Handle DHMV WCS edge grid rounding

backend/app/services/dhmv_acquisition_service.py

@@ -51,6 +51,8 @@ class DhmvAcquisitionService:
     WCS_REQUEST_INTERVAL_SECONDS = 2.0
     WCS_RETRY_DELAY_SECONDS = 4.0
     WCS_TRANSIENT_STATUS_CODES = frozenset({400, 429, 502, 503, 504})
+    WCS_EDGE_RESOLUTION_REL_TOLERANCE = 0.05
+    WCS_EDGE_RESOLUTION_ABS_TOLERANCE_M = 0.25
     DTM_CATALOG_URL = (
         "https://www.vlaanderen.be/datavindplaats/catalogus/"
         "digitaal-hoogtemodel-vlaanderen-ii-dtm-raster-1-m"
@@ -349,11 +351,14 @@ class DhmvAcquisitionService:
         )
 
     @staticmethod
-    def _mosaic_geotiffs(coverages: list[bytes], expected_resolution_m: float | None = None) -> bytes:
+    def _mosaic_geotiffs(
+        coverages: list[bytes],
+        expected_resolution_m: float | None = None,
+        diagnostics: dict[str, Any] | None = None,
+    ) -> bytes:
         if len(coverages) == 1:
             return coverages[0]
         try:
-            import rasterio
             from rasterio.io import MemoryFile
             from rasterio.merge import merge
         except ImportError as exc:
@@ -370,14 +375,23 @@ class DhmvAcquisitionService:
             target_resolution = float(expected_resolution_m or abs(float(sources[0].res[0])))
             invalid_crs = [index for index, source in enumerate(sources) if source.crs is None or source.crs.to_epsg() != 31370]
             invalid_bands = [index for index, source in enumerate(sources) if source.count != 1]
+            tile_resolutions = [
+                [abs(float(source.res[0])), abs(float(source.res[1]))]
+                for source in sources
+            ]
             invalid_resolution = [
                 {
                     "tile_index": index,
-                    "resolution": [abs(float(source.res[0])), abs(float(source.res[1]))],
+                    "resolution": tile_resolutions[index],
                 }
                 for index, source in enumerate(sources)
                 if not all(
-                    math.isclose(abs(float(value)), target_resolution, rel_tol=0.02, abs_tol=0.05)
+                    math.isclose(
+                        abs(float(value)),
+                        target_resolution,
+                        rel_tol=DhmvAcquisitionService.WCS_EDGE_RESOLUTION_REL_TOLERANCE,
+                        abs_tol=DhmvAcquisitionService.WCS_EDGE_RESOLUTION_ABS_TOLERANCE_M,
+                    )
                     for value in source.res
                 )
             ]
@@ -393,6 +407,23 @@ class DhmvAcquisitionService:
                     },
                     status_code=502,
                 )
+            harmonized_tile_indexes = [
+                index
+                for index, resolution in enumerate(tile_resolutions)
+                if not all(
+                    math.isclose(value, target_resolution, rel_tol=0.02, abs_tol=0.05)
+                    for value in resolution
+                )
+            ]
+            if diagnostics is not None:
+                diagnostics.update(
+                    {
+                        "source_tile_resolutions_m": tile_resolutions,
+                        "target_resolution_m": target_resolution,
+                        "harmonized_tile_indexes": harmonized_tile_indexes,
+                        "harmonization_method": "rasterio_merge_target_resolution" if harmonized_tile_indexes else None,
+                    }
+                )
             mosaic, transform = merge(
                 sources,
                 res=(target_resolution, target_resolution),
@@ -471,19 +502,25 @@ class DhmvAcquisitionService:
             coverage_hash.update(coverage_content)
             content_types.append(content_type)
             coverages.append(coverage_content)
-        return DhmvAcquisitionService._mosaic_geotiffs(coverages, prepared["resolution_m"]), {
+        mosaic_diagnostics: dict[str, Any] = {}
+        mosaic = DhmvAcquisitionService._mosaic_geotiffs(
+            coverages,
+            prepared["resolution_m"],
+            diagnostics=mosaic_diagnostics,
+        )
+        return mosaic, {
             "tile_count": len(request_urls),
             "request_urls": request_urls,
             "response_content_types": content_types,
             "response_sha256": raw_hash.hexdigest(),
             "coverage_sha256": coverage_hash.hexdigest(),
+            "grid_harmonization": mosaic_diagnostics,
         }
 
     @staticmethod
     def _normalize_raster(content: bytes, scope_geometry_4326, prepared: dict[str, Any]) -> tuple[bytes, dict[str, Any]]:
         try:
             import numpy as np
-            import rasterio
             from rasterio.io import MemoryFile
             from rasterio.mask import mask
         except ImportError as exc:
@@ -656,6 +693,7 @@ class DhmvAcquisitionService:
                 "response_content_types": transfer["response_content_types"],
                 "response_sha256": transfer["response_sha256"],
                 "coverage_sha256": transfer["coverage_sha256"],
+                "grid_harmonization": transfer["grid_harmonization"],
                 "normalized_sha256": hashlib.sha256(normalized_content).hexdigest(),
                 "bbox_epsg4326": prepared["bbox_epsg4326"],
                 "bbox_epsg31370": prepared["bbox_epsg31370"],