[pull] master from OSGeo:master

alg/contour.cpp

@@ -141,8 +141,11 @@ struct PolygonContourWriter
             currentGeometry_->addGeometryDirectly(currentPart_);
         }
 
-        OGRPolygonContourWriter(previousLevel_, currentLevel_,
-                                *currentGeometry_, poInfo_);
+        if (currentGeometry_->getNumGeometries() > 0)
+        {
+            OGRPolygonContourWriter(previousLevel_, currentLevel_,
+                                    *currentGeometry_, poInfo_);
+        }
 
         currentGeometry_.reset(nullptr);
         currentPart_ = nullptr;
@@ -514,7 +517,9 @@ an averaged value from the two nearby points (in this case (12+3+5)/3).
  *   FIXED_LEVELS=f[,f]*
  *
  * The list of fixed contour levels at which contours should be generated.
- * This option has precedence on LEVEL_INTERVAL
+ * This option has precedence on LEVEL_INTERVAL. MIN and MAX can be used
+ * as special values to represent the minimum and maximum values of the
+ * raster.
  *
  *   NODATA=f
  *
@@ -607,7 +612,19 @@ CPLErr GDALContourGenerateEx(GDALRasterBandH hBand, void *hLayer,
         fixedLevels.resize(aosLevels.size());
         for (size_t i = 0; i < fixedLevels.size(); i++)
         {
-            fixedLevels[i] = CPLAtof(aosLevels[i]);
+            // Handle min/max values
+            if (EQUAL(aosLevels[i], "MIN"))
+            {
+                fixedLevels[i] = std::numeric_limits<double>::lowest();
+            }
+            else if (EQUAL(aosLevels[i], "MAX"))
+            {
+                fixedLevels[i] = std::numeric_limits<double>::max();
+            }
+            else
+            {
+                fixedLevels[i] = CPLAtof(aosLevels[i]);
+            }
             if (i > 0 && !(fixedLevels[i] >= fixedLevels[i - 1]))
             {
                 CPLError(CE_Failure, CPLE_AppDefined,
@@ -712,13 +729,27 @@ CPLErr GDALContourGenerateEx(GDALRasterBandH hBand, void *hLayer,
 
     bool ok = true;
 
+    // Replace fixed levels min/max values with raster min/max values
+    if (!fixedLevels.empty())
+    {
+        if (fixedLevels[0] == std::numeric_limits<double>::lowest())
+        {
+            fixedLevels[0] = dfMinimum;
+        }
+        if (fixedLevels.back() == std::numeric_limits<double>::max())
+        {
+            fixedLevels.back() = dfMaximum;
+        }
+    }
+
     try
     {
         if (polygonize)
         {
 
             if (!fixedLevels.empty())
             {
+
                 // If the minimum raster value is larger than the first requested
                 // level, select the requested level that is just below the
                 // minimum raster value
@@ -781,6 +812,8 @@ CPLErr GDALContourGenerateEx(GDALRasterBandH hBand, void *hLayer,
                 }
                 // Append minimum value to fixed levels
                 fixedLevels.push_back(dfMinimum);
+                // Append maximum value to fixed levels
+                fixedLevels.push_back(dfMaximum);
             }
             else if (contourInterval != 0)
             {
@@ -798,6 +831,8 @@ CPLErr GDALContourGenerateEx(GDALRasterBandH hBand, void *hLayer,
                 }
                 // Append minimum value to fixed levels
                 fixedLevels.push_back(dfMinimum);
+                // Append maximum value to fixed levels
+                fixedLevels.push_back(dfMaximum);
             }
 
             if (!fixedLevels.empty())
@@ -814,6 +849,11 @@ CPLErr GDALContourGenerateEx(GDALRasterBandH hBand, void *hLayer,
                     -std::numeric_limits<double>::infinity(), dfMaximum);
                 SegmentMerger<RingAppender, FixedLevelRangeIterator> writer(
                     appender, levels, /* polygonize */ true);
+                std::vector<int> aoiSkipLevels;
+                // Skip first and last levels (min/max) in polygonal case
+                aoiSkipLevels.push_back(0);
+                aoiSkipLevels.push_back(static_cast<int>(levels.levelsCount()));
+                writer.setSkipLevels(aoiSkipLevels);
                 ContourGeneratorFromRaster<decltype(writer),
                                            FixedLevelRangeIterator>
                     cg(hBand, useNoData, noDataValue, writer, levels);

alg/gdalwarper.cpp

@@ -1284,6 +1284,10 @@ CPLErr GDALWarpDstAlphaMasker(void *pMaskFuncArg, int nBandCount,
  * EXCLUDED_VALUES_PCT_THRESHOLD.
  * Only taken into account by Average currently.</li>
  *
+ * <li>MODE_TIES=FIRST/MIN/MAX: (GDAL >= 3.11) Strategy to use when breaking
+ * ties with MODE resampling. By default, the first value encountered will be used.
+ * Alternatively, the minimum or maximum value can be selected.</li>
+ *
  * </ul>
  */
 
@@ -1305,6 +1309,7 @@ GDALWarpOptions *CPL_STDCALL GDALCreateWarpOptions()
     psOptions->eResampleAlg = GRA_NearestNeighbour;
     psOptions->pfnProgress = GDALDummyProgress;
     psOptions->eWorkingDataType = GDT_Unknown;
+    psOptions->eTieStrategy = GWKTS_First;
 
     return psOptions;
 }

alg/gdalwarper.h

@@ -130,6 +130,14 @@ CPLErr CPL_DLL GDALWarpCutlineMaskerEx(void *pMaskFuncArg, int nBandCount,
 
 /*! @endcond */
 
+/*! GWKMode tie-breaking strategy */
+typedef enum
+{
+    /* Choose the first value encountered */ GWKTS_First = 1,
+    /* Choose the minimal value */ GWKTS_Min = 2,
+    /* Choose the maximum value */ GWKTS_Max = 3,
+} GWKTieStrategy;
+
 /************************************************************************/
 /*                           GDALWarpOptions                            */
 /************************************************************************/
@@ -243,6 +251,8 @@ typedef struct
      * zero. */
     double dfCutlineBlendDist;
 
+    /** Tie-breaking method */
+    GWKTieStrategy eTieStrategy;
 } GDALWarpOptions;
 
 GDALWarpOptions CPL_DLL *CPL_STDCALL GDALCreateWarpOptions(void);
@@ -451,6 +461,8 @@ class CPL_DLL GDALWarpKernel
     // Average currently
     std::vector<std::vector<double>> m_aadfExcludedValues{};
 
+    GWKTieStrategy eTieStrategy;
+
     /*! @endcond */
 
     GDALWarpKernel();