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netCDF: fix writing datasets with non-axis aligned geotransform #13911

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netCDF: fix writing datasets with non-axis aligned geotransform #13911

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75 changes: 75 additions & 0 deletions autotest/gdrivers/netcdf.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6893,3 +6893,78 @@ def test_netcdf_open_geotransform_gt5_positive():
[440720.0, 60.0, 0.0, 3751320.0, 0.0, -60.0]
)
assert ds.GetRasterBand(1).Checksum() == 4672


###############################################################################
#


@pytest.mark.parametrize(
"options,expected_gt,expected_cs,expected_warp_gt,expected_warp_cs",
[
(
[],
(1841001.75, 1.5, -5.0, 1144003.25, -5.0, -1.5),
4672,
(1840901.75, 5.2201532544552744, 0.0, 1144003.25, 0.0, -5.2201532544552744),
4454,
),
(
["WRITE_LONLAT=YES"],
(1841001.75, 1.5, -5.0, 1144003.25, -5.0, -1.5),
4672,
(
1840898.6923189342,
5.245503735406323,
0.0,
1144003.2801153609,
0.0,
-5.245503735406323,
),
4512,
),
(
["WRITE_BOTTOMUP=NO"],
(1840901.75, 1.5, 5.0, 1143973.25, -5.0, 1.5),
4855,
(1840901.75, 5.2201532544552744, 0.0, 1144003.25, 0.0, -5.2201532544552744),
4454,
),
(
["WRITE_LONLAT=YES", "WRITE_BOTTOMUP=NO"],
(1840901.75, 1.5, 5.0, 1143973.25, -5.0, 1.5),
4855,
(
1840901.2295569642,
5.249091373447578,
0.0,
1144004.0234124723,
0.0,
-5.249091373447578,
),
4443,
),
],
)
def test_netcdf_write_non_axis_aligned_geotransform(
tmp_path, options, expected_gt, expected_cs, expected_warp_gt, expected_warp_cs
):

src_ds = gdal.Open("../gcore/data/geomatrix.tif")
gdal.GetDriverByName("netCDF").CreateCopy(
tmp_path / "out.nc", src_ds, options=options
)
ds = gdal.Open(tmp_path / "out.nc")
assert ds.GetGeoTransform() == pytest.approx(expected_gt)
assert ds.GetRasterBand(1).Checksum() == expected_cs

if "WRITE_LONLAT=YES" in options:
warped_ds = gdal.Warp(
"", ds, options="-of MEM -to METHOD=GEOLOC_ARRAY -t_srs EPSG:32611"
)
else:
warped_ds = gdal.Warp(
"", ds, options="-of MEM -to METHOD=GEOTRANSFORM -t_srs EPSG:32611"
)
assert warped_ds.GetGeoTransform() == pytest.approx(expected_warp_gt)
assert warped_ds.GetRasterBand(1).Checksum() == expected_warp_cs
156 changes: 95 additions & 61 deletions frmts/netcdf/netcdfdataset.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5620,31 +5620,26 @@ CPLErr netCDFDataset::AddProjectionVars(bool bDefsOnly,
return CE_Failure;

// Optional GDAL custom projection tags.
if (bWriteGDALTags)
if (bWriteGDALTags && bWriteGeoTransform && m_bHasGeoTransform)
{
std::string osGeoTransform = m_gt.ToString(" ");
GDALGeoTransform gt(m_gt);
if (!bBottomUp)
{
// Change origin from top to bottom and sign of coefficients
// indexed by row
gt.yorig += nRasterYSize * gt.yscale;
gt.xorig += nRasterYSize * gt.xrot;
gt.xrot = -gt.xrot;
gt.yscale = -gt.yscale;
}
std::string osGeoTransform = gt.ToString(" ");
CPLDebug("GDAL_netCDF", "szGeoTransform = %s",
osGeoTransform.c_str());

// if( strlen(pszProj4Defn) > 0 ) {
// nc_put_att_text(cdfid, NCDFVarID, "proj4",
// strlen(pszProj4Defn), pszProj4Defn);
// }

// For now, write the geotransform for back-compat or else
// the old (1.8.1) driver overrides the CF geotransform with
// empty values from dfNN, dfSN, dfEE, dfWE;

// TODO: fix this in 1.8 branch, and then remove this here.
if (bWriteGeoTransform && m_bHasGeoTransform)
{
{
const int status = nc_put_att_text(
cdfid, NCDFVarID, NCDF_GEOTRANSFORM,
osGeoTransform.size(), osGeoTransform.c_str());
NCDF_ERR(status);
}
}
const int status = nc_put_att_text(
cdfid, NCDFVarID, NCDF_GEOTRANSFORM, osGeoTransform.size(),
osGeoTransform.c_str());
NCDF_ERR(status);
}

// Write projection variable to band variable.
Expand All @@ -5657,7 +5652,13 @@ CPLErr netCDFDataset::AddProjectionVars(bool bDefsOnly,
const bool bIsRotatedPole =
pszCFProjection != nullptr &&
EQUAL(pszCFProjection, ROTATED_POLE_VAR_NAME);
if (bIsRotatedPole)

if (m_bHasGeoTransform && !m_gt.IsAxisAligned())
{
// Do not write X/Y coordinate arrays
}

else if (bIsRotatedPole)
{
// Rename dims to rlat/rlon.
papszDimName
Expand Down Expand Up @@ -5873,49 +5874,55 @@ CPLErr netCDFDataset::AddProjectionVars(bool bDefsOnly,
return CE_Failure;
}

