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<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2>Simon -</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2>TILEINDEX is a MapServer/quasi-GDAL mechanism for handling
a large number of rasters as a single unit. The rasters don't need to be
the same size, and can overlap - I suspect they can even be different file
formats, although I've never tried, and they can be stored anywhere in the file
system.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2>The TILEINDEX scheme uses an ESRI shapefile (with an
optional quadtree index on it) as a spatial index for the rasters. One
polygon is generated for each raster, with that polygon representing the
bounding box of that file. The path to the raster file itself is stored as
a string attribute of the polygon. Applications use the spatial/geometry
features of the polygon to determine which input image(s) if any intersect the
area of interest for drawing.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2>It's not the same sort of thing, exactly, and there are no
tools I'm aware of for managing the individual image organization on disk.
But it works well for me. I use TILEINDEX structures to manage about
500,000 individual raster files that are about 40 terabytes altogether (haven't
counted lately <g>). It could certainly use enhancement, but it
might be a good starting point for such a project.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006> <FONT
face=Arial color=#0000ff size=2>- Ed</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=532575901-15112006><!-- Converted from text/plain format -->
<P><FONT size=2>Ed McNierney<BR>President and Chief Mapmaker<BR>TopoZone.com /
Maps a la carte, Inc.<BR>73 Princeton Street, Suite 305<BR>North Chelmsford,
MA 01863<BR>Phone: +1 (978) 251-4242<BR>Fax: +1 (978)
251-1396<BR>ed@topozone.com</FONT> </P></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> Simon Perkins [mailto:sy@perkins.net]
<BR><B>Sent:</B> Tuesday, November 14, 2006 8:52 PM<BR><B>To:</B> Ed
McNierney<BR><B>Cc:</B> Brent Fraser; Jordi Gilabert Vall;
gdal-dev@lists.maptools.org<BR><B>Subject:</B> Re: [Gdal-dev] GeoQuadTree - an
open format for storinggeoreferencedimages<BR></FONT><BR></DIV>
<DIV></DIV><BR>TIFF has some pretty serious file size limitations so wouldn't be
good for these kinds of large rasters. I'm not familiar with TILEINDEX, but is
this a MapServer related thing? Is that applicable to local image storage on the
desktop?<BR><BR>I think the GeoQuadTree idea is interesting - it doesn't rely on
large file support on the OS (not that that's a serious problem for any modern
OSes), and dealing with lots of small files could be more efficient than one
large file in some cases I would think.<BR><BR>As for PNG vs JPEG, it depends on
whether you're happy to accept lossy compression or not. For many applications,
customers are averse to losing any resolution. It might make sense to make the
underlying file format in GeoQuadTree flexible acording to application.
Actually, I'd prefer to see a format that can handle multispectral files - PNG
and JPEG are both limited to 1 or 3 bands, aren't they? Or are multiple bands
stored as separate grayscale images?<BR><BR>I would guess that with very large
rasters, some sort of pyramid scheme becomes important in addition to the
tiling, so that if you just want to get an overview of the whole image, you
don't have to read every single file. Does GeoQuadTree handle that?<BR><BR>But,
Ed is right that storing very large rasters is a not a new problem. So, what do
people do? I guess that at the high end, outfits like Google Earth use a spatial
database to organize multiple individual raster files and then stich them
together. Could somebody outline the solution used by the Virtual Terrain
project?<BR><BR>Cheers,<BR><BR>Sy<BR><BR><BR>Ed McNierney wrote:
<BLOCKQUOTE
cite=mid4BF377919225F449BB097CB76FFE9BC801987BAD@ptolemy.topozone.com
type="cite">
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<DIV dir=ltr align=left><SPAN class=804023220-14112006><FONT face=Arial
color=#0000ff size=2>Jordi -</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=804023220-14112006></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=804023220-14112006><FONT face=Arial
color=#0000ff size=2>You said you wanted to "avoid the use of tile indexes or
catalogues of images", but isn't that exactly what your XML catalogue/index
does? It seems that the GeoQuadTree format is a different form of that
same sort of structure. There are several different ways of doing this
now, including the TILEINDEX mechanism, tiled TIFF files, etc. I'm sure
there are limitations to each, but I'm not sure that yet another tiling scheme
will help.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=804023220-14112006></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=804023220-14112006><FONT face=Arial
color=#0000ff size=2>In particular, PNG is not the best format for all images,
and it's important to support other encoding mechanisms, especially
JPEG. Photographic images are huge when stored in PNG format, and JPEG
