Merge pull request #11475 from rouault/vat_dbf

Tiff: add support to read RAT stored in ArcGIS style .tif.vat.dbf auxiliary file

autotest/gcore/tiff_read.py

@@ -5361,3 +5361,108 @@ def test_tiff_read_ovr_dimap_pleiades(tmp_path):
     ds = None
     # Check that cleaning overviews did not suppress the DIMAP XML file
     assert os.path.exists(tmp_path / "bundle" / "DIM_foo.XML")
+
+
+###############################################################################
+# Test reading ArcGIS .tif.vat.dbf auxiliary file
+
+
+@pytest.mark.parametrize("GDAL_DISABLE_READDIR_ON_OPEN", ["NO", "YES", "EMPTY_DIR"])
+def test_tiff_read_vat_dbf(GDAL_DISABLE_READDIR_ON_OPEN):
+
+    with gdal.config_option(
+        "GDAL_DISABLE_READDIR_ON_OPEN", GDAL_DISABLE_READDIR_ON_OPEN
+    ):
+        with gdal.Open("data/gtiff/testrat.tif") as ds:
+            band = ds.GetRasterBand(1)
+            rat = band.GetDefaultRAT()
+
+            if GDAL_DISABLE_READDIR_ON_OPEN == "EMPTY_DIR":
+                assert rat is None
+                return
+
+            assert rat
+            assert rat.GetColumnCount() == 9
+            assert rat.GetRowCount() == 2
+            assert [rat.GetNameOfCol(i) for i in range(9)] == [
+                "VALUE",
+                "COUNT",
+                "CLASS",
+                "Red",
+                "Green",
+                "Blue",
+                "OtherInt",
+                "OtherReal",
+                "OtherStr",
+            ]
+            assert [rat.GetUsageOfCol(i) for i in range(9)] == [
+                gdal.GFU_MinMax,
+                gdal.GFU_PixelCount,
+                gdal.GFU_Name,
+                gdal.GFU_Red,
+                gdal.GFU_Green,
+                gdal.GFU_Blue,
+                gdal.GFU_Generic,
+                gdal.GFU_Generic,
+                gdal.GFU_Generic,
+            ]
+            assert [rat.GetTypeOfCol(i) for i in range(9)] == [
+                gdal.GFT_Integer,
+                gdal.GFT_Integer,
+                gdal.GFT_String,
+                gdal.GFT_Integer,
+                gdal.GFT_Integer,
+                gdal.GFT_Integer,
+                gdal.GFT_Integer,
+                gdal.GFT_Real,
+                gdal.GFT_String,
+            ]
+            assert rat.GetValueAsInt(0, 0) == 1
+            assert rat.GetValueAsInt(0, 1) == 10
+            assert rat.GetValueAsString(0, 2) == "my class"
+            assert rat.GetValueAsInt(0, 3) == 26
+            assert rat.GetValueAsInt(0, 4) == 51
+            assert rat.GetValueAsInt(0, 5) == 128
+            assert rat.GetValueAsInt(0, 6) == 2
+            assert rat.GetValueAsDouble(0, 7) == 2.5
+            assert rat.GetValueAsString(0, 8) == "foo"
+
+            assert rat.GetValueAsInt(1, 0) == 2
+            assert rat.GetValueAsString(1, 2) == "my class2"
+            assert rat.GetValueAsString(1, 8) == "foo2"
+
+            rat = band.GetDefaultRAT()
+            assert rat
+            assert rat.GetColumnCount() == 9
+
+
+###############################################################################
+# Test reading absent ArcGIS .tif.vat.dbf auxiliary file
+
+
+@pytest.mark.parametrize("GDAL_DISABLE_READDIR_ON_OPEN", ["NO", "YES", "EMPTY_DIR"])
+def test_tiff_read_no_vat_dbf(GDAL_DISABLE_READDIR_ON_OPEN):
+
+    with gdal.config_option(
+        "GDAL_DISABLE_READDIR_ON_OPEN", GDAL_DISABLE_READDIR_ON_OPEN
+    ):
+        with gdal.Open("data/byte.tif") as ds:
+            band = ds.GetRasterBand(1)
+            assert band.GetDefaultRAT() is None
+
+
+###############################################################################
+# Test reading corrupted ArcGIS .tif.vat.dbf auxiliary file
+
+
+def test_tiff_read_corrupted_vat_dbf(tmp_vsimem):
+
+    filename = str(tmp_vsimem / "test.tif")
+    gdal.GetDriverByName("GTiff").Create(filename, 1, 1)
+    vat_dbf_filename = filename + ".vat.dbf"
+    gdal.FileFromMemBuffer(vat_dbf_filename, "")
+
+    with gdal.Open(filename) as ds:
+        band = ds.GetRasterBand(1)
+        with pytest.raises(Exception):
+            band.GetDefaultRAT()

