Guard min_observable_height() against unbounded boolean stack (#1317)#1320
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`np.empty((n_steps, H, W), bool)` was sized directly from raster dimensions and the binary-search step count with no memory check. n_steps = ceil(log2(max_height/precision)) + 1, so a caller can drive the stack to ~150 GB on a 50000x50000 raster with extreme parameters. Adds `_available_memory_bytes()` and `_check_memory(n_steps, rows, cols)` helpers (1 byte/cell for bool, 50% threshold) and calls the guard after parameter validation but before the np.empty allocation. Same asymmetric guard pattern used in sky_view_factor (#1300), sieve (#1296), kde (#1287), resample (#1295), focal (#1284), geodesic (#1283), mahalanobis (#1288), true_color (#1291), diffuse (#1267), erode (#1275), emerging_hotspots (#1274), dasymetric (#1261). Tests cover oversize-stack rejection, error-message dimensions, normal sizing with ample memory, and that ValueError validation still runs before the memory guard.
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Summary
_available_memory_bytes()and_check_memory(n_steps, rows, cols)tomin_observable_height()(1 byte/cell for the bool stack, 50% threshold).np.empty((n_steps, H, W), bool).experimentalin.claude/sweep-security-state.csv(separate commit on main).Fixes #1317.
Background
The visibility stack at line 122 was sized directly from
raster.shapeandn_steps = ceil(log2(max_height / precision)) + 1. Default args producen_steps = 8, but a caller can drive it much higher:max_height=1e9, precision=1e-9givesn_steps = 60. On a 50000x50000 raster that is ~150 GB of bool stack before anything errors.Same asymmetric guard pattern used in sky_view_factor (#1300), sieve (#1296), kde (#1287), resample (#1295), focal (#1284), geodesic (#1283), mahalanobis (#1288), true_color (#1291), diffuse (#1267), erode (#1275), emerging_hotspots (#1274), dasymetric (#1261).
Test plan
pytest xrspatial/tests/test_min_observable_height.py-- 15 passed (4 new memory-guard cases, 11 existing)MemoryErrorwith a clear messagemax_heightraisesValueErrorbefore the memory guard runs