[mapserver-users] Split large tiffs (topos) like TopoZone

Allan Doyle adoyle at intl-interfaces.com
Fri Oct 19 09:59:00 EDT 2001 


Ed McNierney wrote:
> 
> Allan -
> 
> I would urge anyone considering the "CSS approach" you describe to do so
> with extreme caution.  This is remarkably difficult to get working
> properly across a reasonable set of browser platforms.  Everyone's done
> it differently, the bugs are different in each release, and it's just a
> nightmare.  There's a very good reason why the map on the Digital Earth
> page you mention is at the upper-left corner of the page - it's really
> hard to make it work anywhere else on the page!

Excellent point! I'm not pushing the CSS approach so much as I was
trying to illustrate what you can do with WMS's to break out of the old
mold of needing local copies of everything.

> 
> Having "been there, done that", I would really recommend that anyone
> considering that approach instead use a small Java applet to load the
> images and display them.  Your compatibility problems will be greatly
> reduced.

Yup. Of course, doing it on the server side is probably the least risky
in terms of heterogeneous clients.

> 
>         - Ed
> 
> Ed McNierney
> Chief Mapmaker
> TopoZone.com
> ed at topozone.com
> (978) 251-4242
> 
> -----Original Message-----
> From: Allan Doyle [mailto:adoyle at intl-interfaces.com]
> Sent: Friday, October 19, 2001 8:22 AM
> To: mapserver-users at lists.gis.umn.edu
> Subject: Re: [mapserver-users] Split large tiffs (topos) like TopoZone
> 
> I think the original question/need was to be able to have DRGs "like
> TopoZone's" that John Arthur could layer his own data on top of.
> 
> If, indeed, he meant that he wants to layer his data on top of
> TopoZone's data, then since we learned (also in this thread) that
> TopoZone has a WMS, then he's home free. The idea behind WMS was to
> allow precisely this: "Map A" from source "A" can be layered onto "Map
> B" from source "B" without having to copy all the data from "A" to "B"
> or vice versa. This can be done at the client end using CSS tricks with
> layers - i.e. the client sends out two requests, one to WMS A and one to
> WMS B and can layer the result. Or it can be done using "Cascading WMS"
> techniques - WMS A behaves as a client to WMS B, pulls WMS B's layers in
> on demand, and produces the layered map for WMS A.
> 
> http://viewer.digitalearth.gov/ is a great example of the CSS approach.
> 
> http://www.cubewerx.com/demo/cubeview/cubeview.cgi is the original and
> probably the best current example of the cascading approach.
> 
> Also, not to be heretical in the mapserver-users list, but there's an
> open source implementation of a WMS geared to displaying from large
> image bases called the MIT OrthoServer at
> http://tull.mit.edu/orthoserver/  You can use it for the image layers
> and the mapserver for the other layers and cascade up through the
> mapserver.
> 
>         Allan
> 
> Stephen Lime wrote:
> >
> > Ed is quite correct (he should be, it's his site). I did the same
> thing for Minnesota (maps.dnr.state.mn.us/tomo, ~300,000 images) and it
> works very well. That script is simple perl script that doesn't use
> MapServer. However, I did use perl and MapScript to compute the 300k
> images (I think I still have the script if anyone want to take a look).
> Took a day. Can MapServer and the TOMO server work together? Possibly
> but you'd be bound by the non-MapServer application because of the
> nature of the underlying data.
> >
> > Again, TOMO and TopoZone are built to serve one layer very fast, but
> I've been using the exact same datasets (quad-based DRGs) that the
> little images were computed from in a tiled fashion to support a much
> broader range of scales and applications with great success and by
> managing a few thousand images instead of a few hundred thousand. I can
> only imagine what the TopoZone folks go through with 17 million images
> and all the projection headaches.
> >
> > Steve
> >
> > Stephen Lime
> > Data & Applications Manager
> >
> > Minnesota DNR
> > 500 Lafayette Road
> > St. Paul, MN 55155
> > 651-297-2937
> > >>> "Ed McNierney" <ed at topozone.com> 10/18/01 19:42 PM >>>
> > Folks -
> >
> > I've already mentioned to John privately that I have set up a WMS
> server
> > for topographic maps and would be interested in working with folks who
> > would either like to use WMS "end-point" clients or use MapServer as a
> > WMS client for these data layers.  These will shortly be available as
> a
> > subscription service from TopoZone, and I could use some guinea pigs.
> > If you're very cooperative, I've got some nice 1-meter DOQ data you
> can
> > use, too <g>.  Send email if you're interested; you'll be able to get
> > complete DRG or DOQ base maps for your MapServer applications without
> > buying data or disk to put it on!
> >
> > On the original point of chopping up rasters into little tiles, don't
> > get carried away.  TopoZone's current image architecture is designed
> to
