wiki:WKTRaster

Version 165 (modified by pracine, 9 years ago) (diff)

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PostGIS Raster Home Page (formerly WKT Raster)

What's new about PostGIS Raster?

February 14, 2011
Two plugins to display PostGIS rasters!
Thanks to Maurício de Paulo, there is now a plugin to display PostGIS rasters in QGIS. Look for "wktraster" in the QGIS plugin page and Mauricio's article (if you can decrypt portuguese!). Same for gvSIG the popular spanish open source GIS! Nacho Brodin has developed a plugin to display raster stored in PostGIS. See the page of the project. On our side we are woking fixing bugs and implementing ST_MapAlgebra. See you at the Code Sprint in Montréal (march 15-18)!

September 15, 2010
WKT Raster becomes THE new PostGIS raster type!
It's official! The WKT Raster extension will become the new PostGIS RASTER type in PostGIS 2.0 planned for next april. The PostGIS and the WKT Raster team met at the FOSS4G friday's code sprint and decided that WKT Raster was mature enough to bring interesting new functionalities to PostGIS. A new MapAlgebra function should be added for this release. Congratulation to the whole team for all the work accomplished!

August 11, 2010
PostGIS WKT Raster at FOSS4G
There should be a lot of discussion about PostGIS WKT Raster at FOSS4G, the most important conference for free and open source software for geomatics, as both Pierre Racine and Jorge Arévalo presentations have been selected by the attendees. Pierre will first introduce the project in a presentation entitled “Introducing PostGIS WKT Raster: Seamless raster/vector operations in a spatial database” and Jorge will present the result of its meticulous study of the difference between PostGIS WKT Raster and Oracle GeoRaster in a presention entitled “PostGIS WKT Raster. An Open Source alternative to Oracle GeoRaster”. You can already read Jorge’s first impression in his first article in a series. CU September 6th 2010 in Barcelona!

June 11, 2010
A tutorial and a book!
The PostGIS in Action chapter on PostGIS WKT Raster is out! Thanks to Regina Obe and Leo Hsu, there is already a good amount of literature on WKT Raster and this makes WKT Raster to be a little bit more in the PostGIS family. Pierre Racine has also written a tutorial on how to import and intersect a huge raster coverage with a vector coverage. Your raster coverage is huge and you can't work with it in your favorite GIS platform? Read the tutorial! You will be amazed by the simplicity and the speed of the intersection functions. Good reading!

February 22, 2010
A third company join the WKT Raster team!
The award-winning GIS software development firm, Avencia, specializing in web-based geographic analysis, visualization and modeling applications, decided to invest in WKT Raster development. The company sent David Zwarg and Jeff Adams to the Code Sprint 2010 in NY. Jeff worked on PostGIS and David helped with many WKT Raster base functions. David committed himself to work on many other WKT Raster functions in the near future. His main task will be to design and implement the ST_MapAlgebra() and the ST_Resample() functions. Welcome David!

December 10, 2009
Tyler Erickson speaks about his need for PostGIS WKT Raster at FOSS4G 2009
Tyler Erickson, Research Scientist at the Michigan Tech Research Institute presented his research project at FOSS4G 2009 in Sydney, Australia. Tyler uses GeoDjango and PostGIS to visualise the results of CO2 simulation models directly in Google Earth. WKT Raster would enable him to easily do raster/vecter spatial analysis from his web application. Tyler's project was selected as one of the professional winners in Google’s 2009 KML in Research Competition.

December 4, 2009
Jorge Arevalo full time on WKT Raster!
Jorge Arevalo who developped the first version of the GDAL WKT Raster driver during the summer of 2009 will be working for at least one year on WKT Raster. Jorge is working for DEIMOS Space, a Spanish aerospace company leading the Espana virtual project. Jorge's superior, Miguel Lizondo, confirmed that Jorge would be devoting most of his time to WKT Raster in the coming year. This commitment should normally be extended for a second year afterward.

Jorge will follow the planned roadmap and will be the main developper for the coming year. Mateuzs Loskot will continue contribute his spare time to the project and Pierre Racine will help Jorge with the specifications and the general management of the project.

Welcome (back) Jorge!

October 16, 2009
PostGIS WKT Raster at Geomatique 2009 in Montréal!
Pierre Racine will present WKT Raster at Geomatique 2009 in Montréal on October 20. We hope we can get more people interested by the project! See the presentation (PDF)!

June 04, 2009
A prototype GDAL driver to WKT Raster implemented this summer!
Thanks to Mateusz Loskot, who proposed the Google Summer of Code project and Jorge Arevalo the student who was selected to implement it.

Welcome to the PostGIS Raster project home page!

PostGIS Raster is an ongoing project aiming at developing raster support in PostGIS. It is a new project very different from the previous PGRaster project and also very different from Oracle Spatial GeoRaster.

The goal of PostGIS Raster is to implement the RASTER type as much as possible like the GEOMETRY type is implemented in PostGIS and to offer a single set of overlay SQL functions (like ST_Intersects) operating seamlessly on vector and raster coverages.

