[GRASS-dev] [GRASS GIS] #3130: r.out.gdal: add alpha channel support

[GRASS GIS]

#3130: r.out.gdal: add alpha channel support
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  Reporter:  neteler      |      Owner:  grass-dev@…
      Type:  enhancement  |     Status:  new
  Priority:  normal       |  Milestone:  7.2.0
 Component:  Raster       |    Version:  svn-releasebranch72
Resolution:               |   Keywords:  r.out.gdal
       CPU:  Unspecified  |   Platform:  Unspecified
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Comment (by neteler):

 Replying to [comment:1 mmetz]:
 > Replying to [ticket:3130 neteler]:
 ...
 > According to Landsat metadat, 0 is not a valid data value, valid range
 is 1 - 255. Also, r.info -r shows that 0 is not present, therefore 0 can
 be used for nodata.

 Well, this was just intended as simple example to reproduce the issue.
 Indeed I am using different data. At least there is no guarantee that 0 is
 never a valid dataset while having 8 bit to be exported.

 > > The only solution seems to be an extra alpha channel to be stored in
 the resulting GDAL file (here: GeoTIFF).
 >
 > You mean r.out.gdal should create this extra alpha channel internally?

 Yes, I thought so.

 > You could also try the PHOTOMETRIC and ALPHA creation options for
 GeoTIFF with a corresponding alpha channel created manually.

 Interesting - do you have an example? Would be happy to close this ticket
 as "worksforme" :)

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3130#comment:2>
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