[Qgis-user] Map georeference question

[Nicolas Cadieux]

Hi,

You can do this 2 way.  When you are doing the georeferencing, you can select "use 0 for transparency when needed."  This can sometimes give good results but can leave some transparent pixels in the map depending on the image.  

Another way is to right click on the layer in the layer panel, to select layer properties, than to go to transparency.  You can add a temporary no data value or play with the custom transparency options.

The no data entered here is temporary and will not be used in the raster math for example.  It is for the screen rendering only.

Nicolas

> Le 12 avr. 2017 à 10:17, scott.madry [via OSGeo.org] <ml-node+s1560n5317021h12 at n6.nabble.com> a écrit :
> 
> Hello, QGIS gurus and friends.
> 
> 
> Some of my students are georeferencing historical maps in QGIS, and want to remove the black edge areas that appear after the raster arrays are warped, or at least make these and only these black areas completely transparent.  Seems a simple task?  Thanks- Scott Madry, UNC Chapel Hill, USA
> 
> 
> _______________________________________________ 
> Qgis-user mailing list 
> [hidden email] 
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user 
> 
> If you reply to this email, your message will be added to the discussion below:
> http://osgeo-org.1560.x6.nabble.com/Map-georeference-question-tp5317021.html
> To start a new topic under QGIS - User, email ml-node+s1560n4125267h38 at n6.nabble.com 
> To unsubscribe from QGIS - User, click here.
> NAML




--
View this message in context: http://osgeo-org.1560.x6.nabble.com/Map-georeference-question-tp5317021p5317073.html
Sent from the QGIS - User mailing list archive at Nabble.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20170412/fd736ab1/attachment.html>