[Mapserver-users] EXTENSION parameter in OUTPUTFORMAT removed?

[randy james]

Hi

I'm also have the problem of my rasters causing the
vectors to be rendered gray. I have well over 300
orthophotos, each at least 160Mb, making it quite time
consuming to convert all of them to 32 colors as
suggested.

>   o I could implementing a processing directive
> forcing the greyscale
>     colormap allocator to use a reduced number of
> colors.


I like the idea of implementing a processing
directive, but maybe for more colors than 6 as
suggested. Since we are using the Orthophotos as a
research tool, and some forest types are very close in
color, the more the better. We use an overhead
projector on a laptop while researching, making
Mapserver a powerful tool for forestry research. I
know that I do not see the colors that our trained
forest tech. does, so I cannot say how many colors can
be allocated.

Cheers
Randy


--- Frank Warmerdam <warmerdam at pobox.com> wrote:
> Vinko Vrsalovic wrote:
> > Two OUTPUTFORMAT curiosities:
> > 
> > 1.- is EXTENSION parameter documented in the
> mapfile reference not
> > present?
> > 
> > PHP Warning:  MapServer Error in
> loadOutputFormat(): (EXTENSION):(6)
> >  in /var/www/html/sexta2.ms/index.php on line 23
> > 
> > The map file:
> > 
> > MAP
> >         OUTPUTFORMAT
> > 		NAME png24
> > 	        DRIVER "GD/PNG"
> > 	        MIMETYPE "image/png"
> > 	        IMAGEMODE RGB
> > 	        EXTENSION "png"
> >         END
> > END
> 
> Vinko,
> 
> It seems I accidently omitted implementing this
> feature even though I
> documented.  I will implement it in CVS soon and
> email you.
> 
> > 2.- I rendered a map with vectors and a raster 8
> bits B/W layer. If I
> > used the default PNG outputformat, the vectors got
> rendered in B/W also,
> > if i turned the raster layer off, the colors were
> normal, if I turned on 
> > the raster layer, all was rendered in B/W.
> 
> The problem is that the greyscale raster layer is
> grabbing 256 greyscale
> colors for rendering itself.  There are various
> possible solutions to this:
> 
>   o Use 24bit output.
>   o Somehow cause your desired vector colors to be
> pre-allocated so the
>     raster doesn't get the whole colormap.
>   o Convert your greyscale data to a pseudo-colored
> format and compress
>     down to a reduced number of colors as part of
> this process .. I find
>     32 levels of grey is plenty for must greyscale
> display.
>   o I could implementing a processing directive
> forcing the greyscale
>     colormap allocator to use a reduced number of
> colors.
> 
> Let me know if you would like me to do the last
> item.  There are various
> ways it could be implemented.  One is to give the
> raster color allocator
> a "threshold" within which it would consider an
> existing color a match.
> For instance, if you gave a color threshold of 6
> then only about 256/3
> greyscale values would be allocated.  This would
> also apply to pseudocolored
> images that have alot of colors that are very close
> to one another.
> 
> Best regards,
> 
> -- 
>
---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank
> Warmerdam, warmerdam at pobox.com
> light and sound - activate the windows |
> http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial
> Programmer for Rent
> 
> 
> _______________________________________________
> Mapserver-users mailing list
> Mapserver-users at lists.gis.umn.edu
>
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