Make isochrone geotiff serialization use "north up" geotransform (val…

…halla#5019)
ianthetechie · Feb 7, 2025 · 23eed9f · 23eed9f
1 parent bd2f3f9
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Showing 3 changed files with 30 additions and 4 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,6 +8,7 @@
    * FIXED: update CircleCI runners to Ubuntu 24.04 [#5002](https://github.com/valhalla/valhalla/pull/5002)
    * FIXED: Fixed a typo in the (previously undocumented) matrix-APIs responses `algorithm` field: `timedistancbssematrix` is now `timedistancebssmatrix` [#5000](https://github.com/valhalla/valhalla/pull/5000).
    * FIXED: More trivial cases in `CostMatrix` [#5001](https://github.com/valhalla/valhalla/pull/5001)
+   * FIXED: Make isochrone geotiff serialization use "north up" geotransform [#5019](https://github.com/valhalla/valhalla/pull/5019)
 * **Enhancement**
    * ADDED: Consider smoothness in all profiles that use surface [#4949](https://github.com/valhalla/valhalla/pull/4949)
    * ADDED: `admin_crossings` request parameter for `/route` [#4941](https://github.com/valhalla/valhalla/pull/4941)

diff --git a/src/tyr/isochrone_serializer.cc b/src/tyr/isochrone_serializer.cc
@@ -197,10 +197,9 @@ std::string serializeGeoTIFF(Api& request, const std::shared_ptr<const GriddedDa
   double geo_transform[6] = {isogrid->TileBounds(isogrid->TileId(box[0], box[1])).minx(), // minx
                              isogrid->TileSize(),
                              0,
-                             isogrid->TileBounds(isogrid->TileId(box[0], box[1])).miny(), // miny
+                             isogrid->TileBounds(isogrid->TileId(box[0], box[3])).maxy(), // maxy
                              0,
-                             isogrid->TileSize()};
-
+                             -isogrid->TileSize()};
   geotiff_dataset->SetGeoTransform(geo_transform);
   geotiff_dataset->SetSpatialRef(const_cast<OGRSpatialReference*>(&spatial_ref));
 
@@ -214,10 +213,11 @@ std::string serializeGeoTIFF(Api& request, const std::shared_ptr<const GriddedDa
     for (int32_t i = 0; i < ext_y; ++i) {
       for (int32_t j = 0; j < ext_x; ++j) {
         auto tileid = isogrid->TileId(j + box[0], i + box[1]);
-        data[i * ext_x + j] =
+        data[(ext_y - 1 - i) * ext_x + j] =
             static_cast<uint16_t>(isogrid->DataAt(tileid, metric_idx) * scale_factor);
       }
     }
+
     auto band = geotiff_dataset->GetRasterBand(nbands == 2 ? (metric_idx + 1) : 1);
     band->SetNoDataValue(std::numeric_limits<uint16_t>::max());
     band->SetDescription(metric_idx == 0 ? "Time (seconds)" : "Distance (10m)");

diff --git a/test/isochrone.cc b/test/isochrone.cc
@@ -495,6 +495,31 @@ TEST(Isochrones, test_geotiff_output_time_distance) {
   }
   VSIFCloseL(handle);
 }
+TEST(Isochrones, test_geotiff_vertical_orientation) {
+  loki_worker_t loki_worker(cfg);
+  thor_worker_t thor_worker(cfg);
+
+  const auto request =
+      R"({"costing":"auto","locations":[{"lon":5.042799,"lat":52.093199}],"contours":[{"distance":1}], "format": "geotiff"})";
+  Api request_pbf;
+  ParseApi(request, Options::isochrone, request_pbf);
+  loki_worker.isochrones(request_pbf);
+  std::string geotiff = thor_worker.isochrones(request_pbf);
+
+  std::string name = "/vsimem/test_isogrid_geotiff_d.tif";
+  unsigned char buffer[geotiff.length()];
+  std::copy(geotiff.cbegin(), geotiff.cend(), buffer);
+  auto handle = VSIFileFromMemBuffer(name.c_str(), buffer, static_cast<int>(geotiff.size()), 0);
+  auto geotiff_dataset = GDALDataset::FromHandle(GDALOpen(name.c_str(), GA_ReadOnly));
+  int y = geotiff_dataset->GetRasterYSize();
+  double geoTransform[6];
+  geotiff_dataset->GetGeoTransform(geoTransform);
+  double topY = geoTransform[3] + 0 * geoTransform[4] + 0 * geoTransform[5];
+  double bottomY = geoTransform[3] + 0 * geoTransform[4] + y * geoTransform[5];
+  ASSERT_TRUE(topY > bottomY);
+
+  VSIFCloseL(handle);
+}
 #endif
 
 } // namespace