[Qgis-user] gdalbuildvrt - setting scale dependent visibility

[Alexandre Neto]

Graham,

You need to create the overlays (pyramids) for the virtual raster.

You can do it directly in QGIS:
 - Turn render off;
 - Load the Virtual raster;
 - Open Layer properties (right-click) and go to Pyramids
 - Select all the resolutions proposed and press Build pyramids.

Or you can do it using GDAL in the terminal or comand line.

 Have a look here:

http://linfiniti.com/2009/09/image-mosaicking-with-gdal/.

there is also a great tutorial\testing in Portuguese, maybe you can
understand it using a automatically translated version:

http://translate.google.pt/translate?sl=pt&tl=en&js=n&prev=_t&hl=pt-PT&ie=UTF-8&u=http%3A%2F%2Fblog.viasig.com%2F2010%2F01%2Fmosaicos-de-imagens-em-mapserver-com-gdal%2F&act=url

Hope this helps.

Alexandre Neto



On Thu, Dec 19, 2013 at 11:06 AM, Graham <gford2113 at outlook.com> wrote:

> Hi,
>
> When using gdalbuildvrt to create a virtual raster, is there a way to
> specify the scale dependent visibility of the vrt that is being created?
> My reason for this question is that when displaying a vrt containing a
> large
> number of rasters QGIS 2.0.1 takes a very long time to open up the Layer
> Properties dialogue.  It would be therefore be a useful timesaver to set
> the
> visibility using the gdalbuildvrt command.
>
>
>
> --
> View this message in context:
> http://osgeo-org.1560.x6.nabble.com/gdalbuildvrt-setting-scale-dependent-visibility-tp5095071.html
> Sent from the Quantum GIS - User mailing list archive at Nabble.com.
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