OSGeo - User contributions [en]

User:Luisw

2009-06-18T19:19:27Z

Wiki-Luisw:

Some bits of me.

I've being software developer for more than 20 years now. Some languages (C, python, Java, some others ...), Some environments (Ancient UNIX, Linux, Windows ... some others). I like interoperability, I like portability, and for sure, I like to develop software!

I started to do GIS programming on 2004, entering on gvSIG project (before than the name itself, wich I created because they have no named the creature and OpenGIS seemed too general.)

Related OSGeo website: [http://wiki.osgeo.org/index.php/Espa%C3%B1ol Español]

Now a days I'm mentoring an [http://socghop.appspot.com/ GSOC] project [http://socghop.appspot.com/student_project/show/google/gsoc2009/osgeo/t124023167228 WMS Tiling Cache support in gvSIG]

An since April 14th, 2009 I'm working for Sigrid S.L. [http://www.stereowebmap.com Stereowebmap] [http://www.sigrid.es Sigrid]

email: cresques at gmail dot com 
skype: cresques

2007-03-10T14:25:58Z

Wiki-Luisw: /* Algunos asistentes a esta reunión */

===I Jornadas SIG Libre===
Del 5 al 7 de marzo de 2007 se celebró en Girona (España), una [http://www.sigte.udg.es/jornadassiglibre/ estupenda conferencia] sobre software de gis libre, organizada de una manera modélica por el [http://www.sigte.udg.es/ Servicio de SIG y Teleledetección (SIGTE)] de la Universidad de Girona.

=== Reunión sobre OSGeo Local Chapter===

En la tarde del martes, y como muestra de los efectos sinergicos de este tipo de congresos, se improvisó la convocatoria para el dia siguiente a las 14:30 (durante la pausa de la comida), de una reunión exploratoria para la constitución del capítulo local español de OSGeo. Hasta ese momento, en España las comunidades de interes en esta materia, bien en el uso como en el desarrollo, estaban agrupadas al rededor de su herramienta, o bien poco conectadas, con lo que parecía que la necesidad estaba creada. Por otra parte, el que se tratara de la primera vez en España que se convocaba un congreso sobre GIS libre, de una manera tan abierta y planificada hacía de esta una gran oportunidad.

De esa reunión entre [[User:ominiverdi|Lorenzo Becchi]] y [[User:Luisw|Luis W. Sevilla]] salió la convocatoria en papel, el planteamiento inicial, y la búsqueda (posteriormente confirmada) del consentimiento y apoyo de SIGTE (En las personas de [[User:Lluís|Lluís Vicens]] e Irene Compte) para la misma. A SIGTE les pareció una idea que se enmarcaba perfectamente dentro de los objetivos de las jornadas, imprimieron y colgaron unos carteles, y cedieron la sala 'petita' del auditorio para la misma.

A la reunión acudieron en principio algo más de una docena y media de personas, a las que se fueron sumando otras hasta totalizar 30 (¡sobre 120 asistentes!). Lorenzo Becchi, que venía de estar un año y medio participando en la creación del grupo italiano de [http://www.gfoss.it foss4g (GFOSS.it)], y que estaba al tanto del funcionamiento de OSGeo realizó una muy esclarecedora explicación de los objetivos y beneficios de OSGeo.

A lo largo de la sesión (de unos 45 minutos de duración), se mostró interés por parte de miembros de la comunidad de GRASS, gvSIG, Monogis, geoServer, ka-map, de empresas, universidades y administraciones públicas para la formación de este capítulo, así como la voluntad de realizar colaboraciones en un contexto multicomunidad. Una de las primeras decisiones fue que se creara '''el capítulo de idioma español, no solamente de España'''.

Se trató el tema de crear un buen '''libro de GIS en español''', libre, así como de la posibilidad de crear material docente de uso conjunto, realización de traducciones y otras iniciativas.

Finalmente los 29 asistentes apuntaron su nombre y email para que Lorenzo, en su papel de facilitador del grupo, solicitase a OSGeo la lista de correo y se la notificase a todos.

También se acordó que una vez constituida la lista se anunciaría en los máximos foros posibles, como por ejemplo la lista SIG de REDIRIS, las listas de las comunidades de usuarios o el portal de noticias [http://www.meneame.net Meneame].

La [[Español| página del procedimiento para el Capitulo Español de OSGeo]]

===Algunos asistentes a esta reunión===
* [[User:ominiverdi|Lorenzo Becchi]] (ominiverdi, ka-map)
* [[User:Luisw|Luis W. Sevilla]] (CIT-GV, gvSIG)
* [[User:Lluís|Lluís Vicens]] (SIGTE-UdG)
* [[User:Alvaro|Alvaro Anguix]] (IVER, gvSIG)
* Gabriel Roldan (AXIOS, geoserver, geotools)
* Victor Olaya (UNEX, sextante, saga, gvSIG)
* [[User:Jcfernan|Juan Carlos Gimenez]] (UNEX, sextante, saga, gvSIG)
* Agustin Diez (UV, grass)
* [[User:Rantolin|Roberto Antolín]] (UMilan, grass)
* [[User:Jsanz|Jorge Gaspar Sanz]] (Prodevelop, gvSIG)
* [[User:MMontesinos|Miguel Montesinos]] (Prodevelop, gvSIG)
* [[User:Jacarma|Javier Carrasco]] (Prodevelop, gvSIG)
* Francisco Alonso (UMurcia, grass)
* [[User:Mpaul42|Michael Paul]] (monogis)
* Angel Montalban (Genasys)
* [[User:mdelacalle|Manuel de la Calle]] (fomex, gvSIG)

