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| ==What Marble is all about==
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| This page is a copy of
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| http://websvn.kde.org/trunk/KDE/kdeedu/marble/MANIFESTO.txt?revision=676415&view=markup
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| ===MARBLE - MANIFESTO===
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| ====Principles and intentions of the Marble Project====
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| v.0.3.2, April 12th, 2007
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| Virtual Globes have existed since decades already and have been
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| subject of numerous papers in scientific research. Although many of
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| them had been available for personal computers they only recently
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| gained the awareness of public interest: Google Earth suddenly allowed
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| people to spot their houses' roofs free of charge from high above and
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| enabled them in combination with Google Maps to show their Google
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| Search Queries referenced on a geographical map. Almost instantly
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| Google Earth had become the "industry leader" among virtual globes
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| that others had to measure up to [1].
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| ====Why Marble?====
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| Today there exist numerous virtual globes and the market has embraced
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| strong contenders such as Google Earth/Maps, MS Virtual Earth 3D and
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| NASA WorldWind [2]. A new virtual globe project must be able to offer
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| strong selling points and has got to focus on those without
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| compromises. Otherwise it simply won't gain public relevance.
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| "Where?" is a pretty basic question that computer users have got to
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| ask and answer quite often - no matter what they are working on. The
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| free desktop has been advancing since years already. And while
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| there's a pretty large amount of free software GIS ("Geographical
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| Information System") applications available [3] they are mostly
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| targeted at advanced users who deal with geo data during their daytime
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| jobs or as a matter of enthusiasm. However, most people out there
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| aren't cartographers and don't want to be. These people expect a
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| simple and clean task-oriented interface that adheres to the map
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| layout standards that decades of cartography have developed to improve
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| ease of use of maps.
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| So for casual users there is still missing a fast, flexible, visually
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| pleasing and easy to use map component. For developers, Marble offers
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| a light-weight, fast, cross platform map component that can be used
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| online as well as offline with meaningful results and that don't
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| require proprietary webservices.
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| Marble is meant to become for "geo browsers" what KHTML/WebKit is for
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| web browsers already.
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| From an average user's point of view a map component such as "Marble"
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| should meet the following requirements:
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| =====1. FAST=====
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| To allow instant access and usage as a widget the Marble Widget | |
| should start up instantly and be ready for use within 2-3
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| seconds. So "application" startup time should always be kept as
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| low as possible.
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| Technically this means that the Marble Widget needs to be heavily
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| optimized for start up times and should have a minimal number of
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| dependencies (as an increasing amount of libraries will slow down
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| the application's launch).
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| Most other virtual globes have startup times of 15-30 secs.
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| That's just an eternity to wait for if you just want to look up
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| something.
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| =====2. VISUALLY APPEALING=====
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| The maps drawn by Marble Widget should adhere to visual
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| cartographic standards and should look appealing. Usually people
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| prefer the 3D globe view as it looks more natural, mostly because
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| of minimal distortion and because it looks more "advanced". It
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| should be possible to easily print the maps and to embed them into
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| documents without getting a pixel mess that is hard to decipher.
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| Most other virtual globes don't offer good printing support and
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| the graphical representation most of the time is just limited to
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| satellite views that are often labeled pretty badly. Web based
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| solutions (such as Google Maps) are quite static in their
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| appearance and are limited in terms of possible modification.
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| =====3. EASE OF USE=====
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| Another very important aspect is usability: The feature set should
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| cover the use cases of the primary target user only. 3D flights
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| are pretty exciting for users that want to be entertained.
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| However most users don't need them, don't have the time to
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| experiment with them or don't even discover that feature. So
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| focusing on the top-bottom view exclusively ("2.5D") makes sense
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| for Marble.
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| Maps should be easy to read. In a lot of cases this will mean
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| that the flat projection ("equirectangular projection" / "plate
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| carrée") is more convenient (e.g. in a timezone chooser dialog).