is usually a much better choice. Conversely, scanned line art and
synthetic images generally compress and store better as PNG
images.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=804023220-14112006></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=804023220-14112006>
<FONT face=Arial color=#0000ff size=2>- Ed</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=804023220-14112006>
<P><FONT size=2>Ed McNierney<BR>President and Chief Mapmaker<BR>TopoZone.com /
Maps a la carte, Inc.<BR>73 Princeton Street, Suite 305<BR>North Chelmsford,
MA 01863<BR><A class=moz-txt-link-abbreviated
href="mailto:ed@topozone.com">ed@topozone.com</A><BR>(978) 251-4242
</FONT></P></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> <A class=moz-txt-link-abbreviated
href="mailto:gdal-dev-bounces@lists.maptools.org">gdal-dev-bounces@lists.maptools.org</A>
[<A class=moz-txt-link-freetext
href="mailto:gdal-dev-bounces@lists.maptools.org">mailto:gdal-dev-bounces@lists.maptools.org</A>]
<B>On Behalf Of </B>Brent Fraser<BR><B>Sent:</B> Tuesday, November 14, 2006
3:05 PM<BR><B>To:</B> Jordi Gilabert Vall; <A class=moz-txt-link-abbreviated
href="mailto:gdal-dev@lists.maptools.org">gdal-dev@lists.maptools.org</A><BR><B>Subject:</B>
Re: [Gdal-dev] GeoQuadTree - an open format for
storinggeoreferencedimages<BR></FONT><BR></DIV>
<DIV><FONT size=2>For those interested tiling,</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2> There is similar tiling related discussion/work
going on at:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2> <A
href="http://lists.eogeo.org/mailman/listinfo/tiling"><FONT
size=3>http://lists.eogeo.org/mailman/listinfo/tiling</FONT></A> (do they
have a web page?)</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2> and </FONT></DIV>
<DIV><FONT size=2> <A
href="http://www.stereofx.org/terrain.html">http://www.stereofx.org/terrain.html</A>,
implemented in <A href="http://vterrain.org/">http://vterrain.org/</A>,
particularly VTBuilder (<A
href="http://vterrain.org/Doc/VTBuilder/overview.html">http://vterrain.org/Doc/VTBuilder/overview.html</A>)</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>Brent Fraser</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: rgb(0,0,0) 2px solid; MARGIN-RIGHT: 0px">
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal">-----
Original Message ----- </DIV>
<DIV
style="BACKGROUND: rgb(228,228,228) 0% 50%; FONT: 10pt arial; font-size-adjust: none; font-stretch: normal; -moz-background-clip: -moz-initial; -moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial"><B>From:</B>
<A title=jordi@geoquadtree.org href="mailto:jordi@geoquadtree.org">Jordi
Gilabert Vall</A> </DIV>
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>To:</B>
<A title=gdal-dev@lists.maptools.org
href="mailto:gdal-dev@lists.maptools.org">gdal-dev@lists.maptools.org</A>
</DIV>
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>Sent:</B>
Tuesday, November 14, 2006 3:25 AM</DIV>
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>Subject:</B>
[Gdal-dev] GeoQuadTree - an open format for storing
georeferencedimages</DIV>
<DIV><BR></DIV>Hi,<BR><FONT face="Arial, sans-serif"><FONT size=2><BR>Some
time ago I needed the retrieval from very large georeferenced raster images
in a OGC WMS server, and I wanted to avoid the use of tile indexes or
catalogues of images, neither a database. I started thinking of an open
format for storing arbitrarily large georeferenced images. I named this
format "GeoQuadTree", as it would be based on a quadtree of rectangular
tiles, each in PNG format on the filesystem, in a simple hierarchical
structure of folders. I wrote a command line utility for creating it,
importing from PNG/JPEG/TIFF and exporting to PNG/JPEG/TIFF/GDAL. I also
wrote a GDAL driver for this format. I tested successfully with my own WMS
server software, and on MapServer compiled with GDAL support. It worked very
well on Blue Marble Next Generation at a resolution of 15 arc-seconds, i.e.
86400x43200 pixels.</FONT></FONT>
<P style="MARGIN-BOTTOM: 0cm"><FONT face="Arial, sans-serif"><FONT
size=2>You can find more information on the project web
site:</FONT></FONT></P>
<P style="MARGIN-BOTTOM: 0cm; MARGIN-LEFT: 40px"><FONT
face="Arial, sans-serif"><FONT size=2><A
onclick="return top.js.OpenExtLink(window,event,this)"
href="http://geoquadtree.org/" target=_blank>http://geoquadtree.org/
</A></FONT></FONT></P>
<P style="MARGIN-BOTTOM: 0cm"><FONT face="Arial, sans-serif"><FONT
size=2>I'm testing the release 1.0.0, you can test it on the subversion
repository if you want (I haven't packaged it yet).<BR></FONT></FONT></P>
<P style="MARGIN-BOTTOM: 0cm"><FONT face="Arial, sans-serif"><FONT size=2>I
think it's a useful format, open, very easy to use, and very efficient (in
terms of response time).</FONT></FONT></P>
<P style="MARGIN-BOTTOM: 0cm"><FONT face="Arial, sans-serif"><FONT size=2>Do
you think it could be useful for you ? Would you like to include it on
GDAL's next release ?</FONT></FONT></P><SPAN class=sg>
<P style="MARGIN-BOTTOM: 0cm"><FONT face="Arial, sans-serif"><FONT
size=2>jordi at geoquadtree org</FONT></FONT></P></SPAN>
<P></P>
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