[Qgis-user] Scale dependent visibility

[Andreas Neumann]

One option is to introduce a VRT file.

VRT is a virtual file combining several physical rasters into one logical
raster file by referencing the physical files. You can create a VRT-File
with gdal on the command line, or maybe even more comfortable with the
gdal-tools plugin.

After installing the gdaltools plugin use the "Build virtual raster" tool.

Andreas

On Mon, March 15, 2010 9:59 am, Heikki Luhamaa wrote:
> Hi,
>
> this thing I know and works perfectly well for me. But, I need to apply
> these visibility settings to several dozens of raster files at once. And
> doing this one-by-one is quite time consuming. So, it would be nice to
> have option to apply these setting to a bunch of files at once. For
> example by right mouse-click on group tab and then selection group
> properties and scale dependent visibility for whole group (dreaming...)?
> But maybe there is some kind of work-around to achieve this. I am not
> familiar with python (nor programming) but is it possible to implement
> this kind of behaviour through plug-in?
>
> Heikki
>
> On Mon, 15 Mar 2010 09:22:32 +0100 (CET)
> "Andreas Neumann" <a.neumann at carto.net> wrote:
>
>> Hi Heikki,
>>
>> For every data layer you can set the scale-dependent rendering with
>> min/max values.
>>
>> Go to layer properties --> General --> Use Scale Dependent Rendering -->
>> set min/max values.
>>
>> For correct scale calculations it is important that you correctly set
>> the
>> map units and projection parameters.
>>
>> Unfortunately, a data layer can only have one scale range, if you want
>> to
>> display the same layer with different filter and symbolization settings
>> you have to load the layer several times.
>>
>> Alternatively, you can use a WMS server to serve your raster data and
>> use
>> the scale-range settings of your mapserver. This way your users only
>> have
>> to load one layer and the server deals with the scale settings.
>>
>> Hope this helps,
>> Andreas
>>
>> On Mon, March 15, 2010 7:28 am, Heikki Luhamaa wrote:
>> > Hi all,
>> >
>> > is there somehow possible to apply "Scale dependent visibility" option
>> on
>> > several raster layers or to the whole project at once? I have several
>> > projects where I need to have open several dozens or more raster
>> layers.
>> > Despite qgis renders rasters quite quickly it would probably speed up
>> > things if I can hide them, at certain zoom level.
>> >
>> > Thanks,
>> > Heikki Luhamaa
>> > _______________________________________________
>> > Qgis-user mailing list
>> > Qgis-user at lists.osgeo.org
>> > http://lists.osgeo.org/mailman/listinfo/qgis-user
>> >
>>
>>
>> --
>> Andreas Neumann
>> http://www.carto.net/neumann/
>> http://www.svgopen.org/
>>
>
>
> --
> Heikki Luhamaa <heikkiluha at hot.ee>
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/qgis-user
>


-- 
Andreas Neumann
http://www.carto.net/neumann/
http://www.svgopen.org/