From 1d26440acbd952475f86180c1e058fd2600c2dd8 Mon Sep 17 00:00:00 2001
From: "s0wlz (Matthias Puchstein)" <matthias@puchstein.lu>
Date: Sat, 13 Dec 2025 19:18:50 +0100
Subject: [PATCH] Preserve source tile bounds during export

---
 export_heightmaps.py | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/export_heightmaps.py b/export_heightmaps.py
index 9eba2c3..ff11c17 100644
--- a/export_heightmaps.py
+++ b/export_heightmaps.py
@@ -41,12 +41,11 @@ with open(manifest_path, "w", encoding="utf-8") as f:
         gt = tds.GetGeoTransform()
         ulx, xres, _, uly, _, yres = gt  # yres typically negative in north-up rasters
 
-        # Snap tile bounds to the 1000 m grid to avoid drift/seams.
-        # (This also neutralizes the 1001×1001 overlap nuance.)
-        xmin = math.floor(ulx / TILE_SIZE_M) * TILE_SIZE_M
-        ymax = math.ceil(uly / TILE_SIZE_M) * TILE_SIZE_M
-        xmax = xmin + TILE_SIZE_M
-        ymin = ymax - TILE_SIZE_M
+        # Use the source tile footprint directly to avoid shifting during export.
+        xmax = ulx + xres * tds.RasterXSize
+        ymin = uly + yres * tds.RasterYSize
+        xmin = ulx
+        ymax = uly
 
         base = os.path.splitext(os.path.basename(tif))[0]
         tile_id = base  # keep stable naming = easy re-export + reimport