[Qgis-developer] No data value in raster transparency list

[Radim Blazek]

On Thu, Aug 23, 2012 at 8:15 AM, Marco Hugentobler
<marco.hugentobler at sourcepole.ch> wrote:
> Hi Radim
>
> Nodata should be rendered transparent in most cases. But it could also be
> possible you want to render it differently. E.g. the interpolation plugin
> writes nodata value in case it encounters numerical problems. Then it is
> useful to have the nodata values coloured to see where problems happened.

There are other standard ways to highlight nodata:
- set background color
- set nodata pixels to a different value (r.null) and assign a color to it

If you and other users insist that it should be possible to render
nodata with a color, we have to add support for it in GUI (set color)
and renderers. Currently there is no such support.

Radim

> Maybe there are other use cases as well.
>
> Regards,
> Marco
>
> Am 22.08.2012 17:49, schrieb Radim Blazek:
>>
>> Hi,
>> does anybody know why raster no data value is automatically added to
>> transparency list in properties dialog? It makes no sense IMO. No data
>> values are always rendered as transparent, no need to define them also
>> in transparent list.
>>
>> Radim
>> _______________________________________________
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>
>
>
> --
> Dr. Marco Hugentobler
> Sourcepole -  Linux & Open Source Solutions
> Weberstrasse 5, CH-8004 Zürich, Switzerland
> marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
> Technical Advisor QGIS Project Steering Committee
>
>
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