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<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>You could use
gdal_translate (</span></font><a href="http://www.gdal.org/gdal_translate.html"><font
color=black><span lang=EN-GB style='color:windowtext;text-decoration:none'>http://www.gdal.org/gdal_translate.html</span></font></a><span
lang=EN-GB>) </span><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>to decrease rasters
resolution, and then gdal_merge (</span></font><a
href="http://www.gdal.org/gdal_merge.html"><font color=black><span lang=EN-GB
style='color:windowtext;text-decoration:none'>http://www.gdal.org/gdal_merge.html</span></font></a><span
lang=EN-GB>)</span><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'> to create mosaic. The
process could be scripted (but in Windows some gdal commands does not accept
jolly characters).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>You iterate this process
some times and at every step you create a tile index. Every tile index is a Mapserver
LAYER, and all of the layers belong to the same GROUP, which will be used as “the”
layer in the query to Mapserver. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>Does this help u ?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'> Piero<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span lang=EN-US
style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</span></font></b><font
size=2 face=Tahoma><span lang=EN-US style='font-size:10.0pt;font-family:Tahoma'>
UMN MapServer Users List [mailto:MAPSERVER-USERS@LISTS.UMN.EDU] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Rahkonen Jukka<br>
<b><span style='font-weight:bold'>Sent:</span></b> giovedì 13 dicembre 2007
9.53<br>
<b><span style='font-weight:bold'>To:</span></b> MAPSERVER-USERS@LISTS.UMN.EDU<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [UMN_MAPSERVER-USERS]
ECW Pyramid</span></font><span lang=EN-US><o:p></o:p></span></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>Hi,</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>To my understandment and experience it is
unnecessary to have anything like ECW pyramids if you mean by that the same
thing as with Geotiffs, for example. That is, downsampled versions of
individual image files. ECW has a wavelet based internal
system for getting the same effect and it works fine.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>Another thing is that if you are looking
your site through tile index and you have zoomed out very far then pyramid
layers (or overviews or whatever they are called) do not help very
much. In this case MapServer has to open a bunch of physical files
from the file system, perhaps tens of image files, and that will ineviatably
slow down the response time. What will help in this case is a
separate, radically downsampled image that covers large area of your imagery.
For example, we have often sites which are 50 km by 50 km in
size and they hold 100 aerial images with 0.5 metre pixel
size. Zooming to whole site through tile index means that all the 100
files must be opened and it is for sure always slow with any file format and
whether we have fine internal pyramids or not. Pyramids do help a
bit but the key to the speed is to avoin opening so many files
from disk. What we use to do is to create a quick look image with
something like 10 metre pixel size and use that until the user has zoomed in so
close that the resolution is not good enough. At that moment only 1-4
original images must be opened through tileindex and that goes fast. </span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>A simple way to create a quick
look image is to define Geotiff outputformat in the mapfile and ask MapServer
to send the image with whole site extents with some reasonable width and
height.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>-Jukka Rahkonen-</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><b><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>Lähettäjä:</span></font></b><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> UMN
MapServer Users List [mailto:MAPSERVER-USERS@LISTS.UMN.EDU] <b><span
style='font-weight:bold'>Puolesta </span></b>José Ramón López<br>
<b><span style='font-weight:bold'>Lähetetty:</span></b> 12. joulukuuta 2007
14:09<br>
<b><span style='font-weight:bold'>Vastaanottaja:</span></b>
MAPSERVER-USERS@LISTS.UMN.EDU<br>
<b><span style='font-weight:bold'>Aihe:</span></b> [UMN_MAPSERVER-USERS] ECW
Pyramid</span></font><o:p></o:p></p>
<blockquote style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt;
margin-left:3.75pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt'>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hi List.<br>
<br>
I have populated a raster layer using a Tileindex made from ECW Files. This
layer is visible 1:1000 scale with MAXSCALE parameter.<br>
As is not possible to create ECW pyramids. Whe have got another raster layer
resampling these ECW files. <br>
We would like to populate a single raster layer that uses one tile index
created from the resampled ECW, visible at 1:10000 scale (and smaller), and
another tileindex from the original ECW files visible at bigger scales. <br>
Is it possible? If not, please tell me how could I do something similar.<br>
<br>
Tnaks.<o:p></o:p></span></font></p>
</blockquote>
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