// Get Y values.
const double dfY0 = (!bBottomUp) ? m_gt.yorig :
// Invert latitude values.
m_gt.yorig + (m_gt.yscale * nRasterYSize);
const double dfDY = m_gt.yscale;
// Make sure we are in data mode.
SetDefineMode(false);

for (int j = 0; j < nRasterYSize; j++)
int status = NC_NOERR;

if (m_gt.IsAxisAligned())
{
// The data point is centered inside the pixel.
if (!bBottomUp)
padYVal[j] = dfY0 + (j + 0.5) * dfDY;
else // Invert latitude values.
padYVal[j] = dfY0 - (j + 0.5) * dfDY;
}
startX[0] = 0;
countX[0] = nRasterXSize;
// Get Y values.
const double dfY0 =
(!bBottomUp) ? m_gt.yorig :
// Invert latitude values.
m_gt.yorig + (m_gt.yscale * nRasterYSize);
const double dfDY = m_gt.yscale;

// Get X values.
const double dfX0 = m_gt.xorig;
const double dfDX = m_gt.xscale;
for (int j = 0; j < nRasterYSize; j++)
{
// The data point is centered inside the pixel.
if (!bBottomUp)
padYVal[j] = dfY0 + (j + 0.5) * dfDY;
else // Invert latitude values.
padYVal[j] = dfY0 - (j + 0.5) * dfDY;
}
startX[0] = 0;
countX[0] = nRasterXSize;

for (int i = 0; i < nRasterXSize; i++)
{
// The data point is centered inside the pixel.
padXVal[i] = dfX0 + (i + 0.5) * dfDX;
}
startY[0] = 0;
countY[0] = nRasterYSize;
// Get X values.
const double dfX0 = m_gt.xorig;
const double dfDX = m_gt.xscale;

// Write X/Y values.
for (int i = 0; i < nRasterXSize; i++)
{
// The data point is centered inside the pixel.
padXVal[i] = dfX0 + (i + 0.5) * dfDX;
}
startY[0] = 0;
countY[0] = nRasterYSize;

// Make sure we are in data mode.
SetDefineMode(false);
// Write X/Y values.

CPLDebug("GDAL_netCDF", "Writing X values");
int status =
nc_put_vara_double(cdfid, nVarXID, startX, countX, padXVal);
NCDF_ERR(status);
CPLDebug("GDAL_netCDF", "Writing X values");
status =
nc_put_vara_double(cdfid, nVarXID, startX, countX, padXVal);
NCDF_ERR(status);

CPLDebug("GDAL_netCDF", "Writing Y values");
status =
nc_put_vara_double(cdfid, nVarYID, startY, countY, padYVal);
NCDF_ERR(status);
CPLDebug("GDAL_netCDF", "Writing Y values");
status =
nc_put_vara_double(cdfid, nVarYID, startY, countY, padYVal);
NCDF_ERR(status);
}

if (pfnProgress)
pfnProgress(0.20, nullptr, pProgressData);
Expand Down Expand Up @@ -5979,10 +5986,37 @@ CPLErr netCDFDataset::AddProjectionVars(bool bDefsOnly,
if (!bHasGeoloc)
{
// Fill values to transform.
for (int i = 0; i < nRasterXSize; i++)
if (m_gt.IsAxisAligned())
{
for (int i = 0; i < nRasterXSize; i++)
{
padLatVal[i] = padYVal[j];
padLonVal[i] = padXVal[i];
}
}
else
{
padLatVal[i] = padYVal[j];
padLonVal[i] = padXVal[i];
for (int i = 0; i < nRasterXSize; i++)
{
if (!bBottomUp)
{
padLatVal[i] = m_gt.yorig +
(i + 0.5) * m_gt.yrot +
(j + 0.5) * m_gt.yscale;
padLonVal[i] = m_gt.xorig +
(i + 0.5) * m_gt.xscale +
(j + 0.5) * m_gt.xrot;
}
else
{
padLatVal[i] =
m_gt.yorig + (i + 0.5) * m_gt.yrot +
(nRasterYSize - j - 0.5) * m_gt.yscale;
padLonVal[i] =
m_gt.xorig + (i + 0.5) * m_gt.xscale +
(nRasterYSize - j - 0.5) * m_gt.xrot;
}
}
}

// Do the transform.
Expand Down Expand Up @@ -6041,7 +6075,7 @@ CPLErr netCDFDataset::AddProjectionVars(bool bDefsOnly,
} // Projected

// If not projected/geographic and has geoloc
else if (!bIsGeographic && bHasGeoloc)
else if (!bIsGeographic && bHasGeoloc && m_gt.IsAxisAligned())
{
// Use
// https://cfconventions.org/Data/cf-conventions/cf-conventions-1.9/cf-conventions.html#_two_dimensional_latitude_longitude_coordinate_variables
Expand Down
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