DIGITAL EARTHS A COMPARATIVE OUTLOOK A COMPARATIVE OUTLOOK Web mapping - Process of designing, implementing, generating and delivering maps on the World Wide Web. Web GIS - The idea is that the users are able to access GIS functionality over the internet without having GIS expertise and purchasing expensive GIS software. Architectures of web mapping applications : Server side application Client side application Popular web mapping applications: Google Earth, Microsoft Virtual Earth, Google Maps, Yahoo Maps, Mapquest etc. A 3D software model or representation of the Earth or another world. Serve satellite & aerial imagery. Provides user with ability to freely move around in virtual environment by changing the viewing angle & position. Compared to a conventional globe they have additional capability of representing different views on the Earths surface i.e. geographical features, man-made features or abstract representations of demographic quantities such as population. The first widely publicized virtual globe was Google Earth. Through Application Program Interfaces (API) and eXtensible Markup Language (XML)-based data specifications, developers and advanced users can create new functions & data. Google Earth: satellite & aerial photos dataset (including commercial Digital Globe images ) with international road dataset. Microsoft Windows Live Local Virtual Earth 3D: 3D interface to the Windows Live Local maps and photos, runs inside Internet Explorer and Firefox NASA World Wind: USGS topographic maps and several satellite and aerial image datasets, the first popular virtual globe along with Google Earth. ArcGIS Explorer a lightweight client for ArcGIS Server, supports WMS and many other GIS file formats. Others: SkylineGlobe, EarthSlot and Celestia A virtual globe program - originally called Earth Viewer and was created by Keyhole, Inc. A client side server Internet mapping application Degree of resolution - based on points of interest Most land covered - at least 15 mts resolution. Las Vegas, Nevada and Cambridge, MA - highest resolution at 15 cm. Has DEM data collected by NASA's Shuttle Radar Topography Mission i.e. can view the Grand Canyon or Mt. Everest in 3D Supports managing 3D Geospatial data through Keyhole Markup Language (KML). Images generally current to within 3 years. Place name and road detail vary greatly - most accurate in N. America and Europe. KML is an XML grammar and file format. KML file is processed by GE and Google Maps in a similar way that HTML and XML files are processed by web browsers. Like HTML, KML has a tag-based structure with names and attributes used for specific display purposes. Thus, GE acts as browser of KML files. TILE MANAGEMENT OF DATA : used to provide high resolution satellite data with fast speed. At higher altitude fewer tiles of low resolution used to represent earth and these tiles divide further into sub-tiles of higher resolution as user zooms in to a particular location. CACHE: created on local machine - data for same place not required to be downloaded again i.e. in absence of internet connectivity, cached data can be viewed. AVAILABLE VERSIONS: 1.Google Earth (free) 2.Google Earth Plus (paid): higher speed, real-time GPS tracking, 3.GE Pro (paid): annotations, more tools, import of GIS formats, create movies of virtual tours. 4.Google Earth Enterprise (paid): most powerful, highly customizable has its own GE server including a database with all geo-data & a powerful GE client. Includes services like geo-coding etc. Errors sometimes occur due to technology used to measure height of terrain; eg. tall buildings in Adelaide cause one part of the city to be rendered as a small mountain, when it is in fact flat. Also, elevations below sea level are presented as sea level; i.e. Salton City, California; Death Valley; and the Dead Sea are all listed as 0 ft when Salton City is approx 200 ft; Death Valley is 286 ft; and the Dead Sea is 1,378 ft. The "Measure" function shows that the length of equator is about 40, km, giving an error of 0.112% compared with the actual value of 40, km Earth; For the meridional circumference, it shows a length of about 39, km, also giving an error of 0.112% compared with the actual value of 40, km. The Arctic polar ice caps & waves in the oceans are completely absent from the current version of GE. The geographic North Pole is found hovering over the Arctic Ocean. There is very low resolution coverage of the Antarctic continent (1m resolution images of some parts of Antarctica were added in June 2007 for the first time). The tiling system produces artifacts near the poles as the tiles become 'infinitely' small and