[Mapserver-users] I have some landsat 7 data that I want to tile : overlap + transparency

Fri Jan 30 21:51:35 EST 2004

Folks -

The concept of a 300 dpi image from spatial imagery is nothing more than
a convenient fiction.  EVERY WMS command produces a 300 dpi image - at a
certain output scale.

You need to define one more variable - the geographic dimensions of a
pixel.  This will let you calculate the image size you want.  Say, for
example, you want to create a 300 dpi image in which each pixel
represents 15 meters (in each dimension).  This means each inch on the
output product will be 300 x 15 meters, so your output scale is 1 inch =
300 x 15 meters or 1 inch = 300 x 15 x 39.37 inches - a scale of
1:177,165.

If you'd like to do that, and produce a 6" x 6" 300 dpi image at a
resolution of 15 meters per pixel, your WMS request asks for 6 x 300 x
15 or 27,000 meters in each dimension (in the BBOX parameter) and asks
for a WIDTH and HEIGHT of 1,800 pixels (6 inches at 300 dpi).

If you'd like the image to be 10 meters per pixel, or 30 meters per
pixel, you would request a BBOX where delta X and delta Y were both
18,000 meters or 54,000 meters respectively.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com
-----Original Message-----
From: Kralidis,Tom [Burlington] [mailto:Tom.Kralidis at ec.gc.ca] 
Sent: Friday, January 30, 2004 7:58 PM
To: 'Stephen Clark'; Frank Warmerdam
Cc: mapserver-users at lists.gis.umn.edu
Subject: RE: [Mapserver-users] I have some landsat 7 data that I want to
tile : overlap + transparency

> -----Original Message-----
> From: Stephen Clark [mailto:stephen.clark at focus.ca]
> Sent: Friday, January 30, 2004 7:57 PM
> To: Kralidis,Tom [Burlington]; Frank Warmerdam
> Cc: mapserver-users at lists.gis.umn.edu
> Subject: Re: [Mapserver-users] I have some landsat 7 data that I want 
> to tile : overlap + transparency
> 
> 
> Tom,
> 
> Is this the same as the CANIMAGE WMS layer from :
> 
> "http://wms.cits.rncan.gc.ca/cgi-bin/cubeserv.cgi?"
> 

The CanImage layer is a processed set, with no overlaps, at 15m
resolution.
The CCRS Landsat are band 743, as distributed by GeoGratis.  Same base
product, different pre-processing done to the data.  IMHO, the CanImage
product looks more seamless.

> If so I already have this layer added to MapServer.
> 
> My use of Landsat 7 Imagery is for a backdrop in my PDF files.  But I 
> cannot get the WMS server to produce a 300 dpi image so I need to copy

> them locally to produce the 300 dpi PDF files.
> 
> Do you know of a WMS command that will produce an image ad a 
> particular DPI?
> 

No, anyone else got an idea here?

