-------- Original Message --------
Subject: Free, open source map publishing tool - gdal2tiles
Date: Mon, 5 Nov 2007 12:53:40 -0000
From: Fleet, Christopher <[log in to unmask]>
To: Maps, Air Photo & Geospatial Systems Forum <[log in to unmask]>
Earlier this year there have been some useful exchanges on ways of
tiling geo-referenced map images for quicker online presentation in
Google Earth (as KML SuperOverlays), Google maps, and other software.
On behalf of a colleague, I wanted to share with the list a recently
created program, gdal2tiles, that allows a quick, simple and free way of
doing this. As this is free, non-commercial software, I hope the list
will forgive this marketing plug!
The program uses the FWTools ( http://fwtools.maptools.org/ ) set of
open source GIS software to create a tile map pyramid structure of
raster images. World files and embedded geo-referencing is used during
tile generation, but it is possible to publish an image without proper
geo-referencing too. gdal2tiles is at:
http://www.klokan.cz/projects/gdal2tiles/
Just to illustrate this, these applications below use Openlayers for
some seamed, geo-referenced series maps of Scotland, all created using
gdal2tiles:
Ordnance Survey Quarter-inch to the mile, 1921-23 -
http://geo.nls.uk/quarter/
Bartholomew half-inch to the mile, 1926-35 - http://geo.nls.uk/bart/
Ordnance Survey One Inch to the mile, Popular ed, 1921-30 -
http://geo.nls.uk/popular/
Roy Military Survey, 1747-55 - Highlands -
http://geo.nls.uk/roy-highlands/
Roy Military Survey, 1747-55 - Lowlands -
http://geo.nls.uk/roy-lowlands/
Each of these applications contains several Gb of imagery each - the OS
Popular is about 34Gb in total - but it displays quite swiftly due to
the tiled structure and display.
The OS Quarter-Inch mapping in Google Earth (
http://geo.nls.uk/OS/Quarter/Quarter.kml ) is about 5 Gb of imagery, but
gives relatively fast displays through the TMS tiling.
Klokan Petr Pridal ([log in to unmask]), who wrote the gdal2tiles program,
has several ideas for further development, including:
- support for Google Maps compatible tiles, so its possible to overlay
your map on top of Google maps
- one collection of tiles for Google Maps, Google Earth, OpenLayers,
whatever, possible with Global Mercator projection.
- Zoomify-based viewer supporting tiles from gdal2tiles.
and various ways of incorporating gdal2tiles with geo-referencing tools,
like the Metacarta rectifier: http://labs.metacarta.com/rectifier/
(although this involves writing a different program, as Metacarta is not
open-source)
Klokan Petr Pridal is very keen for this software to be used in the map
community, and for further information or advice about similar software
and projects. He also would be keen for any support for further work,
and co-operation in developing these free tools!
Chris Fleet
Deputy Map Curator
National Library of Scotland
33 Salisbury Place
EDINBURGH
EH9 1SL
United Kingdom.
Tel. 0131 623 3973
Fax. 0131 623 3971
E-mail: [log in to unmask]
View maps website: http://www.nls.uk/maps
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