[Qgis-developer] color ramps for vector graduated symbols (ticket #782)

[Marco Hugentobler]

Hi Matthew and Tim,

>Looking over some color ramp formats, it looks like the GMT .cpt format is 
>the most flexible and allows you to define either continuous or discrete RGB 
>ramps across any range of z-values. Since there is no easy quick flag to 
>specify a discrete vs continuous color ramp in the cpt file itself, the 
>easiest way to differentiate may be to store them in separate folders within 
>a main color ramp directory. 
>prefix/share/qgis/ramps/discrete prefix/share/qgis/ramps/continuous

Another possibility would be to extend the continuous renderer in qgis and 
apply a discrete ramp for 'graduated symbol' and a continuous ramp 
for 'continuous color' renderer.

> The MatLab colour map editor is show here (scroll down a little for a
> screenie):
>
> http://tinyurl.com/27gbra

That looks great!

I'll try to take a look at the patch on Saturday.

Regards,
Marco

On Thursday 01 November 2007 03:19:51 Tim Sutton wrote:
> Hi
>
> Are you guys familiar with MatLab? I was hoping we could at some point
> implement a colour ramp editor similar to what they have. Also, it
> would be great to include Peter Ersts (Raster maintainer) in this
> process so we could use the same markup system in both raster and
> vector implementations (where applicable).
>
> The MatLab colour map editor is show here (scroll down a little for a
> screenie):
>
> http://tinyurl.com/27gbra
>
> Regards
>
> Tim
>
> 2007/10/25, Marco Hugentobler <marco.hugentobler at karto.baug.ethz.ch>:
> > Hi Perrygeo,
> >
> > A flexible solution for color ramps as you describe it in ticket 782
> > would be a really great enhancement for qgis.
> >
> > >The remaining questions are:
> > > - what file format works to define the color ramps? have to allow for
> > > all 4 of the above types. As much as possible, leverage existing
> > > formats like gmt and grass color ramps.
> > >
> >  >- how do the ramps get "registered" with qgis so that they can be made
> > >
> > >available to the user?
> > >- how do they get integrated with the UI? preferably a dropdown list of
> > > color ramps with a small representative image of the ramp itself.
> > > - how to we implement the algorithm to determine the rgb color for
> > > ramps of type #1 and #2?
> >
> > Registered ramps could be stored in a dedicated directory under
> > share/qgis, similar to the way it is done with the svg markers.
> >
> > Hopefully you can find a good storage format for the ramps. If there is
> > no format that meets all your requirements, you could still design your
> > own xml based language  (crml = color ramp markup language)
> >
> > Regards,
> > Marco
> >
> >
> >
> >
> > --
> > Dr. Marco Hugentobler
> > Institute of Cartography
> > ETH Zurich
> > Technical Advisor QGIS Project Steering Committee
> > marco.hugentobler at karto.baug.ethz.ch
> > _______________________________________________
> > Qgis-developer mailing list
> > Qgis-developer at lists.qgis.org
> > http://lists.qgis.org/cgi-bin/mailman/listinfo/qgis-developer



-- 
Dr. Marco Hugentobler
Institute of Cartography
ETH Zurich
Technical Advisor QGIS Project Steering Committee
marco.hugentobler at karto.baug.ethz.ch