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| I personally consider Google Earth's interface too complex for
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| most users we are aiming for. Google Maps on the other hand seems
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| too simple to me and also has a slight annoyance factor due to its
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| web based nature.
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| =====4. MINIMAL HARDWARE/SOFTWARE REQUIREMENTS=====
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| The Marble Widget should work at usable speed out of the box on
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| all possible hardware the desktop environment is running on. It
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| should always show exactly the same output independent of the
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| hardware. During installation modifications to the system should
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| stay as low as possible.
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| This is an important point as people will simply neglect a
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| solution if it's too painful to install or results in other
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| unnecessary challenges during configuration. Unfortunately many,
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| if not most, computer systems out there don't offer decent 3D
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| hardware acceleration for graphics. So the solution we are aiming
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| for should not depend on 3D hardware acceleration, although we
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| certainly might want to offer solutions such as an OpenGL backend
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| as an option. Also the amount of software needed to install the
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| map component should stay as low as possible (see 1.) ).
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| =====5. OFFLINE USAGE=====
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| The Marble Widget should offer a minimal data set that is
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| specifically edited and compiled for offline usage. This is
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| especially useful in countries where internet access is restricted
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| or expensive. Online usage should cover incremental downloading
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| of texture tiles, vector data (e.g. OpenStreetMap) and wikipedia
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| articles.
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| Concerning offline geographical data Marble intends to deliver the
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| "biggest bang for the byte" and provide as much high quality
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| information per byte as possible.
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| For all information that goes beyond map labels ("Marble Almanac")
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| we have started cooperation with the Wikipedia Offline Reader
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| Project.
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| =====6. FREE SOFTWARE & OPEN STANDARDS=====
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| The Marble Widget is free software and should use a small set of
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| open standards for communication with other applications at
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| runtime and to save data to the storage medium. The open KML file
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| format[4] used by Google Earth is probably the most popular file
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| format these days to geo reference data. Through "feeding" KML
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| streams to the map component, applications are offered a simple
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| "programming" interface to control the map's appearance and
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| behaviour. All Information displayed on the map widget should be
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| covered by free licenses using sources such as NASA or
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| OpenStreetMap.
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| Many other virtual globes are proprietary and are using commercial
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| geo data that is considered "non-free" (as it isn't freely
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| redistributable).
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| ====The Marble Universe====
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| Apart from the Marble Widget (which is implemented using the Qt4.2
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| library only) there are other planned member components of the Marble
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| universe:
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| =====1. Marble Desktop Globe=====
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| KDE 4 application for KDE-EDU: This "reference" application is
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| meant to show off much of Marble's full potential. At the current
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| point of time it's the next logical step as educational
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| applications don't need to cover the data in full detail to be
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| useful. Once it reaches maturity the Marble backend could be
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| moved into a more central place, e.g. kdelibs/base.
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| =====2. Marble Widget=====
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| Can be used in different applications like KStars, KControl,
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| DigiKam, KGeography, Kopete, Addressbook, Risk-Game, KWorldClock,
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| Traceroute, Plasma Weather Applet, and so on. Depending on the use case
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| it can have different appearances:
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| * "normal" widget
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| * selection dialog
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| * developer mode
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| =====3. Marble Framework=====
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| A framework of geo services for the desktop. This should cover a
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| "position provider" backend like GPS, hostip.info, track turtle,
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| and information services ( "Marble Almanac" ).
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| Torsten Rahn
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| ====References====
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| [1] as an interesting read see the discussion section at http://www.earthslot.org/vgconference/VGconference_results.php
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| [2] for a nice introduction into virtual globes and a non-comprehensive list of them see the article at Wikipedia http://en.wikipedia.org/wiki/Virtual_Globe
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| [3] www.freegis.org provides a nice software overview on Free Geographic Information Systems
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| [4] KML 2.1 Reference available at: http://earth.google.com/kml/kml_tags_21.html
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