..Tom

> thanks
> Stephen
> 
> ----- Original Message -----
> From: "Kralidis,Tom [Burlington]" <Tom.Kralidis at ec.gc.ca>
> To: "'Stephen Clark'" <stephen.clark at focus.ca>; "Frank Warmerdam" 
> <warmerdam at pobox.com>
> Cc: <mapserver-users at lists.gis.umn.edu>
> Sent: Friday, January 30, 2004 2:59 PM
> Subject: RE: [Mapserver-users] I have some landsat 7 data that I want 
> to tile : overlap + transparency
> 
> 
> >
> > Hi Stephen,
> >
> > What are your requirements for using the Landsat 7 Orthoimagery in 
> > MapServer?
> >
> > The CCRS WMS has the entire Landsat 7 Orthorectified Imagery 
> > collection, which is on GeoGratis, available as OGC:WMS:
> >
> > URL: http://ceoware2.ccrs.nrcan.gc.ca/cubewerx/cubeserv/cubeserv.cgi
> > Layer name: L7O_B743:CEOWARE2
> >
> > Note that this layer is also timestamped, i.e. you can
> query via TIME
> > in OGC:WMS also.  The scenes' black areas are transparent.
> >
> > Just thought it'd be easier to point to an OGC:WMS of this
> data rather
> than
> > roll your own.
> >
> > Another comment: I'd be interested, as a separate exercise, how 
> > MapServer deals with overlapping images in a given layer.
> What kind
> > of algorithm is done between scenes which overlap?
> >
> > Thanks
> >
> > ..Tom
> >
> > =========================
> > Tom Kralidis
> > Systems Scientist
> > Environment Canada
> > Tel: +01-905-336-4409
> > http://www.ec.gc.ca/cise/
> >
> > =========================
> >
> > > -----Original Message-----
> > > From: Stephen Clark [mailto:stephen.clark at focus.ca]
> > > Sent: Friday, January 30, 2004 6:52 PM
> > > To: Frank Warmerdam
> > > Cc: mapserver-users at lists.gis.umn.edu
> > > Subject: Re: [Mapserver-users] I have some landsat 7 data that I 
> > > want to tile : overlap + transparency
> > >
> > >
> > > Frank,
> > >
> > > My landsat data is from the Geogratis web site :
> > >
> > > http://geogratis.cgdi.gc.ca/download/landsat_7/ortho/geotiff/utm/
> > >
> > > Specifically these three scenes as example:
> > >
> > > http://geogratis.cgdi.gc.ca/download/landsat_7/ortho/geotiff/u
> > > tm/047021/
> > > http://geogratis.cgdi.gc.ca/download/landsat_7/ortho/geotiff/u
> > > tm/048021/
> > > http://geogratis.cgdi.gc.ca/download/landsat_7/ortho/geotiff/u
> > > tm/049021/
> > >
> > > I compressed the files to ECW and produced this layer:
> > >
> > > LAYER
> > >   NAME landsat_048_021_rgb
> > >   DATA
> > > 
> "d:/datasets/imagery/landsat/ecw/048021_0100_990804_l7_743_utm10.ecw"
> > >   TYPE RASTER
> > >   STATUS ON
> > >   TRANSPARENCY 60
> > >
> > >   # turn off the black background in the image files
> > >    OFFSITE 0 0 0
> > > END
> > >
> > >
> > > >Do all the images have the same background value?   YES 
> -- they do.
> > > There is a residual amount of black fuzziness around the scenes 
> > > after using the above OFFSITE command.
> > >
> > > Here is a LAYER file for the tiled index of Landsat scenes:
> > >
> > > LAYER
> > >   NAME landsat_tile
> > >   TILEINDEX "d:/datasets/imagery/landsat/landsat_index.shp"
> > >   TILEITEM "location"
> > >   TYPE RASTER
> > >   STATUS ON
> > >   TRANSPARENCY 60
> > >
> > >   # turn off the black background in the image files
> > >   OFFSITE 0 0 0
> > >
> > >   METADATA
> > >     WMS_TITLE "Lansdat 7 Imagery "
> > >     WMS_ABSTRACT "N/A"
> > >     WMS_SRS "EPSG:26910"
> > >   END
> > >
> > > END
> > >
> > > But this tiled layer does not have any transparency.  How would I 
> > > fix this?
> > >
> > > thanks
> > > Stephen
> > >
> > > ----- Original Message -----
> > > From: "Frank Warmerdam" <warmerdam at pobox.com>
> > > To: "Stephen Clark" <stephen.clark at focus.ca>
> > > Cc: <mapserver-users at lists.gis.umn.edu>
> > > Sent: Friday, January 30, 2004 2:31 PM
> > > Subject: Re: [Mapserver-users] I have some landsat 7 data that I 
> > > want to tile : overlap + transparency
> > >
> > >
> > > > Stephen Clark wrote:
> > > > > Hi All,
> > > > >
> > > > >
> > > > > I have some landsat 7 data that I want to tile but the scenes 
> > > > > overlap.
> > > > >
> > > > > Can I use some sort of command that can be added to the
> > > "gdaltindex"
> > > > > command to add a transparency value to these scenes
> so that the
> > > > > overlap areas can show through.
> > > >
> > > > Stephen,
> > > >
> > > > Do all the images have the same background value?  If
> so, use it
> > > > as the offsite value for the whole layer and it will be used
> > > with all the
> > > > images. The other alternative is to store the tiles in a format 
> > > > for which GDAL recognises "nodata" values, but this isn't very
> > > convenient
> > > > to arrange. There is no way to include nodata values in
> the raster
> > > > tile index.
> > > >
> > > > 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 
> > > http://lists.gis.umn.edu/mailman/listinfo/maps> erver-users
> > >
> >
> 
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