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

Guillaume Sueur guillaume.sueur at neogeo-online.net
Tue Aug 19 04:31:44 EDT 2008

I'm talking about 10 to 100 GigaBytes datasets, with which it doesn't
seem reasonnable to generate a single merged file !

Couldn't gdal2tiles parse a whole directory ?



Klokan Petr Přidal a écrit :
> Hi Guillaume,
> Thank you for positive feedback ;-)
>> 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.
> I don't think you can use gdaltindex with other gdal tools (like
> gdal_transform) either.
> gdaltindex is used by UNM MapServer but not by other GDAL tools, as I know.
> You would need to use VRT for combining several rasters into one...
> Use gdal_vrtmerge.py, it has similar syntax like gdaltindex. It is in
> the source under /swig/python/samples/.
> Result can be passed then to gdal2tiles and it should run well I hope.
> Is there any plan to merge gdal_vrtmerge into "gdal_merge -of VRT"?
> Best regards
> Klokan
>> Best regards,
>> Guillaume
>> 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
>>> _______________________________________________
>>> gdal-dev mailing list
>>> gdal-dev at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
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