Meeting Girona

2007-03-10T14:25:30Z

Wiki-Luisw: /* Algunos asistentes a esta reunión */

Meeting Girona

2007-03-10T14:24:51Z

Wiki-Luisw:

2007-03-10T14:24:28Z

Wiki-Luisw:

==Introducción (es)==

En dos eventos distintos se ha manifestado la intención de crear un Capitulo Local OSGeo de idioma Español.
El primero tuvo lugar [http://wiki.osgeo.org/index.php/Resultados_del_Tutorial_ISSTOCAM_WebGIS ISSTOCAM WebGIS Meeting] en Ostende, Belgica (resultando en la página [[Sudamerica]]) y el segundo han sido las [[Meeting_Girona| I Jornadas de SIG Libre]] en Girona, España.
Se trata de un muy buen comienzo para juntar esfuerzos y crear una comunidad muy amplia dentro de OSGeo.

==Introduction (en)==
Two different meetings have manifested the intention to create a Spanish language OSGeo local chapter.
One is the [http://wiki.osgeo.org/index.php/Resultados_del_Tutorial_ISSTOCAM_WebGIS ISSTOCAM WebGIS Meeting] in Oostende Belgium (also giving birth to the page [[Sudamerica]]),
and the other is the [http://www.sigte.udg.es/jornadassiglibre/ first Spanish meeting about foss4g] in Girona Spain.
This is a very good starting point to join efforts and create a widespread community inside OSGeo.

==Lista de Interesados==
Por favor leed [[Español#Chapter_Roles|el rol del Local Chapter]] y sus [[Español#Chapter_Responsibilities|Responsabilidades]] antes de ajuntar el propio nombre.

* [[User:ominiverdi|Lorenzo Becchi]]
* [[User:Arnulf Christl|Arnulf Christl]]
* [[User:Luisw|Luis W. Sevilla]]
* [[User:Jsanz|Jorge Gaspar Sanz]]
* [[User:Alvaro|Alvaro Anguix Alfaro]]
* [[User:Rantolin|Roberto Antolín Sánchez]]
* [[User:jacarma|Javier Carrasco Marimón]]
* [[User:MMontesinos|Miguel Montesinos]]
* [[User:mpaul42|Michael Paul]]
* [[User:Koen Verbist|Koen Verbist]]
* [[User:Lluís|Lluís Vicens]]
* [[User:jcfernan|Juan Carlos Giménez Fernández]]
* [[User:FranciscoPalm|Francisco Palm]]
* [[User:mdelacalle|Manuel de la Calle]]
* añadete tu mismo

==Lista de correo==
[[User:ominiverdi|Lorenzo]] ya ha puesto en marcha la lista de correo '''Spanish''' para OSGeo:

[http://lists.osgeo.org/mailman/listinfo/spanish http://lists.osgeo.org/mailman/listinfo/spanish]

==Difusión del proyecto==
Listado de medios en los que sería interesante que se anunciara el inicio del proyecto.Indicar responsable de avisar al medio y conforme se vayan publicando las reseñas se pueden ir <s>tachando</s>.
=== Newsletters ===
* [[Newsletter]]
=== Listas de Correo ===
* <s>Lista SIG RedIRIS</s>
* Discussion List de OSGeo

=== Foros ===
=== Sitios de noticias ===

* [http://www.nosolosig.com/ Nosolosig] (encargado de avisar: Alvaro Anguix)
* [http://www.cartesia.org/ Cartesia] (encargado de avisar: Alvaro Anguix)
* <s>[http://www.libroblanco.com/html/index.php Libro Blanco del Software Libre]</s>

=== Revistas ===
* [http://geofocus.rediris.es/ geofocus]
* [http://www.mappinginteractivo.com/ Mapping Interactivo]
* [http://www.geoconnexion.com/ Geonnexion International Magazine]
* [http://www.gim-international.com/ GIM International]
===Blogs===
* <s>[http://geomaticblog.net/ geomaticblog]</s>
* <s>[http://blog.ominiverdi.org/ Ominiverdi's Blog]</s>
* <s>[http://www.alpoma.net/carto/ La Cartoteca]</s>

== Roles del Capítulo (es) ==

El software Open Source ha demostrado ser un entorno para construir software más fuerte mediante la colaboración global. La Fundación Software Abierto Geoespacial, a partir de ahora OSGeo, ha sido creada para apoyar y construir el software geoespacial de más alta calidad.

