diff --git a/.gitignore b/.gitignore
index d73015725..6eb303fc2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,3 @@
-```
 # Compiled and build artifacts
 *.pyc
 __pycache__/
@@ -68,4 +67,6 @@ htmlcov/
 *.tar.bz2
 *.tar.xz
 *.tar.zst
-```
\ No newline at end of file
+
+# Rust backup files
+**/*.rs.bk
diff --git a/src/elevation/providers/copernicus.rs b/src/elevation/providers/copernicus.rs
index edb35fffb..1de210ea9 100644
--- a/src/elevation/providers/copernicus.rs
+++ b/src/elevation/providers/copernicus.rs
@@ -42,9 +42,9 @@ impl ElevationProvider for CopernicusDem30 {
         grid_height: usize,
     ) -> Result<RawElevationGrid, Box<dyn std::error::Error>> {
         use reqwest::blocking::Client;
-        use std::time::Duration;
-        use tiff::decoder::Decoder;
         use std::io::Cursor;
+        use std::time::Duration;
+        use tiff::decoder::{Decoder, DecodingResult};
 
         let client = Client::builder()
             .timeout(Duration::from_secs(120))
@@ -145,12 +145,18 @@ impl ElevationProvider for CopernicusDem30 {
             let height = decoder.dimensions()?.1 as usize;
             tile_dims.insert((lat, lng), (width, height));
 
-            // Read the image data - Copernicus DEM uses 32-bit float
-            let mut buf = vec![0.0f32; width * height];
-            decoder.read_f32_into(&mut buf)?;
-
-            // Convert to f64 and store
-            let heights: Vec<f64> = buf.into_iter().map(|v| v as f64).collect();
+            // Read the image data - Copernicus DEM uses 32-bit float.
+            let heights: Vec<f64> = match decoder.read_image()? {
+                DecodingResult::F32(values) => values.into_iter().map(f64::from).collect(),
+                DecodingResult::F64(values) => values,
+                other => {
+                    return Err(format!(
+                        "Unsupported Copernicus DEM sample format: {:?}",
+                        other
+                    )
+                    .into());
+                }
+            };
             tile_data.insert((lat, lng), heights);
         }
 
diff --git a/src/overture.rs b/src/overture.rs
index 6e5ddbb2a..7ac73e56a 100644
--- a/src/overture.rs
+++ b/src/overture.rs
@@ -390,6 +390,7 @@ fn overlaps_with_grid(
     bboxes: &[(i32, i32, i32, i32)],
     grid_min_x: i32,
     grid_min_z: i32,
+    cell_size: i32,
 ) -> bool {
     if way.nodes.is_empty() {
         return false;
@@ -1122,6 +1123,13 @@ fn parse_row_group_by_collection<R: ChunkReader + 'static>(
 ) -> Result<Vec<ProcessedElement>, Box<dyn std::error::Error>> {
     let row_group_reader = reader.get_row_group(rg_idx)?;
     let row_iter = row_group_reader.get_row_iter(None)?;
+    let bbox = LLBBox::new(
+        target_min_lat,
+        target_min_lng,
+        target_max_lat,
+        target_max_lng,
+    )
+    .map_err(|err| std::io::Error::new(std::io::ErrorKind::InvalidInput, err))?;
 
     match collection {
         OvertureCollection::Building => {
@@ -1145,7 +1153,8 @@ fn parse_row_group_by_collection<R: ChunkReader + 'static>(
                     if b.is_osm_sourced {
                         return None;
                     }
-                    building_to_processed_way(&b, coord_transformer, &LLBBox::new_unchecked(target_min_lat, target_min_lng, target_max_lat, target_max_lng))
+                    building_to_processed_way(&b, coord_transformer, &bbox)
+                        .map(ProcessedElement::Way)
                 })
                 .collect())
         }
@@ -1170,7 +1179,8 @@ fn parse_row_group_by_collection<R: ChunkReader + 'static>(
                     if r.is_osm_sourced {
                         return None;
                     }
-                    road_to_processed_way(&r, coord_transformer, &LLBBox::new_unchecked(target_min_lat, target_min_lng, target_max_lat, target_max_lng))
+                    road_to_processed_way(&r, coord_transformer, &bbox)
+                        .map(ProcessedElement::Way)
                 })
                 .collect())
         }
@@ -1195,7 +1205,8 @@ fn parse_row_group_by_collection<R: ChunkReader + 'static>(
                     if w.is_osm_sourced {
                         return None;
                     }
-                    water_to_processed_way(&w, coord_transformer, &LLBBox::new_unchecked(target_min_lat, target_min_lng, target_max_lat, target_max_lng))
+                    water_to_processed_way(&w, coord_transformer, &bbox)
+                        .map(ProcessedElement::Way)
                 })
                 .collect())
         }
@@ -1220,7 +1231,8 @@ fn parse_row_group_by_collection<R: ChunkReader + 'static>(
                     if l.is_osm_sourced {
                         return None;
                     }
-                    landuse_to_processed_way(&l, coord_transformer, &LLBBox::new_unchecked(target_min_lat, target_min_lng, target_max_lat, target_max_lng))
+                    landuse_to_processed_way(&l, coord_transformer, &bbox)
+                        .map(ProcessedElement::Way)
                 })
                 .collect())
         }