VRT a_nodata for vrt:// connection

OSGeo · Nov 24, 2023 · 66f4425 · 66f4425
1 parent fe649a8
commit 66f4425
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diff --git a/autotest/gcore/vrt_read.py b/autotest/gcore/vrt_read.py
@@ -1604,6 +1604,9 @@ def test_vrt_protocol():
         1e-9,
     )
 
+    ds = gdal.Open("vrt://data/float32.tif?a_nodata=-9999")
+    assert ds.GetRasterBand(1).GetNoDataValue() == -9999.0
+
     ## multiple open options
     ds = gdal.Open(
         "vrt://data/byte_with_ovr.tif?oo=GEOREF_SOURCES=TABFILE,OVERVIEW_LEVEL=0"

diff --git a/doc/source/drivers/raster/vrt.rst b/doc/source/drivers/raster/vrt.rst
@@ -1903,7 +1903,7 @@ For example:
     vrt://my.tif?bands=2&ovr=4
 
 
-The supported options currently are ``bands``, ``a_srs``, ``a_ullr``, ``ovr``, ``expand``,
+The supported options currently are ``bands``, ``a_nodata``, ``a_srs``, ``a_ullr``, ``ovr``, ``expand``,
 ``a_scale``, ``a_offset``, ``ot``, ``gcp``, ``if``, ``scale``, ``exponent``, ``outsize``, ``projwin``,
 ``projwin_srs``, ``tr``, ``r``, ``srcwin``, ``a_gt``, ``oo``, ``unscale``, ``a_coord_epoch``, ``nogcp``, ``epo``, and ``eco``.
 
@@ -1914,6 +1914,9 @@ are the source band numbers (between 1 and N), possibly out-of-order or with rep
 The ``mask`` value can be used to specify the global mask band. This can also
 be seen as an equivalent of running `gdal_translate -of VRT -b num1 ... -b numN`.
 
+The effect of the ``a_nodata`` option (added in GDAL 3.9) is to assign (override) the nodata
+value of the source in the same way as (:ref:`gdal_translate`).
+
 The effect of the ``a_srs`` option (added in GDAL 3.7) is to assign (override) the coordinate
 reference system of the source in the same way as (:ref:`gdal_translate`), it may be missing,
 or incorrect. The value provided for ``a_srs`` may be a string or a file containing a srs

diff --git a/frmts/vrt/vrtdataset.cpp b/frmts/vrt/vrtdataset.cpp
@@ -1088,6 +1088,12 @@ GDALDataset *VRTDataset::OpenVRTProtocol(const char *pszSpec)
                 }
             }
 
+            else if (EQUAL(pszKey, "a_nodata"))
+            {
+                argv.AddString("-a_nodata");
+                argv.AddString(pszValue);
+            }
+
             else if (EQUAL(pszKey, "a_srs"))
             {
                 argv.AddString("-a_srs");