doc/source/drivers/raster/gtiff.rst

@@ -246,6 +246,13 @@ GDALGeoTIFF. Note that all bands must use the same nodata value. When
 BASELINE or GeoTIFF profile are used, the nodata value is stored into a
 PAM .aux.xml file.
 
+Raster Attribute Table
+----------------------
+
+Starting with GDAL 3.11, Raster attribute tables stored in auxiliary
+.tif.vat.dbf files, as written by ArcGIS, can be read as GDAL Raster Attribute
+Table.
+
 Sparse files
 ------------
 
@@ -487,7 +494,7 @@ This driver supports the following creation options:
       * ``JXL`` is for JPEG-XL, and is only available when using internal libtiff and building GDAL against
         https://github.com/libjxl/libjxl . It is recommended to use JXL compression with the ``TILED=YES`` creation
         option and block size of 256x256, 512x512, or 1024x1024 pixels. Supported data types are ``Byte``,
-        ``UInt16`` and ``Float32`` only. For GDAL < 3.6.0, JXL compression may only be used alongside 
+        ``UInt16`` and ``Float32`` only. For GDAL < 3.6.0, JXL compression may only be used alongside
         ``INTERLEAVE=PIXEL`` (the default) on datasets with 4 bands or less.
 
       * ``NONE`` is the default.

frmts/gtiff/gtiffrasterband.h

@@ -15,6 +15,7 @@
 #define GTIFFRASTERBAND_H_INCLUDED
 
 #include "gdal_pam.h"
+#include "gdal_rat.h"
 
 #include "gtiff.h"
 
@@ -41,6 +42,7 @@ class GTiffRasterBand CPL_NON_FINAL : public GDALPamRasterBand
     GDALColorInterp m_eBandInterp = GCI_Undefined;
     std::set<GTiffRasterBand **> m_aSetPSelf{};
     bool m_bHaveOffsetScale = false;
+    std::unique_ptr<GDALRasterAttributeTable> m_poRAT{};
 
     int DirectIO(GDALRWFlag eRWFlag, int nXOff, int nYOff, int nXSize,
                  int nYSize, void *pData, int nBufXSize, int nBufYSize,

frmts/gtiff/gtiffrasterband_read.cpp

@@ -34,8 +34,39 @@
 GDALRasterAttributeTable *GTiffRasterBand::GetDefaultRAT()
 
 {
+    if (m_poRAT)
+        return m_poRAT.get();
+
     m_poGDS->LoadGeoreferencingAndPamIfNeeded();
-    return GDALPamRasterBand::GetDefaultRAT();
+    auto poRAT = GDALPamRasterBand::GetDefaultRAT();
+    if (poRAT)
+        return poRAT;
+
+    if (!GDALCanFileAcceptSidecarFile(m_poGDS->m_pszFilename))
+        return nullptr;
+    const std::string osVATDBF =
+        std::string(m_poGDS->m_pszFilename) + ".vat.dbf";
+    CSLConstList papszSiblingFiles = m_poGDS->GetSiblingFiles();
+    if (papszSiblingFiles &&
+        // cppcheck-suppress knownConditionTrueFalse
+        GDALCanReliablyUseSiblingFileList(osVATDBF.c_str()))
+    {
+        int iSibling =
+            CSLFindString(papszSiblingFiles, CPLGetFilename(osVATDBF.c_str()));
+        if (iSibling >= 0)
+        {
+            CPLString osFilename = m_poGDS->m_pszFilename;
+            osFilename.resize(strlen(m_poGDS->m_pszFilename) -
+                              strlen(CPLGetFilename(m_poGDS->m_pszFilename)));
+            osFilename += papszSiblingFiles[iSibling];
+            m_poRAT = GDALLoadVATDBF(osFilename.c_str());
+        }
+        return m_poRAT.get();
+    }
+    VSIStatBufL sStatBuf;
+    if (VSIStatL(osVATDBF.c_str(), &sStatBuf) == 0)
+        m_poRAT = GDALLoadVATDBF(osVATDBF.c_str());
+    return m_poRAT.get();
 }
 
