[Qgis-user] map collars

[Jamie Adams]

You could create a polygon in qgis (or some automated way), find an unused
pixel value in the chart, and then use gdal_rasterize -i to burn it into the
collar area.  You can then use that as the transparency value.

On Wed, Mar 18, 2009 at 3:32 PM, Chris h <chris123 at magma.ca> wrote:

> On Wednesday 18 March 2009 16:07:18 MS wrote:
> > I realize this goes into other software on a qgis list, but I wonder
> > with GDAL or GRASS one can accomplish this.
> >
> > It is really a raster clip that would work well, especially if the
> > next step is mosaic'ing the rasters.  Are these quad ma
>
> The charts are NOAA BSB rasters.
>
> Posted the same questions to the grass list and the response was positive:
> ------------------------------------------------
> >> WIth r.in.poly you could "digitize" the area of interest, then use
> >> r.mask to remove the outside area, then r.patch everything.
> >> With a small script you could generate the ASCII polygon file
> >> for r.in.poly based on the map extent.
> --------------------------------------------------
>
> Standalone gdal will not do it, especially if you want to automate the
> process
> and have concerns with the osmerander bug which in a marine charting
> environment could be rather interesting. The charts will in fact be tiled
> and
> made available via mapserver wms.
>
> The only issue for me is that I must learn each step with each application.
> Hence I went the easy route first to see what can be done with qgis.
>
> There is a very good new program out for creating tiles, maptiler.org and
> need
> to see and learn if the datum and projection can be changed. Its basically
> a
> front end to galtiler.
>
> Thanks for all the suggestions.
>
>
> --
> /ch
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