[Qgis-user] Visualize Raster Timeseries with Standard Min/Max Values

[Alister Hood]

> Date: Sun, 26 Feb 2012 08:47:49 -0800 (PST)
> From: dpan <davepanitz at yahoo.com>
> Subject: [Qgis-user] Visualize Raster Timeseries with Standard Min/Max
>	Values
> To: qgis-user at lists.osgeo.org
> Message-ID: <1330274869657-4510586.post at n6.nabble.com>
> Content-Type: text/plain; charset=us-ascii
>
> Hi all,
>
> I have raster data for a single, continuous variable (e.g. tmean in May) for
> a particular region of interest. I'd like to visualize the progression of
> May tmean across several years with a grayscale or color ramp, to show how
> it changes through time.
>
> qGIS by default stretches and clips each raster's grayscale ramp to the Min
> and Max values for that raster. So each ramp has different Min/Max,
> complicating comparison between years. 
>
> I thus want to standardize the Min/Max values across the entire dataset. The
> only way I've found to do this is to determine the Max and Min values for
> the entire dataset, then enter those Min/Max values in Layer
> Properties>Style for each raster.
>
> This is obviously impractical for large datasets (even for small ones,
> really). How do I do this correctly, so I can easily generate visual
> timeseries of a variable of interest?

You should be able to just style one layer with sensible Min/Max values, save the style, and make a series of copies of the resulting .qml file, named after each raster image.  You should be able to make those copies at the command prompt with a single command ;)