 /************************************************************************/

gcore/CMakeLists.txt

@@ -17,6 +17,7 @@ add_library(
   gdaljp2box.cpp
   gdalmultidomainmetadata.cpp
   gdal_rat.cpp
+  gdal_rat_vat_dbf.cpp
   gdalpamproxydb.cpp
   gdalallvalidmaskband.cpp
   gdalnodatamaskband.cpp

gcore/gdal_rat.cpp

@@ -648,11 +648,57 @@ CPLXMLNode *GDALRasterAttributeTable::Serialize() const
 
         snprintf(szValue, sizeof(szValue), "%d",
                  static_cast<int>(GetTypeOfCol(iCol)));
-        CPLCreateXMLElementAndValue(psCol, "Type", szValue);
+        CPLXMLNode *psType =
+            CPLCreateXMLElementAndValue(psCol, "Type", szValue);
+        const char *pszTypeStr = "String";
+        switch (GetTypeOfCol(iCol))
+        {
+            case GFT_Integer:
+                pszTypeStr = "Integer";
+                break;
+            case GFT_Real:
+                pszTypeStr = "Real";
+                break;
+            case GFT_String:
+                break;
+        }
+        CPLAddXMLAttributeAndValue(psType, "typeAsString", pszTypeStr);
 
         snprintf(szValue, sizeof(szValue), "%d",
                  static_cast<int>(GetUsageOfCol(iCol)));
-        CPLCreateXMLElementAndValue(psCol, "Usage", szValue);
+        CPLXMLNode *psUsage =
+            CPLCreateXMLElementAndValue(psCol, "Usage", szValue);
+        const char *pszUsageStr = "";
+
+#define USAGE_STR(x)                                                           \
+    case GFU_##x:                                                              \
+        pszUsageStr = #x;                                                      \
+        break
+        switch (GetUsageOfCol(iCol))
+        {
+            USAGE_STR(Generic);
+            USAGE_STR(PixelCount);
+            USAGE_STR(Name);
+            USAGE_STR(Min);
+            USAGE_STR(Max);
+            USAGE_STR(MinMax);
+            USAGE_STR(Red);
+            USAGE_STR(Green);
+            USAGE_STR(Blue);
+            USAGE_STR(Alpha);
+            USAGE_STR(RedMin);
+            USAGE_STR(GreenMin);
+            USAGE_STR(BlueMin);
+            USAGE_STR(AlphaMin);
+            USAGE_STR(RedMax);
+            USAGE_STR(GreenMax);
+            USAGE_STR(BlueMax);
+            USAGE_STR(AlphaMax);
+            case GFU_MaxCount:
+                break;
+        }
+#undef USAGE_STR
+        CPLAddXMLAttributeAndValue(psUsage, "usageAsString", pszUsageStr);
     }
 
     /* -------------------------------------------------------------------- */

gcore/gdal_rat.h

@@ -386,4 +386,7 @@ class CPL_DLL GDALDefaultRasterAttributeTable : public GDALRasterAttributeTable
     void RemoveStatistics() override;
 };
 
+std::unique_ptr<GDALRasterAttributeTable>
+    CPL_DLL GDALLoadVATDBF(const char *pszFilename);
+
 #endif /* ndef GDAL_RAT_H_INCLUDED */