> > do one very, very specific task very quickly.  The entire "map server"
> > for topozone.com (just the map-serving system, not the Web site) is
> six
> > lines of ASP VBScript code; everything is precomputed and prebuilt,
> and
> > all we serve are small image tiles at one of four fixed zoom levels.
> > The tiles are small so you can scroll the map in whole-tile increments
> > while still providing the user a reasonable degree of centering
> control.
> > The HARD part was generating all those tiles from the hodgepodge of
> > source DRG data - serving them is trivial.
> >
> > I would NOT recommend a similar approach for MapServer applications -
> > the tiles are WAY too small.  Besides the administrative hassles (I've
> > got over 17 million of the little buggers to keep track of) the
> > disk-seeking overhead is not worth it.  You can construct a very nice
> > MapServer system using much larger files.  We're currently managing a
> > few applications with topographic base maps, are we're storing one
> quad
> > (one DRG) per file; that means each TIFF file is several megabytes.
> > There's NO problem with performance IF you structure the data
> carefully.
> > I could very easily use larger TIFF images, but there's no benefit for
> > me to do that - having one output TIFF image for every input DRG makes
> > updates, bug fixes, and administration much easier.
> >
> >         - Ed
> >
> > Ed McNierney
> > Chief Mapmaker
> > TopoZone.com
> >
> > -----Original Message-----
> > From: Arthur, John [mailto:John.Arthur at voicestream.com]
> > Sent: Thursday, October 18, 2001 6:15 PM
> > To: 'kenboss'; Arthur, John
> > Cc: mapserver-users at lists.gis.umn.edu
> > Subject: RE: [mapserver-users] Split large tiffs (topos) like TopoZone
> >
> > Hmm,.. I seams my mapserver won't display rasters,...
> > I'm using 3.5 w/php_mapscript on windows2000. It(phpinfo) says tiff
> was
> > compiled in, and I get no errors.
> > I'm using the ".wld" extention and also tried TileIndex through
> > shapefiles,.. Any ideas?
> >
> > -John
> >
> > -----Original Message-----
> > From: kenboss [mailto:kenboss at dilbert.dnr.state.mn.us]
> > Sent: Thursday, October 18, 2001 4:49 PM
> > To: John.Arthur at voicestream.com
> > Cc: mapserver-users at lists.gis.umn.edu
> > Subject: RE: [mapserver-users] Split large tiffs (topos) like TopoZone
> >
> > Right, you'd lose the georeferencing with the ImageMagick approach.
> If
> > you're a
> > programmer, it shouldn't be too hard to do using one of the GDAL APIs
> > (C,
> > C++,
> > or Python).  If you're only a wannabe programmer like myself, you
> might
> > still be
> > able to hack one of the apps distributed with GDAL (such as
> > gdal_translate)
> > to
> > get what you need.  See http://www.remotesensing.org/gdal/
> >
> > --Ken
> >
> ========================================================================
> > ====
> > =
> > Ken Boss
> > Digital Image Analysis / Web Stuff       Forestry Resource Assessment
> > kenboss at dilbert.dnr.state.mn.us          Minnesota Dept. of Natural
> > Resources
> > Voice: 218 327 4449 ext. 237             413 SE 13th Street
> >
> > Fax:   218 327 4517                      Grand Rapids, MN  55744
> > USA
> >                    www.ra.dnr.state.mn.us
> >
> ========================================================================
> > ====
> > =
> >
> > >
> > > Yes, but what about the world file(.twf)?
> > >
> > > - John
> > >
> > > -----Original Message-----
> > > From: Stephen Woodbridge [mailto:woodbri at mediaone.net]
> > > Sent: Thursday, October 18, 2001 4:21 PM
> > > To: Arthur, John
> > > Cc: Mapserver-Users at Lists. Gis. Umn. Edu (E-mail)
> > > Subject: Re: [mapserver-users] Split large tiffs (topos) like
> TopoZone
> > >
> > >
> > > I believe you could do that with ImageMagick and Perl to automate
> it.
> > > You should be able to chop up each of your large maps into n x m
> > tiles.
> > >
> > > -Stephen Woodbridge
> > >  http://web-maps.org
> > >
> > > "Arthur, John" wrote:
> > > >
> > > > I would like to use topo quads in my MapServer, but it would take
> > forever
> > > to
> > > > export each quad from Delorme's 3D topoquads. So I exported large
> > 150 mb
> > > > files instead.  Is there a way to split these up into smaller
> files
> > or
> > > just
> > > > to display the large tiff in MapServer faster.  We would like
> > something
> > > like
> > > > what TopoZone.com has (Mad props to you guys @ TopoZone.com), but
> > layer
> > > our
> > > > own data on top.
> > > >
> > > > John Arthur
> > > > RF Technician
> > > > Office:   (757) 490-7221
> > > > Cellular: (757) 692-1515
> > > > Email: john.arthur at voicestream.com
> > > > _~-^-~_
> > > > VoiceStream
> > > > W I R E L E S S
> 
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Allan Doyle                         http://www.intl-interfaces.com
> adoyle at intl-interfaces.com

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allan Doyle                         http://www.intl-interfaces.com
adoyle at intl-interfaces.com

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