[GPlates-discuss] Need to omit white space in rasters

[John Cannon]

Hi Bruce,

Yes that should be possible in the following situations...

Numerical rasters (eg, NetCDF, GeoTIFF) contain a single data value per pixel, and so any pixels equal to the no-data value specified for the raster (eg, NaN) should get rendered as transparent (ie, not drawn). An example is the age grid in the sample data (which uses no-data=NaN).

Colour rasters that support transparency (eg, PNG, BMP, TIFF) contain Red/Green/Blue/Alpha channels per pixel, and so any pixels with alpha equal to zero should get rendered as transparent (ie, not drawn). Also note that alpha values between 0 and 1.0 (where 1.0 is equivalent to 255 for 8-bit colour channels) get rendered as translucent (ie, underneath is partially visible).

Regards,
John


From: GPlates-discuss [mailto:gplates-discuss-bounces at mailman.sydney.edu.au] On Behalf Of Eglington, Bruce
Sent: Sunday, 8 April 2018 2:45 AM
To: GPlates general discussion mailing list (gplates-discuss at mail.usyd.edu.au)
Subject: [GPlates-discuss] Need to omit white space in rasters

Hi
  Is there a way to turn off or omit parts of raster images which either have no data or a background colour? In general, these appear bright white in GPlates.

Bruce




Bruce Eglington (Ph.D.)
Murray Pyke Chair
Geological Sciences
University of Saskatchewan
114 Science Place
Saskatoon
SK
S7N 5E2
Canada

bruce.eglington at usask.ca<mailto:bruce.eglington at usask.ca>
+1-306-966-5732

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