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<div style="color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">
<span>Hi Even,</span></div>
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<br>
</div>
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<span>I tried the open-option <span style="display: inline !important; background-color: rgb(255, 255, 255); font-size: 11pt; font-size-adjust: none">HONOUR_VALID_RANGE=NO</span> and that seems to do the trick. That netCDF driver special case could check the
flag_values metadata to see if the value is out of range but is a flagged value. But that is OK.</span></div>
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<span><br>
</span></div>
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<span><span style="font-family: "Courier New",monospace;"><span>gdalinfo NETCDF:c_gls_NDVI_201907110000_GLOBE_PROBAV_V2.2.1.nc:NDVI</span></span></span></div>
<div style="color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">
<span><span style="font-family: "Courier New",monospace;"><span>Corner Coordinates:<br>
</span>
<div>Upper Left (-180.0044643, 80.0044643) (180d 0'16.07"W, 80d 0'16.07"N)</div>
<div>Lower Left (-180.0044643, -59.9955357) (180d 0'16.07"W, 59d59'43.93"S)</div>
<div>Upper Right ( 179.9955357, 80.0044643) (179d59'43.93"E, 80d 0'16.07"N)</div>
<div>Lower Right ( 179.9955357, -59.9955357) (179d59'43.93"E, 59d59'43.93"S)</div>
<div>Center ( -0.0044643, 10.0044643) ( 0d 0'16.07"W, 10d 0'16.07"N)</div>
</span>
<div><span style="font-family: "Courier New",monospace;">Band 1 Block=3102x1207 Type=Byte, ColorInterp=Undefined</span><span><br>
</span></div>
<div><span style="font-family: "Courier New",monospace;"> NoData Value=255</span></div>
<div><span style="font-family: "Courier New",monospace;"> Offset: -0.0799999982118607, Scale:0.00400000018998981</span></div>
<div><span style="font-family: "Courier New",monospace;"> Metadata:</span></div>
<div><span style="font-family: "Courier New",monospace;"> add_offset=-0.079999998</span></div>
<div><span style="font-family: "Courier New",monospace;"> flag_meanings=Missing cloud snow sea background</span></div>
<div><span style="font-family: "Courier New",monospace;"> flag_values={251,252,253,254,255}</span></div>
<div><span style="font-family: "Courier New",monospace;"> grid_mapping=crs</span></div>
<div><span style="font-family: "Courier New",monospace;"> long_name=Normalized Difference Vegetation Index 1KM</span></div>
<div><span style="font-family: "Courier New",monospace;"> missing_value=255</span></div>
<div><span style="font-family: "Courier New",monospace;"> NETCDF_DIM_time=18088</span></div>
<div><span style="font-family: "Courier New",monospace;"> NETCDF_VARNAME=NDVI</span></div>
<div><span style="font-family: "Courier New",monospace;"> scale_factor=0.0040000002</span></div>
<div><span style="font-family: "Courier New",monospace;"> standard_name=normalized_difference_vegetation_index</span></div>
<div><span style="font-family: "Courier New",monospace;"> units=</span></div>
<div><span style="font-family: "Courier New",monospace;"> <b>valid_range={0,250}</b></span></div>
<div><span style="font-family: "Courier New",monospace;"> _FillValue=255</span></div>
<div><span></span><br>
</div>
<div>About geo-referencing, this is from the Proba-V documentation :</div>
<div><br>
</div>
</span></div>
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<span><span>"""</span></span></div>
<div style="color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">
<span><span>2.4. Data projection and geographical extents<br>
</span>
<div><span>All PROBA-V data products are projected in a standard WGS84 projection (also known as the Plate Carrée projection), similar as for the SPOT-VGT products. The 1 km Plate-Carrée projection is defined as 1/112o, with the latitude and longitude coordinates
defined at the <b>pixel centre</b>. This implies that the pixel boundaries <b>extend</b> ± 1/224o for both latitude and longitude at the pixel corners. For example, if we consider the pixel corresponding to [lon, lat]=[-180o, 75o], the upper left corner of
this pixel represents [lon, lat]=[-180o - 1/224o, 75o + 1/224o].</span></div>
<div>""" [PROBAV_Products_User_Manual.pdf]</div>
<div><br>
</div>
<div>Thank you,</div>
<div><br>
</div>
<div>Ivan</div>
<div><br>
</div>
</span></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Even Rouault <even.rouault@spatialys.com><br>
<b>Sent:</b> Friday, August 2, 2019 11:54 AM<br>
<b>To:</b> Ivan Lucena <ivan.lucena@outlook.com><br>
<b>Cc:</b> gdal-dev@lists.osgeo.org <gdal-dev@lists.osgeo.org><br>
<b>Subject:</b> Re: [gdal-dev] NetCDF driver getting wrong values if compared to HDF5</font>
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<div class="PlainText">On vendredi 2 août 2019 14:44:02 CEST Ivan Lucena wrote:<br>
> Even,<br>
> <br>
> The metadata of one file samples points to<br>
> <a href="http://land.copernicus.eu/global/products/ndvi">http://land.copernicus.eu/global/products/ndvi</a><br>
> <br>
> I wasn't able to recover my username/password so I not sure what is there.<br>
> <br>
> Another this page you can select the specific product I am using 1KM Decadal<br>
> NDVI but without login in I can tell if it is going to download the .nc<br>
> file:<br>
> <br>
> <a href="https://land.copernicus.vgt.vito.be/PDF/portal/Application.html#Browse;Root=">
https://land.copernicus.vgt.vito.be/PDF/portal/Application.html#Browse;Root=</a><br>
> 513186;Collection=1000085;DoSearch=true;Time=NORMAL,NORMAL,1,APRIL,1998,2,AU<br>
> GUST,2019<br>
> <br>
> Can you give it a try?<br>
> <br>
<br>
OK, this is due to the fact that the netCDF driver is doing a special <br>
processing with the valid_range metadata item. It will set pixel values <br>
outside of the range defined by valid_range to the nodata value.<br>
This can be disabled by the HONOUR_VALID_RANGE=NO open option.<br>
Generally, as expected, the netCDF driver will have more particular behaviour <br>
when dealing with netCDF files than the HDF5 driver (the HDF5 driver has been <br>
enhanced over years to take into account a few netCDF specific metadata items, <br>
but not that one)<br>
<br>
> Note, netCDF return this "Lower Right ( 179.9955357, -59.9955357)<br>
> (179d59'43.93"E, 59d59'43.93"S)" while the documentation mention exact "<br>
> Polygon<br>
> -60 180 80 180 80 -180 -60 -180 -60 180". It looks like a half pixel<br>
> difference, do you see a problem with that?<br>
<br>
No, if you look at the actual range with ncdump for longitude, you'll get<br>
<br>
lon = -180, -179.991071428571, [...]<br>
179.982142857634, 179.991071429063 ;<br>
<br>
and GDAL normalizes the netCDF pixel-center convention to its usual pixel-<br>
corner convention.<br>
<br>
Even<br>
<br>
-- <br>
Spatialys - Geospatial professional services<br>
<a href="http://www.spatialys.com">http://www.spatialys.com</a><br>
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