rounding errors accumulate. Cloud cover and shadows can make it difficult or impossible to see details in some land areas, including the shadow side of mountains. Former Indian president APJ Abdul Kalam had expressed concern over the availability of high-resolution pictures of sensitive locations in India. The South Korean govt. expressed concern that GE offers images of the presidential palace and various military installations that could possibly be used by their hostile neighbor North Korea. The Area 51 base in the Nevada desert is clearly visible, with no evidence of intentional obstruction or blurring. The base's runways and even a number of planes are visible. As a result of pressure from the United States government, the residence of the Vice President at Number One Observatory Circle is obscured through pixelization in Google Earth and Google Maps. National security and privacy issues A web mapping service provided as a part of Microsoft's Windows Live online applications services. The application is a typical Web 2.0 application, providing the user experience of a desktop application, with functionality like drag and drop, smoothly opening menus etc. Though the application is web based, it is not independent of OS. 3D visualizer, runs only under MS Windows. The resolution of the imagery varies from place to place - best available for USA, Canada, U.K. & Australia. VIRTUAL EARTHGOOGLE EARTH Microsoft Windows XP (SP-2), MS Windows Server 2003/ Windows Vista. Windows (2000/XP/Vista), Linux and MacOSX, Linux, MacOSX Microsoft Internet Explorer 6 / 7 (now Mozilla Firefox) Its a stand alone application. 1.0 GHz processor (2.8 GHz or faster recommended), 250 MB or more of hard disk space Unlikely to operate on older hardware configurations. 256 MB of system memory (1 GB recommended)Pentium 3, 500 MHz, 128 MB RAM 400 MB free disk space 32 MB video card (256 MB recommended) that supports Microsoft DirectX 9, with 3D hardware acceleration enabled 16MB 3D-capable graphics card. Resolution of 1024x768, 16-bit High Color High speed / broadband Internet connectionNetwork speed: 128 kbps Google Earth Interface after startup Microsoft Virtual Earth Interface after startup GE downloaded & installed as client side application. VE runs in Internet Explorer 6/7 (also in mozilla firefox now) & to view 3D content an ActiveX control has to be installed. GE initialization takes less time compared to VE. Speed of zooming in to a location & display of appropriate data is faster in GE, although VE seems to be using tiling of data too. GOOGLE EARTHMS WINDOWS LIVE LOCALVIRTUAL EARTH 3D Introduction year OS - Windows, Mac, Linux, UnixYES, YES, YES, NOYES, NO, NO, NO Program/data licenseProprietaryPropriety Multiple datasetsNo Street map overlayYesSome School, Restaurant and Hotel guidesYesNo Transportation guidesYes Park guidesYesNo Satellite and aerial image overlayYes Weather map overlayNo Topographic map overlaySomeNo Real-time traffic reportYesNo GPS-integrationYesNo Distance measureYes Drawing toolsYesNo Movie makerYesNo GOOGLE EARTHMICROSOFT WINDOWS LIVE LOCALVIRTUAL EARTH 3D 3D graphicsYes 3D building modelsYes Terrain modelsYes Sea-floor modelsNo PlanetariumYes Day/night viewsYesNo Imagery of other planetsNo Telescope/Sky modeYesNo Local sky viewYesNo Online community user inputYesNo ExtensibilitySomeNo Wikipedia integrationYesNo GOOGLE EARTH MICROSOFT WINDOWS LIVE LOCALVIRTUAL EARTH 3D Languages supported German, Dutch, English, Spanish, French, Italian, Japanese (with Help support in Arabian, Czechian, Korean, Brazilian Portuguese, Polish, Russian)English 3D buildings Yes (United States)Yes High resolution dataset areas Yes: Australia, Belgium, Canada, China, Denmark, France, Germany, Italy, Japan, Netherlands, Spain, United Kingdom, United States Some: United States, Canada, United Kingdom, Italy, France, Australia, Germany Street level address search areas Yes: Australia, Belgium, Brazil, Canada, China, Czechia, Danmark, Estonia, France, Germany, Hungary, Italy, Japan, Lithuania, Netherlands, Poland, Spain, United Kingdom, United States Driving direction areas Yes: Australia, Belgium, Canada, China, Danmark, France, Germany, Italia, Netherlands, Spain, United Kingdom, United StatesSome: United States, United Kingdom, Australia Business listing areas Yes: Australia, Belgium, Canada, China, Danmark, France, Germany, Italia, Japan, Netherlands, Spain, United Kingdom, United StatesNo Hotel listing areas Yes: Australia, Belgium, Canada, China, Danmark, France, Germany, Italia, Japan, Netherlands, Spain, United Kingdom, United StatesNo Resolution of VE imagery better than GE for US, India GE imagery