPRINT_GAP_CLOSE_M", "3.0"))
 SURFACE_BOUNDARY_INSET_M = float(os.getenv("SURFACE_BOUNDARY_INSET_M", "1.0"))
 SURFACE_KEEP_LARGEST_FOOTPRINT = (
     os.getenv("SURFACE_KEEP_LARGEST_FOOTPRINT", "True").lower() == "true"
diff --git a/resources/tester/test_640_lidar_default.py b/resources/tester/test_640_lidar_default.py
index f92ee1b75..6c2a776ef 100644
--- a/resources/tester/test_640_lidar_default.py
+++ b/resources/tester/test_640_lidar_default.py
@@ -134,3 +134,22 @@ def test_설정_지문이_바뀌면_implicit_다시_지음(tmp_path: Path) -> No
     with np.load(tmp_path / "implicit_a.npz") as new:
         assert len(new["center_z"]) == 2_000
     assert manifest["source_filters"]["a"]["methods"]["implicit"]["center_count"] == 2_000
+
+
+def test_외곽_틈_닫기_3m_는_성긴_띠를_살림() -> None:
+    points = _plane(60.0)
+    gap = (points[:, 0] > 28) & (points[:, 0] < 33)  # 5 m 빈 띠 — 1 m 닫기면 두 덩이
+    points = points[~gap]
+
+    def area(close_m: float) -> float:
+        config = dict(cfg.build_surface_model_config(), footprint_gap_close_meters=close_m)
+        context = TerrainContext(
+            xyz=points,
+            mask=np.ones(len(points), bool),
+            bounds=np.array([points.min(axis=0), points.max(axis=0)]).T,
+            config=config,
+        )
+        return context.footprint_metadata()["footprint_area_m2"]
+
+    assert cfg.SURFACE_FOOTPRINT_GAP_CLOSE_M == 3.0
+    assert area(3.0) > 1.8 * area(1.0)  # 한 덩이(띠 포함) 대 큰 덩이 하나