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Auto-retry IGN tiles at lower zoom on 404

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When zoom 20 tiles are unavailable (rural areas), fall back to zoom 19, 18,
etc. down to 15. Breaks out immediately on first-tile 404 to avoid wasting
requests at unsupported zoom levels.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Jacquin Antoine
2026-05-14 02:21:47 +02:00
parent e2bd6b2536
commit f988ddb76d
1 changed files with 80 additions and 54 deletions
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50
lidar_pipeline/ign.py
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@ -76,6 +76,8 @@ def _lat_lon_to_px(lat, lon, zoom, tile_size=256):
def download_ign_tiles(min_x, max_x, min_y, max_y, layer, zoom_level=15):
"""Download IGN WMTS tiles for the given bounds using Web Mercator (PM).
If the first tile returns 404, automatically retries at lower zoom levels.
Args:
min_x, max_x, min_y, max_y: Bounds in Lambert 93.
layer: IGN WMTS layer name.
@ -106,25 +108,32 @@ def download_ign_tiles(min_x, max_x, min_y, max_y, layer, zoom_level=15):
tile_matrix_set = "PM"
tile_size = 256
col_min, row_min = _lat_lon_to_tile(nw_lat, nw_lon, zoom_level)
col_max, row_max = _lat_lon_to_tile(se_lat, se_lon, zoom_level)
# Try downloading at the requested zoom level; fall back to lower zooms on 404
min_zoom = 15
for zoom in range(zoom_level, min_zoom - 1, -1):
col_min, row_min = _lat_lon_to_tile(nw_lat, nw_lon, zoom)
col_max, row_max = _lat_lon_to_tile(se_lat, se_lon, zoom)
nw_px_x, nw_px_y = _lat_lon_to_px(nw_lat, nw_lon, zoom_level)
se_px_x, se_px_y = _lat_lon_to_px(se_lat, se_lon, zoom_level)
nw_px_x, nw_px_y = _lat_lon_to_px(nw_lat, nw_lon, zoom)
se_px_x, se_px_y = _lat_lon_to_px(se_lat, se_lon, zoom)
out_width = int(se_px_x - nw_px_x)
out_height = int(se_px_y - nw_px_y)
if out_width <= 0 or out_height <= 0 or out_width > 10000 or out_height > 10000:
logger.warning(f" Image IGN trop grande: {out_width}x{out_height}px — abandon")
return None
logger.warning(f" Image IGN trop grande: {out_width}x{out_height}px — zoom {zoom} abandon")
continue
total_tiles = (col_max - col_min + 1) * (row_max - row_min + 1)
logger.info(f" Zoom {zoom_level}: {total_tiles} tuiles à télécharger ({out_width}x{out_height}px)")
if zoom < zoom_level:
logger.info(f" ↓ Retry zoom {zoom_level}→{zoom}: {total_tiles} tuiles ({out_width}x{out_height}px)")
else:
logger.info(f" Zoom {zoom}: {total_tiles} tuiles à télécharger ({out_width}x{out_height}px)")
composite = np.full((out_height, out_width, 3), 255, dtype=np.uint8)
tiles_downloaded = 0
tiles_404 = 0
fmt = "image/png" if 'PLAN' in layer else "image/jpeg"
for col in range(col_min, col_max + 1):
@ -133,7 +142,7 @@ def download_ign_tiles(min_x, max_x, min_y, max_y, layer, zoom_level=15):
f"{wmts_url}?SERVICE=WMTS&VERSION=1.0.0&REQUEST=GetTile"
f"&LAYER={layer}&STYLE=normal"
f"&TILEMATRIXSET={tile_matrix_set}"
f"&TILEMATRIX={zoom_level}&TILECOL={col}&TILEROW={row}"
f"&TILEMATRIX={zoom}&TILECOL={col}&TILEROW={row}"
f"&FORMAT={fmt}"
)
@ -167,16 +176,33 @@ def download_ign_tiles(min_x, max_x, min_y, max_y, layer, zoom_level=15):
tile_arr[src_y:src_y+src_h, src_x:src_x+src_w]
tiles_downloaded += 1
except Exception as e:
if tiles_downloaded == 0 and col == col_min and row == row_min:
logger.error(f" ✗ Erreur tuile IGN: {e}")
except urllib.error.HTTPError as e:
if e.code == 404:
tiles_404 += 1
# If the very first tile is 404, this zoom level is unavailable
if col == col_min and row == row_min:
logger.info(f" Zoom {zoom} non disponible (404) — essai zoom inférieur")
break
continue
except Exception:
continue
else:
continue
# Only reach here if inner loop broke (first tile 404)
break
if tiles_404 > 0 and tiles_downloaded == 0:
# No tiles at this zoom, try lower
continue
logger.info(f" → {tiles_downloaded} tuiles IGN téléchargées ({layer})")
if tiles_downloaded == 0:
return None
continue
return composite
logger.error(" ✗ Aucun zoom disponible pour cette zone")
return None
def generate_ign_overlay(dem_file, basename, vis_dir, resolution, layer, title, legend_label, description, out_suffix):
"""Generate an IGN basemap overlay visualization.