better & Europe both comparable. The labeling of context area, lakes, cities etc is better in VE. Even at largest scale the name of city is displayed at a corner in VE, whereas in GE only local streets & searched location are labeled. The Parks and recreational areas are labeled in the Virtual Earth even at very small scale, whereas in GE they are depicted as icons. The labels for water features too appear even at very small scale in case of Virtual Earth but in case of Google earth the features are labeled at large scale only. VE features LOCATE ME - which requires installation of an extra plugin; is used to locate the user automatically (by resolving the IP address). LOCATE ME is not much accurate i.e. testing its functionality in WP apartments, we were located in West Campbell. The layers can be turned On & Off as per the users choice GE thus enables user to choose the level of detail they require in terms of information. Whereas in VE all layers are controlled by the application and the user cannot control the level of information on screen. The user can create a polygon, path and image overlay in GE, whereas in VE no such functionality exists. With GE, once an image is downloaded, it takes much shorter period to zoom in or out ;Whereas VE3D reloads the images every time. VIRTUAL EARTHGOOGLE EARTH VE3D is more usable now as it supports SpaceNavigator GE is also better with a SpaceNavigator Tiling approach for rendering aerial and satellite photos is very annoying one can see "chunks" of imagery load & unload as one moves along or zoom. GE's graphics engine has been refined over several years & the technology seems more pleasing to eyes i.e. transitions between imagery is smoother. BE view offers aerial photos from 4 points. These Pictometry images are much more detailed than the aerial views from directly above buildings. It has no real equivalent to BE views. Technology for automatically generating 3D buildings is better than Google's approach for capturing entire cities in 3D. The amount of 3D Building data is impressive in scale, and quite decent in quality until you get closer to the buildings. Google has been asking community at large to build 3D buildings & share them through their 3D Warehouse. This approach seems to be working to a degree but only a small percentage of a city will be built typically using this approach. Virtual Earth uses a Cylindrical Mercator projection. (As a reference datum both information systems use the WGS84) Uses the Cylindrical Plate Carree projection. (As a reference datum both information systems use the WGS84) One unified Javascript API for both 2D and 3D maps - same javascript used to manipulate VE in 2d is used to instantiate the map control & switch to 3d. Google separates 2 applications : GE, a 3d viewer & Google Maps, a 2d viewer. Only Google Maps can be inside a web- browers, while GE is a program. Thus two different APIs exist for both. VIRTUAL EARTHGOOGLE EARTH TILING APPROACH for rendering aerial and satellite photos is very annoying one can see "chunks" of imagery load & unload as one moves along or zoom. GE's graphics engine refined over years & the technology seems more pleasing to eyes i.e. transitions between imagery is smoother. BIRD EYE VIEW offers aerial photos from 4 points. These images are much more detailed than aerial views from directly above buildings. No real equivalent to BE views. Not many data layers - have "Maps" & "Hybrid" layers showing information of roads, road labels, borders & country names. Also information for points of interests like restaurants, but not much information in this area. Huge no. of built-in layers, esp. points of interest : Airports, railways, ferry routes, restaurants, lodging, etc. Also, data from organizations like National Geographic Magazine, Discovery Channel, UNEP, AIA etc. Virtual Earth uses a Cylindrical Mercator projection.Uses the Cylindrical Plate Carree projection. (Reference datum for both - WGS84) One unified Javascript API for both 2D and 3D maps - same javascript used to manipulate VE in 2d is used to instantiate the map control & switch to 3d. 2 different APIs exist : GE, a 3d viewer & Google Maps, a 2d viewer. Only Google Maps can be inside a web- browers, while GE is a program. Focus of this comparison is from a user perspective, not a developer Microsofts exclusive 45 BE View. Major U.S. Counties covered by BEs view: Arkansas (Bentonville) California Los Angeles, Orange County, & San Francisco Colorado (Broomfield County) District of Columbia District of Columbia Florida Duval (Orlando) Georgia Fulton (Atlanta) Indiana Marion (Indianapolis) Kansas Wyandotte Kentucky