La meta de OSGeo es aumentar el uso de proyectos OSGeo globalmente promoviendo una fuerte asociación localizada y la presencia en diferentes dominios geográficos y lingüisticos. Además de ser una fuerte voz local para OSGeo, algunas de las principales tareas con las que esta asociación local de OSGeo puede enriquecer y mejorar las iniciativas geoespaciales globales pueden ser:

* Proporcionar soporte y oportunidades de trabajo a los miembros a través de la red
* Internacionalización y localización de software
* Desarrollar prototipos de aplicaciones para demostrar las capacidades del software abierto geoespacial a audiencias locales o regionales
* Empaquetado y personalización para las necesidades locales y regionales
* Educación, soporte y desarrollo de contenidos de aprendizaje en lenguaje español
* Soporte de estándares abiertos y acceso abierto a datos geoespaciales de la región
* Promover OSGeo y mejorar su visibilidad en varios foros

Estas actividades complementarían y fortalecerían los esfuerzos de OSGeo en aumentar el conocimiento acerca de soluciones geoespaciales de código abierto estimulando su adopción en la educación, en la industria, en el gobierno y organizaciones sin ánimo de lucro y en variados dominios geográficos y lingüisticos.

== Chapter Roles (en) ==

Open Source software has come to be a proven environment for building stronger software through open global collaboration. The Open Source Geospatial Foundation, hereafter referred to as OSGeo, has been created to support and build the highest-quality geospatial software.

The OSGeo's goal is to promote the use OSGeo projects globally by fostering strong localized OSGeo partnership and presence in different geographic and linguistic domains. Apart from being a strong local voice for the OSGeo, some of the major tasks whereby localized OSGeo partnership and presence could enrich and enhance global geospatial initiatives would be;

* Provide member networking opportunities for support and job opportunities
* Software Internationalization and Localization
* Development of prototype applications to demonstrate Open Source geospatial capabilities to local and regional audiences
* Software Packaging and Customization for local and regional needs
* Training, Support and Development of e-Learning Contents in local languages
* Support Open standards and Open access to geospatial data in region
* Promoting OSGeo and enhancing visibility in various forums

The above activities would complement and strengthen the efforts of OSGeo in increasing awareness about available Open Source Geospatial solutions and stimulating adoption in education, industry, government and non-profit organizations in various geographic and linguistic domains.

== Responsabilidades del Capítulo (es) ==
OSGeo no diferencia entre un grupo geográfico y uno lingüístico y estimula la organización autónoma de forma similar a los ''Grupos de Usuarios'' o ''Grupos de Interés Especial'' en otros proyectos ''Open Source''. Los ''Grupos de Usuarios'' o los ''Grupos de Interés Especial'' no representan formalmente a OSGeo pero pueden aprovechar algunos de los servicios como el uso del Wiki de OSGeo. El ''Capítulo Español'' ofrece una estructura formal de organización autónoma basada en una pocas directrices listadas a continuación:
* El ''Capítulo Español'' oficialmente representa OSGeo y es formalmente reconocido como un proyecto de OSGeo.
* El ''Capítulo Español'' debe apoyar las misiones y objetivos de OSGeo.
* El ''Capítulo Español'' debe mantener encuentros regulares (al menos uno anual) y proporcionar un informe anual sobre las actividades del mismo al Comité de Dirección (?) de OSGeo.
* El ''Capítulo Español'' no dispondrá de ningún compromiso financiero de o en nombre de OSGeo. De igual forma, OSGeo no proporcionará ningún presupuesto al ''Capítulo Español''.
* El ''Capítulo Español'' debe esforzarse en su relación con las organizaciones para conseguir la participación y el soporte para OSGeo.
* OSGeo se reserva el derecho a terminar su relación con el ''Capítulo Español'' si tiene razones para creer que las actividades del ''Capítulo Español'' son contrarias o en detrimento de la Misión y Objetivos de OSGeo.

== Chapter Responsibilities (en) ==

OSGeo does not differentiate between a geographic or linguistic grouping and strongly encourages self-organization similar to "User Groups" or "Special Interest Groups" in other
Open Source Projects. "User Groups" or "Special Interest Groups" do not formally represent OSGeo but can avail some of the services such as the use of OSGeo Wiki. "OSGeo Chapter" offer
a more formal framework for self-organization based on a few simple guidelines listed below;

* “OSGeo Chapter” officially represents OSGeo and is formally recognized as OSGeo Project.
* “OSGeo Chapter” must support the OSGeo Mission and Objectives of OSGeo.
* “OSGeo Chapter” must hold regular meetings (at least annual) and provide annual report of activities to chapter membership and OSGeo Board.
* “OSGeo Chapter” will not entail any financial commitment from or on-behalf of OSGeo. OSGeo will also not provide any budget assistance to the “OSGeo Chapter”.
* “OSGeo Chapter” is encouraged develop and maintain “Directory Listing” of companies, people, universities and organizations involved with or using OSGeo projects.
* “OSGeo Chapter” must strive at networking with organizations to enlist participation and support for OSGeo.
* OSGeo reserves the right to terminate its relation with an “OSGeo Chapter” if OSGeo has reasons to believe that the activities of the “OSGeo Chapter” are contrary or detrimental to the Mission and Objectives of OSGeo.

