[Qgis-user] map collars

[Chris h]

Greets:

Just a long shot question. I have a number of NOAA charts that I would like to 
remove the collars from. Is there any combination of plugins and methods 
available for qgis that would allow me to accomplish this task. 

Best regards and thanks. 

-- 
/ch
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Re: [Qgis-user] map collars

[Paolo Cavallini]

Chris h ha scritto:

> Just a long shot question. I have a number of NOAA charts that I would like 
> to 
> remove the collars from. Is there any combination of plugins and methods 
> available for qgis that would allow me to accomplish this task. 

sorry about my ignorance, but what is a map collar?
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Paolo Cavallini: http://www.faunalia.it/pc
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Re: [Qgis-user] map collars

[Paolo Cavallini]

Chris h ha scritto:

> No apology necessary. Map collars are the white borders around maps that are 
> typically distributed from governmental sources in raster format. In order to 
> stitch or glue charts together you need to remove the collars. (white area)

Oh, that can be easy: for displaying purposes, just set the white value
to null, in the raster properties dialogue. If you want to permanently
set the white to NULL, you can use gdal for this.
All the best.
-- 
Paolo Cavallini: http://www.faunalia.it/pc
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Re: [Qgis-user] map collars

[John C. Tull]

Although, this approach can be problematic if white is important for  
properly displaying the map information. E.g., USGS topographic maps  
use a white background for the map and a white collar. My solution was  
to hand select the collar in Gimp, make it a unique color (magenta or  
something), then apply the transparency to that color. This is not fun  
if you have many maps to work with.


John

On Mar 18, 2009, at 4:17 AM, Paolo Cavallini wrote:


Chris h ha scritto:

No apology necessary. Map collars are the white borders around maps  
that are
typically distributed from governmental sources in raster format.  
In order to
stitch or glue charts together you need to remove the collars.  
(white area)


Oh, that can be easy: for displaying purposes, just set the white  
value

to null, in the raster properties dialogue. If you want to permanently
set the white to NULL, you can use gdal for this.
All the best.
--
Paolo Cavallini: http://www.faunalia.it/pc
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Re: [Qgis-user] map collars

[MS]

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 maps?


Mark

On Mar 18, 2009, at 3:28 PM, "John C. Tull"   
wrote:


Although, this approach can be problematic if white is important for  
properly displaying the map information. E.g., USGS topographic maps  
use a white background for the map and a white collar. My solution  
was to hand select the collar in Gimp, make it a unique color  
(magenta or something), then apply the transparency to that color.  
This is not fun if you have many maps to work with.


John

On Mar 18, 2009, at 4:17 AM, Paolo Cavallini wrote:


Chris h ha scritto:

No apology necessary. Map collars are the white borders around  
maps that are
typically distributed from governmental sources in raster format.  
In order to
stitch or glue charts together you need to remove the collars.  
(white area)


Oh, that can be easy: for displaying purposes, just set the white  
value
to null, in the raster properties dialogue. If you want to  
permanently

set the white to NULL, you can use gdal for this.
All the best.
--
Paolo Cavallini: http://www.faunalia.it/pc
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Re: [Qgis-user] map collars

[Chris h]

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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Re: [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  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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Re: [Qgis-user] map collars

[Agustin Lobo]

...and would be so nice having a GUI in QGIS for gdal_rasterize and the 
rest of

gdal utilities!

Agus

Jamie Adams wrote:
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 > 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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fn:Agustin Lobo
n:Lobo;Agustin
org:Institut de Ciencies de la Terra "Jaume Almera" CSIC
adr:;;Lluis Sole Sabris s/n;Barcelona;;08028;Spain
email;internet:agustin.l...@ija.csic.es
url:http://www.ija.csic.es/gt/obster
version:2.1
end:vcard

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