Fayette (Lexington) Louisiana Orleans, Lincoln County Maryland Baltimore City Massachusetts Suffolk County (Boston) Minnesota (Dakota & Olmsted County) Nevada Clark County (Las Vegas) New Mexico Bernalillo (Albuquerque) New Jersey Hudson, Lawrenceville & Trenton New York Erie, New York, & Suffolk Ohio Hamilton Tennessee (Coming Soon) Texas (Fort Worth) Pennsylvania Philadelphia, Montgomery County Washington King County (Seattle) Microsofts exclusive 45 BE View. Major U.S. Counties covered by BEs view: Arkansas (Bentonville) California Los Angeles, Orange County, & San Francisco Colorado (Broomfield County) District of Columbia District of Columbia Florida Duval (Orlando) Georgia Fulton (Atlanta) Indiana Marion (Indianapolis) Kansas Wyandotte Kentucky Fayette (Lexington) Louisiana Orleans, Lincoln County Maryland Baltimore City Massachusetts Suffolk County (Boston) Minnesota (Dakota & Olmsted County) Nevada Clark County (Las Vegas) New Mexico Bernalillo (Albuquerque) New Jersey Hudson, Lawrenceville & Trenton New York Erie, New York, & Suffolk Ohio Hamilton Tennessee (Coming Soon) Texas (Fort Worth) Pennsylvania Philadelphia, Montgomery County Washington King County (Seattle) Coming SoonComing Soon BE view offers aerial photos from 4 pts which are much more detailed than the standard straight down aerial views (signs on top of buildings, advertisements, pedestrians etc are clearly visible). MS uses an aircraft equipped with a vexcel aerial camera to capture birds eye footage. Google's models look cartoonish because color & brightness dont match the underlying imagery. The textures could possibly be shaded to match the histograms of the imagery beneath which would create more perceptual realism without loss of such custom quality. Perception within an environment is the difference between something looking realistic and non-realistic MS's buildings better matched tonally to their surroundings & to each other, thus look better from a distance. The fact that they have modeled even minor buildings really makes cities come alive. Comparison: Denver, Colorado capitol building in VE (AUTO GENERATED) to the HAND-BUILT BUILDING in GE Same building with cityscape in background & a close-up view. Note: Auto-generated textures in VE3D do not look very good in close-up view whereas there is a great detail in the hand-made GE model (esp. if you zoom in close). Part of the problem with VE3D view is due to MS's decision not to load too many texture details as it consumes a lot of memory space. On older machines, Google's approach will greatly overload the system causing much slower performance. In VE advantages of automatically generating 3D buildings is to have vast majority of buildings modeled (more cities) at a better cost per city. Disadvantage is that the level of detail and accuracy (at least currently shown) in VE3D is lower when examined closely. Googles Hand-made approach doesnt scale well in order to have 3D buildings for each city. With free Google SketchUp 3D modeling tool it is allowing people to upload models to their 3DWarehouse. This is working well for larger & more interesting buildings but won't work for all the buildings. MS's approach (Auto-generation of 3D buildings) is to take multiple aerial photos, using photogrammetry calculate size- shape of buildings, extract 3D building models & use these photos to texture them. MS's huge investment to acquire & develop technology, buy camera assets, hire teams of aerial photographers to collect the data & the storage- processing costs will ultimately enable them to create building models for nearly all cities in a scaleable fashion. In VE3D you can permalink any view as a URL and then send it, save it, or bookmark it. Better than making a placemark in GE, adding a snapshot view, and sending/ saving for GE one has to download a KML file first to desktop where it sits superfluously until its trashed. Permalink is for consumers who regularly conduct the same searches or who want to share specific searches with others. By clicking the Permalink link, a URL is created that can be used to return to MSN VE later and re-create map view and searches. Permalink link can be bookmarked,ed to a friend or copied into a clipboard. Microsoft sees end users more as consumer that needs to be catered. VE3D's buildings, have been textured automatically and systematically. Google sees end user as content contributor Its default buildings are basic gray shapes, with end users encouraged to build their own textured masterpieces & share them through Google community and its 3D Warehouse. Which strategy will prevail ??? We think Google will eventually have to offer