== Ventajas del Capítulo (es) ==
* Se permite al ''Capítulo Español'' el uso del logotipo de OSGeo y otros recursos de imagen corporativa (???) para promocionar la Misión y Objetivos de OSGeo.
* OSGeo proporcionará la infraestructura necesaria para promocionar la comunicación y visibilidad del ''Capítulo Español''. La infraestructura incluye una lista de correo, hospedaje para páginas wiki y servicio de dominio para el ''Capítulo Español''.

== Chapter Benefits (en) ==

* “OSGeo Chapter” is permitted to use OSGeo Logo and other branded resources for promoting the Mission and Objectives of OSGeo.
* OSGeo will provide necessary infrastructure to promote communication and visibility of “OSGeo Chapter”. The infrastructure will include mailing list, hosting of wiki pages, domain service for “OSGeo Chapter”.

== Chapter Formation ==

In order to form a chapter, the following steps should be taken:
# "OSGeo Chapter" should self-organize (for instance in the OSGeo wiki, via OSGeo mailing list, etc), seeking to determine if a critical mass of interest exists to justify a chapter.
##DONE: [http://lists.osgeo.org/mailman/listinfo/spanish Mailing List] and this page. Hope to have soon a dedicated Wiki and a Web Site.
# "OSGeo Chapter" should prepare a mission and objectives indicating the scope of the planned chapter (geographic or linquistic extent for instance).
##DONE: The mission is to sustain and spread OSGeo principles in Spanish Language without country borders limitations.
# “OSGeo Chapter” should propose an official representative to liaise with the OSGeo Board. If accepted by the board, the representative will be an officer of OSGeo.TODO
# “OSGeo Chapter” should submit an official expression of interest to form a chapter to the OSGeo board, listing initial members, mission, representative and other supporting information.TODO
# The OSGeo board shall then consider passing a motion forming the chapter, and designating the liason officer.TODO

In considering the formation of new OSGeo chapters, the board will consider issues including:
* Does the mandate (geographically or linguistically) conflict with other existing chapters or chapters-in-formation?
* Does the chapter appear to have sufficient interest to justify official formation?
* Does the chapter appear to be open to broad membership, and representative of the target geographic or linguistic community? (eg. if a chapter had the objective to cover all Spanish speakers, it would be inappropriate if the only interest demonstrated was from one country)

[[Category:Local Chapters]]

2007-03-09T16:36:32Z

Wiki-Luisw:

2007-03-08T11:15:20Z

Wiki-Luisw:

==Introducción (es)==

Dos distintos eventos han manifestado la intención de crear un Capitulo Local OSGEO de idioma Español.
El primo evento ha sido [http://wiki.osgeo.org/index.php/Resultados_del_Tutorial_ISSTOCAM_WebGIS| ISSTOCAM WebGIS|Meeting] in Ostenda Belgica y el segundo han sido las [http://www.sigte.udg.es/jornadassiglibre/|I Jornadas de SIG Libre] in Girona, España.
Esto significa un comienzo muy bueno para juntar esfuerzos y crear una cumunidad muy amplia adentro de OSGEO.

==Introduction (en)==
Two different meetings have manifested the intention to create a Spanish language OSGEO local chapter.
One is the [http://wiki.osgeo.org/index.php/Resultados_del_Tutorial_ISSTOCAM_WebGIS| ISSTOCAM WebGIS|Meeting] in Oostende Belgium,
and the other is the [http://www.sigte.udg.es/jornadassiglibre/|first Spanish meeting about foss4g] in Girona Spain.
This is a very good starting point to join efforts and create a widespread community inside OSGEO.

==Lista de Interesados==
* [[User:ominiverdi|Lorenzo Becchi]]
* [[User:Arnulf Christl|Arnulf Christl]]
* [[User:Luisw|Luis W. Sevilla]]

== Chapter Roles ==

Open Source software has come to be a proven environment for building stronger software through open global collaboration. The Open Source Geospatial Foundation, hereafter referred to as OSGeo, has been created to support and build the highest-quality geospatial software.

The OSGeo's goal is to promote the use OSGeo projects globally by fostering strong localized OSGeo partnership and presence in different geographic and linguistic domains. Apart from being a strong local voice for the OSGeo, some of the major tasks whereby localized OSGeo partnership and presence could enrich and enhance global geospatial initiatives would be;

* Provide member networking opportunities for support and job opportunities
* Software Internationalization and Localization
* Development of prototype applications to demonstrate Open Source geospatial capabilities to local and regional audiences
* Software Packaging and Customization for local and regional needs
* Training, Support and Development of e-Learning Contents in local languages
* Support Open standards and Open access to geospatial data in region
* Promoting OSGeo and enhancing visibility in various forums

The above activities would complement and strengthen the efforts of OSGeo in increasing awareness about available Open Source Geospatial solutions and stimulating adoption in education, industry, government and non-profit organizations in various geographic and linguistic domains.

