Hi Andrea,
I have understood that PAM may contain any metadata that cannot be stored into
the file format itself.
I made a test but I honestly do not know what it proves, if anything. However,
if I tell GDAL to handle GeoTIFF as read-only and make some edits with
gdal_edit -ro -mo DATUM=WGS84 test.tif
gdal_edit -ro -scale 299 -offset 10 test.tif
then I get a tif.aux.xml file that contains
<PAMDataset>
<Metadata>
<MDI key="DATUM">WGS84</MDI>
</Metadata>
<PAMRasterBand band="1">
<Offset>10</Offset>
<Scale>299</Scale>
</PAMRasterBand>
<PAMRasterBand band="2">
<Offset>10</Offset>
<Scale>299</Scale>
</PAMRasterBand>
<PAMRasterBand band="3">
<Offset>10</Offset>
<Scale>299</Scale>
</PAMRasterBand>
</PAMDataset>
If I run the commands without -ro then the tags of the GeoTIFF file are edited
and no sidecar file appears.
-Jukka-
Lähettäjä: Andrea Aime <[email protected]>
Lähetetty: maanantai 27. toukokuuta 2019 18.59
Vastaanottaja: Rahkonen Jukka (MML) <[email protected]>
Kopio: [email protected]
Aihe: Re: [gdal-dev] Is there a reference documentation for GDALMetadata
structure?
Hi Jukka,
thank you for following up. I believe that provides information for the PAM
dataset, which
is normally a sidecar containing statistical information such as
min/max/histograms.
The GDAL metadata TIFF tag instead normally contains other information, such as
scale/offset,
band names, units, and uses a XML that has a different structure.
Looking into the code there is something around here:
https://github.com/OSGeo/gdal/blob/master/gdal/frmts/gtiff/geotiff.cpp#L13726
I see explicit treatment for scale/offset and a few others, not sure if there
is anything else?
Like, if a band had a custom name, would it show up in the GDALMetadata
structure in a significant way?
From my previous example, things like:
<Item name="Band_1">Max Band_1</Item>.
<Item name="Band_2">Min Band_1</Item>.
<Item name="Band_3">Mean Band_1</Item>.
<Item name="Band_4">SD Band_1</Item>.
<Item name="Band_5">MASD Band_1</Item>.
<Item name="Band_6">Valid Inputs</Item>.
are they actually used or just treated as "random strings"?
Looking at a GDALInfo output it looks like of the second, but maybe I'm missing
something:
Metadata:
AREA_OR_POINT=Area
Band_1=Max Band_1
Band_2=Min Band_1
Band_3=Mean Band_1
Band_4=SD Band_1
Band_5=MASD Band_1
Band_6=Valid Inputs
UNITS=m
...
Band 1 Block=10x10 Type=Int32, ColorInterp=Gray
NoData Value=-9999
Offset: 0, Scale:0.0001
Band 2 Block=10x10 Type=Int32, ColorInterp=Undefined
NoData Value=-9999
Offset: 0, Scale:0.0001
Band 3 Block=10x10 Type=Int32, ColorInterp=Undefined
NoData Value=-9999
Offset: 0, Scale:0.0001
Band 4 Block=10x10 Type=Int32, ColorInterp=Undefined
NoData Value=-9999
Offset: 0, Scale:0.0001
Band 5 Block=10x10 Type=Int32, ColorInterp=Undefined
NoData Value=-9999
Offset: 0, Scale:0.0001
Band 6 Block=10x10 Type=Int32, ColorInterp=Undefined
NoData Value=-9999
Offset: 0, Scale:0.0001
Cheers
Andrea
On Mon, May 27, 2019 at 1:11 PM jratike80
<[email protected]<mailto:[email protected]>>
wrote:
Hi,
Perhaps here
https://github.com/OSGeo/gdal/blob/master/gdal/gcore/gdalpamdataset.cpp
-Jukka Rahkonen-
geowolf wrote
> Hi,
> I was wondering if there is any documentation on what a GDALMetadata XML
> structure might contain, both in terms
> of element/attributes, and key names?
> ...
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