gdalwarp/gdal raster reproject: add a RESET_DEST_PIXELS=YES/NO warping option to reset the existing output dataset completely to dstnodata/0

Author: rouault

alg/gdalwarper.cpp

@@ -1081,8 +1081,14 @@ const char *GDALWarpGetOptionList(void)
            "Numeric value or NO_DATA. This option forces the destination image "
            "to be initialized to the indicated value (for all bands) "
            "or indicates that it should be initialized to the NO_DATA value in "
-           "padfDstNoDataReal/padfDstNoDataImag. If this value is not set the "
+           "padfDstNoDataReal/padfDstNoDataImag. If this value is not set, the "
            "destination image will be read and overlaid.'/>"
+           "<Option name='RESET_DEST_PIXELS' type='boolean' description='"
+           "Whether the whole destination image must be re-initialized to the "
+           "destination nodata value of padfDstNoDataReal/padfDstNoDataImag "
+           "if set, or 0 otherwise. The main difference with INIT_DEST is that "
+           "it also affects regions not related to the source dataset.' "
+           "default='NO'/>"
            "<Option name='WRITE_FLUSH' type='boolean' description='"
            "This option forces a flush to disk of data after "
            "each chunk is processed. In some cases this helps ensure a serial "
@@ -1292,6 +1298,14 @@ const char *GDALWarpGetOptionList(void)
  * padfDstNoDataReal/padfDstNoDataImag. If this value isn't set the
  * destination image will be read and overlaid.</li>
  *
+ * <li>RESET_DEST_PIXELS=YES/NO (since GDAL 3.13): Defaults to NO.
+ * Whether the whole destination image must be re-initialized to the
+ * destination nodata value of padfDstNoDataReal/padfDstNoDataImag if set,
+ * or 0 otherwise.
+ * The main difference with INIT_DEST is that it also affects regions
+ * not related to the source dataset.
+ * </li>
+ *
  * <li>WRITE_FLUSH=YES/NO: This option forces a flush to disk of data after
  * each chunk is processed. In some cases this helps ensure a serial
  * writing of the output data otherwise a block of data may be written to disk

alg/gdalwarpoperation.cpp

@@ -723,6 +723,21 @@ GDALWarpOperation::Initialize(const GDALWarpOptions *psNewOptions,
         }
     }
 
+    if (eErr == CE_None && psOptions->hDstDS &&
+        CPLTestBool(CSLFetchNameValueDef(psOptions->papszWarpOptions,
+                                         "RESET_DEST_PIXELS", "NO")))
+    {
+        for (int i = 0; eErr == CE_None && i < psOptions->nBandCount; ++i)
+        {
+            eErr = GDALFillRaster(
+                GDALGetRasterBand(psOptions->hDstDS, psOptions->panDstBands[i]),
+                psOptions->padfDstNoDataReal ? psOptions->padfDstNoDataReal[i]
+                                             : 0.0,
+                psOptions->padfDstNoDataImag ? psOptions->padfDstNoDataImag[i]
+                                             : 0.0);
+        }
+    }
+
     return eErr;
 }
 

apps/gdalwarp_lib.cpp

@@ -2792,6 +2792,10 @@ GDALWarpDirect(const char *pszDest, GDALDatasetH hDstDS, int nSrcCount,
             }
         }
 
+        if (iSrc > 0)
+            psOptions->aosWarpOptions.SetNameValue("RESET_DEST_PIXELS",
+                                                   nullptr);
+
         /* --------------------------------------------------------------------
          */
         /*      Create a transformation object from the source to */

autotest/utilities/test_gdalwarp_lib.py

@@ -4771,3 +4771,30 @@ def test_gdalwarp_lib_mask_band_and_src_nodata():
     ):
         out_ds = gdal.Warp("", src_ds, options="-f MEM -dstnodata 5")
         assert out_ds.GetRasterBand(1).ReadRaster() == b"\x05"
+
+
+###############################################################################
+# Test RESET_DEST_PIXELS warping option
+
+
+def test_gdalwarp_lib_RESET_DEST_PIXELS():
+
+    src_ds = gdal.GetDriverByName("MEM").Create("", 3, 3)
+    src_ds.SetGeoTransform([0, 1, 0, 0, 0, -1])
+    src_ds.GetRasterBand(1).Fill(1)
+
+    out_ds = gdal.Warp("", src_ds, format="MEM", dstNodata=0)
+
+    assert out_ds.ReadRaster() == b"\x01" * (3 * 3)
+
+    src_ds = gdal.GetDriverByName("MEM").Create("", 1, 1)
+    src_ds.SetGeoTransform([1, 1, 0, -1, 0, -1])
+    src_ds.GetRasterBand(1).Fill(2)
+
+    src2_ds = gdal.GetDriverByName("MEM").Create("", 1, 1)
+    src2_ds.SetGeoTransform([2, 1, 0, -1, 0, -1])
+    src2_ds.GetRasterBand(1).Fill(3)
+
+    gdal.Warp(out_ds, [src_ds, src2_ds], warpOptions={"RESET_DEST_PIXELS": "YES"})
+
+    assert out_ds.ReadRaster() == b"\x00\x00\x00\x00\x02\x03\x00\x00\x00"