== Chapter Responsibilities ==

OSGeo does not differentiate between a geographic or linguistic grouping and strongly encourages self-organization similar to "User Groups" or "Special Interest Groups" in other
Open Source Projects. "User Groups" or "Special Interest Groups" do not formally represent OSGeo but can avail some of the services such as the use of OSGeo Wiki. "OSGeo Chapter" offer
a more formal framework for self-organization based on a few simple guidelines listed below;

* “OSGeo Chapter” officially represents OSGeo and is formally recognized as OSGeo Project.
* “OSGeo Chapter” must support the OSGeo Mission and Objectives of OSGeo.
* “OSGeo Chapter” must hold regular meetings (at least annual) and provide annual report of activities to chapter membership and OSGeo Board.
* “OSGeo Chapter” will not entail any financial commitment from or on-behalf of OSGeo. OSGeo will also not provide any budget assistance to the “OSGeo Chapter”.
* “OSGeo Chapter” is encouraged develop and maintain “Directory Listing” of companies, people, universities and organizations involved with or using OSGeo projects.
* “OSGeo Chapter” must strive at networking with organizations to enlist participation and support for OSGeo.
* OSGeo reserves the right to terminate its relation with an “OSGeo Chapter” if OSGeo has reasons to believe that the activities of the “OSGeo Chapter” are contrary or detrimental to the Mission and Objectives of OSGeo.

== Chapter Benefits ==

* “OSGeo Chapter” is permitted to use OSGeo Logo and other branded resources for promoting the Mission and Objectives of OSGeo.
* OSGeo will provide necessary infrastructure to promote communication and visibility of “OSGeo Chapter”. The infrastructure will include mailing list, hosting of wiki pages, domain service for “OSGeo Chapter”.

== Chapter Formation ==

In order to form a chapter, the following steps should be taken:
# "OSGeo Chapter" should self-organize (for instance in the OSGeo wiki, via OSGeo mailing list, etc), seeking to determine if a critical mass of interest exists to justify a chapter.TODO
# "OSGeo Chapter" should prepare a mission and objectives indicating the scope of the planned chapter (geographic or linquistic extent for instance).TODO
# “OSGeo Chapter” should propose an official representative to liaise with the OSGeo Board. If accepted by the board, the representative will be an officer of OSGeo.TODO
# “OSGeo Chapter” should submit an official expression of interest to form a chapter to the OSGeo board, listing initial members, mission, representative and other supporting information.TODO
# The OSGeo board shall then consider passing a motion forming the chapter, and designating the liason officer.TODO

In considering the formation of new OSGeo chapters, the board will consider issues including:
* Does the mandate (geographically or linguistically) conflict with other existing chapters or chapters-in-formation?
* Does the chapter appear to have sufficient interest to justify official formation?
* Does the chapter appear to be open to broad membership, and representative of the target geographic or linguistic community? (eg. if a chapter had the objective to cover all Spanish speakers, it would be inappropriate if the only interest demonstrated was from one country)

[[Category:Local Chapters]]

WMS Tile Caching

2006-10-19T10:27:46Z

Wiki-Luisw: /* Interested Parties */

== Goal ==

The goal of a '''WMS Tile Caching''' proposal, perhaps ''WMS-C'' for short, is to find a way to optimize the delivery of map imagery across the Internet. The proposal needs to offer ideally some means by which map clients can fetch tiles from existing servers, in such a way that the images can be cached on the server, or at an intermediate location, or even be completely pre-generated, if desired. Further, the proposal needs to offer a way of advertising that a cached tile set is available for a given layer from a particular WMS or WMS proxy. The proposal should leverage the existing investment in OGC-compliant WMS servers on the 'Net.

The two main questions to be addressed are:
# How does a server advertise its cacheable image tiles?
# How does a client request possibly cached image tiles?

== Proposal ==

=== WMS-C as WMS Profile ===

One approach to take might be to define ''WMS-C'' (as in ''Web Mapping Service - Cached'') as a constrained profile of [http://www.opengeospatial.org/docs/01-068r2.pdf OGC WMS] that permits servers to optimize their image generation, and allows tiles to be cached at intermediate points. A WMS-C service would likely only deliver images for bounding boxes aligned to a given rectangular origin and grid, and only at particular scale levels.

The basic idea is that, unlike with WMS, two different requests for a given WMS-C tile should form the exact same HTTP GET request. This invites several constraints on WMS ''GetMap'' requests:

# Minimal query string arguments (i.e. no optional arguments permitted, versus §7.2)
# Fixed query string argument ordering and case (versus §6.4.1; q.v. also §7.2.2, Table 8)
# Fixed range of possible bounding boxes, computed from the WMS-C profile parameters
# Fixed precision on bounding box values (clarifying §6.5.6)
# Fixed tile size in pixels
# Fixed layer name and/or layer name ordering
# Fixed styling
# Fixed output format

Some means of identifying these constraints programmatically on a per-server basis, a la ''GetCapabilities'' might be desirable. From the table below, it appears that minimum/maximum scale (and scale quantization factor, which should probably never be other than 2) are the only suggested tiling regime parameters that would be difficult to directly express in a WMS GetCapabilities document. Is there some existing way to add custom parameters to a GetCapabilities declaration?

