[gdal-dev] Is there a reference documentation for GDALMetadata structure?

[Andrea Aime]

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 <
jukka.rahkonen at maanmittauslaitos.fi> 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?
> > ...
>
>
>
>
>
> --
> Sent from: http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html
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