[Qgis-developer] Loading raster stats: grass/gdal slowdown?

[Agustin Lobo]

I agree with Giuseppe, stats by default should be calculated in at
most 5% of pixels,
although there should be a tool to calculate full stats and save them.
A random 5% sample is actually a better estimate of the real min,max,
because most of the time
you do not hit outliers because they a re rare by definition.

Agus

El día 28 de febrero de 2012 13:43, Giuseppe Sucameli
<brush.tyler at gmail.com> escribió:
> Hi,
>
> On Tue, Feb 28, 2012 at 1:07 PM, Alexander Bruy
> <alexander.bruy at gmail.com> wrote:
>> Right currently stretching is off by default. But collecting stats
>> is necessary not only for stretching. For example some plugins
>> needs raster statistics for their work.
>
> are you talking about approximated stats, isn't it? Because in this moment
> the QgsRasterProvider compute full stats only, so the process can require
> a lot of time.
>
> In addition, I think we should re-style the piece of the raster Layer Property
> dialog to set min/max (I know there's a ticket yet):
>
> - the checkboxs are not checked whenever at least one should be,
>
> - "Estimated (faster)" compute only approximated max/min, instead "Actual
> (slower)" compute full stats (why? shouldn't compute min/max either)?
>
> - the "Load" button is far away from the checkboxes (I thought them was
> unrelated).
>
>> 2012/2/28 Nathan Woodrow <madmanwoo at gmail.com>:
>>> I thought stretching was off by default...
>>>
>>> - Nathan
>>
>> --
>> Alexander Bruy
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>
>
>
> --
> Giuseppe Sucameli
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