Note that the ''LAYERS'', ''STYLES'', ''SRS'', ''HEIGHT'', ''WIDTH'', and ''FORMAT'' arguments to a ''GetMap'' request would become fixed for a particular WMS-C tiled layer, but the WMS specification would still require the inclusion of these arguments in every WMS-C request (§ 7.2).

A WMS-C proxy or server should be free to return an exception or a redirect, if it receives a WMS request that is not WMS-C compliant, or involves a bounding box that does not correspond to a single tile in the cache.

=== Calculating Valid Tile Extents for a Given Request ===

WMS tile caching implies fixed scale or zoom levels. Typically, each valid scale level would be half that of the next larger scale. It would be worth writing reference code to help developers figure out which tiles they need to load to cover a given bounding box at a given scale.

=== Possible Tile Scheme Parameters ===

{| cellpadding="5" cellspacing="1" border="1"
| '''Parameter''' || '''Default value''' || '''Specifiable in WMS GetCapabilities?'''
|-
| "This service suppports tiling." || ''none'' || ''<KeywordList>'' contains the string 'tiled', perhaps? (§7.1.4.5.3)
|-
| Projection || EPSG:4326 || ''<SRS>''
|-
| Maximal extent || (-180,-90,180,90) || ''<BoundingBox>'' (§7.1.4.5.7)
|-
| Number of horizontal and vertical tiles at the maximal extent || ''none'' || Could be implied by ''<ScaleHint>'' (§7.1.4.5.8, but note that the format is weakly specified)... Alternately, could use ''<DataURL>'' (§7.1.4.5.14)
|-
| Tile size in pixels || some power of 2 || <Layer> attribute ''fixedWidth'', ''fixedHeight'' (§7.1.4.6)
|-
| Minimum scale || ''none'' || ''<ScaleHint>'' or ''<DataURL>'' (see note, above)
|-
| Scale quantization factor || 2 || ''<DataURL>''
|}

----

== Other Considerations ==

* Would non-rectangular tessellations yield more efficient results? If so, which tessellations to consider? Also, are the processing and bandwidth advantages of a non-rectangular tessellation outweighed by the potential implementation complexity?
* Norm Vine rightly points out that a tile request basically boils (or should boil down to) Layer + Zoom Level + Row + Column. Can we define an even simpler method for requesting tiles from servers in the know? How are those capabilities advertised, if not shoehorned into WMS? Note that WorldWind basically already has a mechanism for this. Their tiling requests basically look like:

http://domain.tld/service?L=0&X=1&Y=2
* Like all caching schemes, WMS-C caches would need to be cognizant of expiration. Easy with using the proper HTTP headers. There is a wide range of freshness/staleness, with OpenStreetMap being highly volatile, and Landsat being pretty stable (until the ice caps melt ;).
* Several people (particularly Paul Spencer and Chris Schmidt) have argued that a separate ''GetTile'' request should be used. This topic probably warrants discussion.

== Distributed Caching ==

* A WMS-C standard would permit tile caching through [http://www.coralcdn.org/ Coral]. However, the World Wind community's experience has been that using Coral to serve tiles results in frustratingly high latency.
* Alternately, one could do (distributed) [[Distributed Tile Caching|peer-to-peer tile caching]] optimized specifically for geographic space, which might still suffer the latency issues associated with P2P networks.

== Existing Tiling Schemes ==

* Mikel Maron's description of [http://lists.eogeo.org/pipermail/tiling/2006-March/000017.html OnEarth's LandSat tiling scheme]
* World Wind's LandSat tiling scheme: [http://www.ceteranet.com/nww-tile-struct.pdf PDF], [http://www.worldwindcentral.com/wiki/Making_Layers wiki]
* World Wind ''QuadTileSet'' [http://rafb.net/paste/results/S3I8Zr92.html sample description], [http://forum.worldwind.arc.nasa.gov/lofiversion/index.php?t2965.html forum discussion], [http://rafb.net/paste/results/z2dQKa54.html sample PHP code] to fetch WW tiles for a given WMS GetMap request
* osgPlanet's C++ code for [http://www.remotesensing.org/cgi-bin/cvsweb.cgi/osgPlanet/src/osgPlanet/osgPlanetGridUtility.cpp?rev=HEAD;content-type=text%2Fx-cvsweb-markup tiling the Earth]
* WorldWind Example code for tiling the Earth (needs Proj.4 and GDAL libraries)[http://download.worldwindcentral.com/dstile-0.2.tar.gz DSTile and Tilepack]
* OnEarth's code for intercepting WW requests and converting into WMS requests and caching them [http://www.twobeds.com/upload/userfiles/adamhill/lucians%20code%20-%20cache_1_1.gz?PHPSESSID=f485cf3fd66cd30ad7a4f814a127d2cb from Lucian Plesa]
* Casey Chestnut explains Microsoft Virtual Earth's tiling scheme + code to experiment with the URL's [http://www.brains-n-brawn.com/veWorldWind/]
* GeoOdyssey's [http://www.geodyssey.com/tileshare/index.html TileShare scheme]
* Chuck Stein's [http://www.geongrid.org/workshops/geonvis2005/Presentations/ChuckStein/GeoFusion.ppt GeoFusion presentation] from GEON (warning: PowerPoint)
* [http://globe.sintef.no/documentation/projection.html The Finite Nearly-Conformal Normal Cylindrical Projection] (Aasgaard's map projection)

Note: WW and OnEarth's schemes are pretty much identical, the WW client just allows you to specify arbitrary tile sizes, coverages and number of levels to accomodate a given client.