Installation

  • Linux - You will have to compile PostGIS Raster following the instructions in the Development Info section below.
  • Windows Binaries - If you are running PostGIS on Windows, you can find fairly recent binaries of PostGIS Raster in the Windows Experimental Builds section along with binaries of the most recent PostGIS. These are for PostgreSQL 8.3, 8.4, upcoming 9.0. Note that development on the standalone wktraster project deployable on PostGIS 1.3-1.5 has stopped and all future versions and bug fixes of raster support will be packaged in the PostGIS 2.0 builds.
  • Mac OSX Binaries - If you are running PostGIS on Mac OSX leopard or Snow Leopard, you can find fairly recent binaries of PostGIS and PostGIS Raster at KyngChaos PostgreSQL GIS packages include PostgreSQL 8.4, PostGIS 1.5, PostGIS Raster, and pgRouting.

Documentation

  • Presentations

    • Introducing PostGIS WKT Raster: Seamless Raster/Vector Operations in a Spatial Database - FOSS4G 2010, Barcelona, Spain, September 2010. PDF
    • PostGIS WKT Raster. An Open Source alternative to Oracle GeoRaster - FOSS4G 2010, Barcelona, Spain, September 2010. PDF
    • Introduction to WKT Raster - Geomatique 2009, Montréal, October 2009. PDF
    • Original Project Presentation - rationale, examples and preliminary specifications: PPT, PDF (v1.0)

Development Info

  • Planning

    • With PostGIS 2.0: Spring 2011.
    • Look at the planning page for a detailed schedule and to know how to contribute.

Displaying PostGIS rasters

There are some options to display rasters stored in PostGIS.

  • OpenJump - OpenJump will not display raster directly but a vectorization of the raster. Use a query like the following in the "Layer->Execute Query" dialog:
SELECT ST_AsBinary((ST_DumpAsPolygons(rast)).geom), (ST_DumpAsPolygons(rast)).val
FROM rastertable

More Info

For more details and examples of application using PostGIS Raster:

  • PostGIS Raster has been designed following a thorough analysis of the numerous discussions about raster integration in PostGIS over the recent years. You can find most of the post to the PostGIS-users group related to raster integration in this page.

Overview of Planned PostGIS Raster Features

PostGIS Raster...

...is as simple as PostGIS...

  • one table = one raster coverage (like a vector coverage)
  • one row = one tile or one raster object (like a vector coverage where one row = one geometry)
  • only one new type: RASTER (like the PostGIS GEOMETRY type)
  • each raster tile has a pixel size, a width and a height, a variable number of band, a pixel type per band and a nodata value per band. Everything essential to do base raster GIS operations.

...is an extension of PostGIS to be installed separately

  • merge with PostGIS might occur in the future...

...has an import/export mechanism similar to shp2pgsql

  • raster2pgsql and pgsql2raster utilities allowing import/export of a single raster or a batch of raster into a tiled coverage.

...allows easy conversion from/to geometry/raster...

  • ST_DumpToPolygons(raster) -> geometry set
  • ST_AsRaster(geometry, pixelsize) -> raster

...implements base GIS raster operations available in most GIS...

  • ST_Resample(raster, pixelsize, method) -> raster
  • ST_Clip(raster|geometry,geometry) -> same type as first argument
  • ST_Reclass(raster|geometry,string) -> same type as first argument
  • ST_MapAlgebra(raster|geometry, raster), mathematical expression, "raster"|"geometry") -> raster/geometry
  • etc...)

...introduces raster/geometry seamless geometry constructors...

  • so you don't have to bother whether the layers are in raster or vector form when using analysis functions.
  • ST_Intersection(raster|geometry, raster|geometry, "raster"|"geometry") -> raster/geometry
  • ST_Union(raster|geometry, raster|geometry, "raster"|"geometry") -> raster/geometry
  • ST_Accum(raster set|geometry set, "raster"|"geometry") -> raster/geometry
  • ST_Transform(raster|geometry, SRID) -> same type as input
  • etc...

...and seamless geometry operators...

  • ST_Intersects(raster|geometry, raster|geometry) -> boolean
  • ST_Contains(raster|geometry A, raster|geometry B) -> boolean
  • etc...

...allows raster storage INSIDE the database (as WKB)...

  • for efficient overlay analysis operations between vector and raster layers...

...or OUTSIDE the database (as JPEG or TIFF)...

  • so desktop and web applications can quickly access and load raster tiles and nevertheless benefits from the powerful PostGIS GiST spatial index. Every PostGIS Raster SQL functions working with in-db raster tiles work seamlessly with out-db raster tiles.

...introduces the concept of raster objects...

  • geographic features are stored as variable size raster tiles instead of polygons.
  • allows vector to raster conversion without lost of information.

...is much more simple than PGRaster and Oracle GeoRaster! PostGIS Raster supports...

  • only one type (instead of two in Oracle Spatial: SDO_GEORASTER & SDO_RASTER). In PostGIS Raster there are no differences between rasters and tiles: a tile is a raster and a raster is a tile. i.e. one row = one tile = one raster; one table = one raster coverage.
  • no metadata (like PostGIS)
  • no masks (you can create a mask as a band)
  • no multiple dimensions (only two: x, y). Not to be confused with bands; PostGIS Raster DO supports multiband raster...
  • no pyramids (reduced resolution coverages can be stored as a separate layer)

What do people think about PostGIS Raster?

Paul Ramsey (founder of PostGIS):

This proposal is better than any I have seen, addresses solving problems that if solved will provide actual new functionality and benefit to users, and clearly you've thought this through over some time

Regina Obe (coauthor of PostGIS in Action):

The functions PostGIS WKT Raster proposes look pretty cool actually and my vision of the benefits of storing raster in the database are covered in it

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