SoC 2008 - GDAL2Tiles Improvements

GDAL2Tiles creates a lighten and easy to use alternative to combination of WMS + TileCache (or GeoWebCache based on last year SoC project jTileCache).

It allows simple conversion of existing raster maps into directory structure of tiles, which after uploading on a webserver act as a map source for online viewers. A client viewer (typically a web application) is using the same protocol as when querying dynamically generated tiles from TileCache server (protocol TMS).

This Summer of Code project will improve existing GDAL2Tiles utility done in the last year.

Main part of work is in implementation of global profiles in TMS, improvement of the quality of the rendered tiles, and rewriting of HTML templates for standard viewers (based on OpenLayers, Google Maps, MS Virtual Earth, ...). All the changes will be commited to the code of GDAL2Tiles, as well as existing pending patches #2052 - (JPEG and TIFF tiles support) and #2053 (world files for tiles). This way the GDAL2Tiles utility will be ready (feature complete) for rewrite into a GDAL Driver, which is planned to be done in separate SoC Project

Support for tiles compatible with Google Maps/MSN Virtual Earth/Yahoo Maps/…

Right now the GDAL2Tiles utility doesn't support global-profiles from standard TMS. It means static tiles are not overlayable with Google Maps. This is going to change. Support for both global-mercator (based on Google Projection EPSG:900913) and global-geodetic (based on EPSG:4326) will be implemented.

GDAL2Tiles will generate tiles from supplied raster file (GeoTIFF, MrSID, ECW, ... ) with proper georeference headers. Result structure (e.g. directory with tiles, mapresource.xml containing all necessary geo-metadata and optionally an simple HTML viewerers (based on OpenLayers, Google Maps, ...), as well as KML for Google Earth SuperOverlay) can be simply published on a webserver.

Produced tiles can be used as overlay map on top of Google Map tiles or other available map sources. The simple client will allow presentation similar to this one.

Openlayers 100% TMS support, Google Maps

Improvement of TMS viewer in Patch with improvement for TMS driver would be submitted into the main tree of project (especially implementation of parser for mapresource.xml, better support for tiles on the local disk, ...).

Viewer based on Google Maps has to be improved as well, so I will implement a nice TMS client based on Google Maps API. (problematic are especially the tiles without global-mercator profile).

New suggestions for TMS Standard

Definition of the TMS Standard will be extended for pictures, restructured, extended with several suggestions, after discussion with community. Hopefully we will specify a new back compatible version with small changes (like replacement of OSGEO:41001 with EPSG:900913, extension of MapResource.xml, etc.). Such standard will be discussed and compared with OGS WMS-C.

Possible features

  • Cooperation with the second SoC Project, I am especially interested in HTTP Read driver for TMS tiles in GDAL, which will allow warping of remotely published TMS tiles, saving them back into supported data formats and hopefully also allow MapServer act as a WMS proxy for maps published as static files on a webserver.

I am open to discussion...

Student info

My name is Klokan Petr Přidal, I am a postgraduate student of Cartography at Czech Technical University in Prague. Contact is on my website and info about my work on LinkedIN profile.

Last modified 16 years ago Last modified on Mar 27, 2008, 1:00:05 PM
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