== Related Projects ==

* [http://www.ossim.org/osgPlanet.html osgPlanet]
* [http://worldwind.arc.nasa.gov/ NASA WorldWind] ([http://www.worldwindcentral.com/wiki/Main_page wiki])
* [http://worldkit.org/ worldKit]
* [http://communitymapbuilder.org/ Community MapBuilder]
* [http://ka-map.maptools.org/ ka-Map!]
* [http://openlayers.org/ OpenLayers]
* other AJAX map clients, presumably

== Interested Parties ==

''Note:'' Interested parties should join the existing low-volume [http://lists.eogeo.org/mailman/listinfo/tiling EOGEO mailing list] dedicated to this topic.

* [[User:SchuylerErle|Schuyler Erle]]
* [[User"Adoyle"|Allan Doyle]]
* [[user"Nhv"|Norman Vine]]
* [[user"Joshli"|Josh Lieberman]]
* [[user"Adamhill"|Adam Hill]]
* [[user"bitner"|David Bitner]]
* [[user:Mikel|Mikel Maron]]
* [[user:mpg|Michael P. Gerlek]]
* [[user:stvn|Steven M. Ottens]]
* [[user:Pagameba|Paul Spencer]]
* [[user:hallkbrdz|Bryan Hall]]
* [[user:tschaub|Tim Schaub]]
* [[user:dmorissette|Daniel Morissette]]
* [[user:dpatton|Dave Patton]]
* [[user:cholmes|Chris Holmes]]
* [[user:pwramsey3|Paul Ramsey]]
* [[user:luisw|Luis W. Sevilla]]
* ''add yourself''

WMS Tile Caching

2006-10-19T10:26:40Z

Wiki-Luisw: /* Interested Parties */

FOSS4G 2006 Tiling BOF

2006-10-19T08:21:12Z

Wiki-Luisw: /* Attendees */

The '''Map Tiling Bird of a Feather (BOF) session''' at FOSS4G 2006 met from 1730 - 1930 on Tue 12 Sep 2006, with the intention of elaborating a way of being able to efficiently tile and cache map images on the web for use in dynamic clients.

== Summary ==

Christopher Schmidt has written up a [http://lists.eogeo.org/pipermail/tiling/2006-September/000050.html summary of the Tiling BOF] on the [http://lists.eogeo.org/mailman/listinfo/tiling EOGEO tiling list]. If you want to find out what we all discussed and agreed on at the BOF, read that summary. The rest of this page is a ridiculous pseudo-transcript with more detail than anyone probably wants.

In the aftermath of the BOF, several of us agreed that we should additionally write up a "Web Tile Service" or GetTile specification ''in addition'' (and based on the work put into) the WMS compatibility recommendation discussed at the BOF.

The pre-amble to the two new standards is being worked as the [[TilingStandard]] page.

== Attendees ==

Some of the attendees are missing surnames or are absent completely. If you were there but not here, please add yourself!

* Steven Ottens
* Lorenzo Becchi
* Andrew Turner
* Paul Spencer
* Justin ?
* Just van den Broecke
* Mike Adair
* Paul Ramsey (voice of reason)
* Andrea Aime
* Brent Owens
* Steve Lime
* Chris Holmes
* Allan Doyle
* Thaijs ?
* Christopher Schmidt
* Schuyler Erle
* Zak James
* Luis W. Sevilla

(and about 20-25 others who showed up later)

== Rough Transcript ==

The following are SchuylerErle's rough notes on the discussion. People are probably misquoted or misattributed. Please take this as a guide only (or fix it, if you were there and remember differently). ;-)

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Allan: WMS profile. "You have to give something up." Backwards compatibility. * Canonical parameter ordering, use to fill up Squid caches. only need to recognize bad requests.

Paul S.: Getting a map is getting from getting a tile that's part of a map, the server has different expectations of behaviors at map/tile edges (labels, line ends). Shouldn't use GetMap; use GetTile instead.

Allan: use vendor specific param "tiling=true"

Paul S.: Squid works great for raster imagery. How to expire stuff from it
dynamically? Use vendor specific "tile_version"?

Allan: How about an out of band "ExpireTile" WMS request?

Paul R.: Corner issues with floating point numbers dictate rules for rounding.

