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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007>Hi,</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007>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></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007>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></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007>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></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007>-Jukka Rahkonen-</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=157392008-13122007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left>
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</DIV>
<DIV dir=ltr align=left><FONT face=Tahoma size=2><B>Lähettäjä:</B> UMN MapServer
Users List [mailto:MAPSERVER-USERS@LISTS.UMN.EDU] <B>Puolesta </B>José Ramón
López<BR><B>Lähetetty:</B> 12. joulukuuta 2007 14:09<BR><B>Vastaanottaja:</B>
MAPSERVER-USERS@LISTS.UMN.EDU<BR><B>Aihe:</B> [UMN_MAPSERVER-USERS] ECW
Pyramid<BR></FONT><BR></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV></DIV>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.<BR></BLOCKQUOTE></BODY></HTML>