[gdal-dev] GSoC GDAL2Tiles: MapTiler.org, Google Maps Projection Web, Source Code

Guillaume Sueur guillaume.sueur at neogeo-online.net
Mon Aug 18 17:06:37 EDT 2008

That's an awesome job actually Klokan ! Thanks for these enhancements.

Just a question after a quick look at the doc : can the input file be a
raster catalog (the gdaltindex thing) ? Raster data needing to be tiled
fur web publication are sometimes already tiled in several pieces
because of their size.

Best regards,


Klokan Petr Přidal a écrit :
> Hello everybody,
> what was done recently on GDAL2Tiles project:
> New cool example of the map generated by GDAL2Tiles:
> ----------------------------------------------------------------------------------
> I processed freely available USGS DRG map of Grand Canyon by
> GDAL2Tiles. It is a nice example of what GDAL2Tiles can generate:
> http://www.maptiler.org/example-usgs-drg-grand-canyon-gtiff/
> http://www.maptiler.org/example-usgs-drg-grand-canyon-gtiff/usgs-drg-grand-canyon.kml
> Source Code:
> --------------------
> - Fully functional source code for generating Google Maps tiles is in
> my GDAL SVN sandbox (http://svn.osgeo.org/gdal/sandbox/klokan/).
> The code was refactored a lot and it is almost prepared for merging to
> stable svn trunk gdal2tiles.py, but some coding is still needed. I am
> going to work on it during the next week.
> - I split the code into three files: 'gdal2tiles.py' (the main command
> line utility), then 'globalmaptiles.py' (classes for global
> mercator/geodetic tile bounds calculation, runs as command line
> utility too), and supporting module 'templates.py' with sample HTML
> viewers and base for generated XML files.
> - Implementation of several resampling algorithms for controlling the
> quality of tile rendering. Default is 'average' used in the GDAL's
> overview functionality. Complete list is:
> 'average','near','bilinear','cubic','cubicspline','lanczos','antialias'.
> The last one is high quality Lanczos based antialiasing algorithm, but
> you will need Python Image Library for that.
> Quality of the tile rendering is excellent I think. If you need it,
> the simple and fast 'near' it is still available.
> - GDAL2Tiles generates the sample Google Maps Based viewer, OpenLayers
> based Overlay viewer and KML files for Google Earth.
> - The utility automatically warp the raster to Google Maps projection
> (EPSG:900913) by AutoCreateWarpedVRT().
> - For raster files with palette (USGS DRG, NOAA BSB, ...) a separate
> VRT with "rasterize rgba" (GDAL 1.6dev) is recommended (later I would
> like to automate this step).
> The code is NOT YET READY for production use (now supports only RGBA -
> 4 bands - source files for example), so I recommend you to wait for
> merged version which will appear in the GDAL trunk. I will send a note
> when I will finish the merging.
> Documetation & MapTiler.org
> ------------------------------------------
> - I decided to create a special website for distributing binary
> installer and user-friendly GUI for GDAL2Tiles. I plan to develop
> wxWidget based GUI a la step by step wizard. The user-friendly project
> has name MapTiler, http://www.MapTiler.org/. Right now this web is
> used only for documentation on for raster files for templates, which I
> did not want to distribute with utility.
> I received great feedback from several users and realized that
> GDAL2Tiles utility is expected by community. That pushed me to crete
> this new project and change the name to MapTiler, which is more
> straightforward and fits to the utility probably better, especially
> for users who are not familiar with GDAL tools yet.
> GDAL2Tiles will be maintained as GDAL command line utility. MapTiler
> will implement just GUI and binary distribution.
> It would be great to have blessing of OSGEO for this project, I would
> prefer to not make separate SVN repository for such small project,
> better to keep it as part of GDAL. Would it be possible? Otherwise I
> will create Google Code project.
> - I studied the OpenGIS proposal for WMTS standard, which is related
> to TMS and I plan to send some comments to that standard. Is there
> still free OSGEO slot for OpenGIS membership?
> - I created a website about Spherical Mercator and Google Maps
> Projection and Coordinate system, for anybody who is interested to see
> the math behind tiles:
> http://www.maptiler.org/google-maps-coordinate-system-projection-epsg-900913-3785/
> Question to community:
> ----------------------------------
> - Would it be possible to keep more files separately even in the main
> GDAL tree or the utility really have to be merged to one file?
> - Is there anybody in the OpenLayers community who whould like to have
> a look at the Opacity Control for OL? I prepared the bitmaps. Is there
> any need on the OpenLayers templates? Now I am using /dev/ tree of
> OpenLayers as Virtual Earth support is broken in the stable tree
> (Safari for example).
> - Does anybody know how to correctly set the KML SuperOverlay
> maxlodpixels and fadeextents so transparency and opacity runs well and
> tiles are not disappearing in Google Earth?
> - Is anybody interested to help me with developing MapTiler (for
> example compilation of latest GDAL with all modules, preparing of
> Windows installer, help with wxPython...)
> KyngChaos (thank you!) already had a look at binaries for MacOSX, but
> we did not moved far yet as I need some functionality from 1.6dev.
> Thanks belong to everybody who gave me excellent advices on #gdal IRC,
> especially to 'FrankW' and 'even'.
> BTW I am looking for an interesting job or paid projects... any offers? ;-)
> Is there anybody who would like to support further development of
> MapTiler/GDAL2Tiles? There is plenty of features on todo list (merging
> of produced tiles with existing tile tree, support for MapCruncher
> tiles, Zoomify tiles, speed improvement - rewrite to C++ to allow
> better usage of threads on multi-core processors, driver for remote
> online TMS tiles for GDAL/MapServer to allow WMS from statically
> published tiles, etc..).
> Best regards...
> Klokan Petr Pridal
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