Paul S.: We should have a standard projection and coordinate system and
extents; put other projections in other profiles. One standard is Google
Mercator (whole world fits on one 256x256), the other is EPSG 4326 (two tiles
at zoom 0).

crschmidt: Mercator = EPSG 41001

Paul S.: Leaning on an undersupported EPSG doesn't support backwards
compatibility

Allan/cholmes: Every compliant server will have to support EPSG 4326 for
universal compatibility

Paul S.: The advantage comes from combining tiles from multiple servers

Paul R.: That just leaves cutting the thing up into pieces... How many tiles
do we start with and how do we split them up after that? How do we get them to line up?

Steven: They don't have to line up in the client, the client can line them up.

Paul S.: We just have to choose a standard origin. In ka-Map we use 0,0 in the
projection becomes 0,0 in the tile grid.

Paul R.: That just leaves scale. In 4326 we start at the top because we know
the max extents.

Paul S.: The other option is to start with a scale of 1:1 and double it, rather
than trying to start at the top.

Andrea: In Italy if we don't support the list scales, hmm

crschmidt: why don't we support a list of scales?

sderle: other profiles will have to do that... but we should define a core
profile that specifies something that everyone will have to support. if they
wan to support other profiles as well, they can advertise that.

crschmidt: we need a standard way of publishing that metadata for profiles. if
you have those parameters is calculate how to use the tiles.

Allan: which is an opportunity for new bugs.
sderle: essentially we are trying to do two things, one a subset of the other:
define all the metadata needed to use a tile server, and define a single consistent global profile with default values for each. we should do both.

Paul S.: caching is not really a requirement for this spec, then, so much as
*cacheability*.

Josh: No fixed param ordering. Breaks HTTP.

Paul S.: what about rendering multiple layers into a single tile set?

Paul R.: Doesn't the WMS layer group support that?

allan: it's not part of the spec, but the spec supports thinking of things that
way.

Josh: because layers can be grouped under a single name, the spec should
require only a single name in the layer parameter.

Josh Lieberman: You want a flag that specifies "base layer" versus "overlay"...

sderle: is it the privilege to throw a standard exception if it receives a
request that doesn't match its advertised profiles?

cholmes/Paul S.: Yes.

crschmidt: But it should be okay for a WMS to return an image that doesn't

allan: or just return a standard HTTP error

Raj: it might be better to always return an image

Joshua: The "tiled" GetCapabilities should be "doesn't support"/"supports both"/"only supports tiling"

Paul R.: if it's tiled only, you may have no choice about what you return, so
you get what the web server returns (a 404)

crschmidt: you can return an image as the content of the HTTP error

Josh: say "should but doesn't have to"

Paul S.: in that case the browser will resize it... so the error image size
doesn't matter

Paul S.: what about the canonical image format?

Allan / Raj: PNG

Paul R.: actually so long as the server is consistent it doesn't matter

Steven: for profile #0, use PNG, but it should be part of the profile definition

Paul R.: the server has to pick one

cholmes: I don't want to have to change my GetCapabilities to pick just one

Allan: the cache should live in a different URL and have its own GetCapabilities

cholmes: but what we're trying to do is limit the client, not the server

Steve Lime: if you don't want to change your server, you're going to have to
cache every format it spits out... or limit that at the cache

Paul R.: the global profile is about interoperability... they need to agree on
lots of things, but image file formats is not one of them

generally: format is *not* specified

Paul S.: what about a standard "dots per inch"?

Paul R.: i.e. what does the list of scales mean? if those values are
cartographic scale, you need to specify a formula to calculate it

Allan: I don't care what we do, but don't use the word "scale"... doesn't mean
anything any more

crschmidt: OpenLayers has always used "resolution" i.e. map units per pixel

Allan / Paul S.: we should use that

Allan: how do we deal with other vendor specific parameters? just throw them
out?

Paul S.: is there going to be tiling information in GetCapabilities? want to
see supports tiling=true. can we add fixed vendor specific parameters there?

Jody Garnett: just put it in the OnlineResource response for GetMap

sderle: should also allow WMS to say "my tiled version is over here"

Paul S.: the tiling profile needs to be able to say in GetCapabilities: here's
my magic string -- my list of additional vendor parameters

Jody: and it needs to be called "magic string" also

Luis Seville: GetTile returns tile (X, Y, L)

crschmidt: that needs to be a different spec... everything goes through GetMap

Jody: for version 2, we'll add a GetTile

Josh/Allan: actually a WTS

Paul S.: default tile size should be 256x256

crschmidt: so the maximum resolution per tile is 1.46025

sderle: and zoom level 0 is the whole world

crschmidt: we don't want to render things outside the world, so we need two
tiles at the top level... factor of two zooms okay?

Paul S.: Makes the most sense

Steven: How many zoom levels are we going to get?

Paul S.: Theoretically it's infinite... list it in the GetCapabilities

crschmidt: how many are going to be in that list?

Allan/Paul S.: one. or more.

generally: Creative Commons ShareAlike license

Paul S., Paul R., Raj and Schuyler volunteer to sketch out spec by Sep 29

Paul S.: and let's code an implementation ASAP

Jody: or two

''END OF SESSION''

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