textured buildings by default. Microsoft has teamed up with 3D Dassault Systemes (DS) to launch Microsft Virtual Earth 3DVIA. Microsoft has teamed up with 3D Dassault Systemes (DS) to launch Microsft Virtual Earth 3DVIA. This free online application allows consumers to imagine and create realistic 3-D models for instance buildings and structures then share them through Microsoft Virtual Earth and online communities. This free online application allows consumers to imagine and create realistic 3-D models for instance buildings and structures then share them through Microsoft Virtual Earth and online communities. Users can design a 3-D model of their house, favourite building or any structure, then select from different visualisation options, textures and colours to give their 3-D model a style of its own. Users can then upload their 3-D models to VE, specifying an address or neighborhood so they can experience the model within a real-life context. Users can design a 3-D model of their house, favourite building or any structure, then select from different visualisation options, textures and colours to give their 3-D model a style of its own. Users can then upload their 3-D models to VE, specifying an address or neighborhood so they can experience the model within a real-life context. Although MS still doesnt have nearly the amount of coverage of world with high resolution aerial photos as Google, the amount of data they have added is significant. BE views in particular add several times as much photography for a given city as the standard straight-down views. So, for any given city where MS has BE views they have more aerial data than Google. And MS is adding cities with this data at an amazing rate. Thus, MS has decided advantage in terms of BE photography data, implementation for viewing it & for massive amount of new 3D & aerial imagery they've been adding. Still this is not a major threat to the continuing popularity of GE as the overall user interface, smoothness, usefulness, and massive amounts of very useful data in GE continues to outshine what MS has built so far. Google Earth has very little functionality of a commercial GIS - known as a laymans GIS. GE provides basic GIS functionality such as finding driving directions, locating a place & finding a business in a neighborhood. More experienced GIS users can create polygons, paths, place marks and perform image overlays - can be compared to digitization techniques offered by commercial GIS softwares but these features do not have any functionality other than visualization in GE. They can have a description attached to them but no attributes. The image overlays can be used to do visual interpretation of data but not spatial analysis. The paid GE Pro allows import of GIS data. The supported vector file formats are MapInfo (.TAB) & ESRI (.SHP). Raster file formats supported are TIFF (.tiff), National Imagery Transmission Format (.ntf), Erdas Imagine Images (.img). Although GIS data can be imported in GE but its attribute information cannot be edited after importing it which limits use of spatial data to just visualization. These files to be imported must have the projection information attached to it, although GE projects data on WGS84 coordinate system. However, imagery without the projection information can also be imported in GE but the coordinates have to be manually edited. The supported file formats for this are Atlantis MFF Raster (.hdr), PCIDSK Database File (.pix), Portable Pixmap Format (.pnm), and Device Independent Bitmap (.bmp). Another interesting feature is the ruler, which can be used to calculate the length of a line, path and area of a polygon, circle - available only in paid GE Pro version. This feature can used to locate a nearest facility and get the distance to get there, manually. Whereas, a similar operation in GIS is totally automated. GE lacks data analysis aspects and unless incorporated GE will just remain a laymans GIS. ARCSCENE Requires ArcGIS Desktop and the extension 3D Analyst. Entire 3D scene is loaded into memory so it has memory limitations, thus can only be used to view smaller 3D scenes. ARCGLOBE Also requires ArcGIS Desktop and the extension 3D Analyst. Only loads current view into memory, thus supports loading large amounts of data. It has a single elevation surface and requires data to project it correctly on the globe. COMPARISON OF ARCSCENE TO ARCGLOBE: -Both can make 3D fly-through animations. ArcScene has some additional layer animation capabilities, such as moving a layer in space. -Only ArcGlobe uses the Publisher extension to create a portable 3D scene that can be read in ArcReader. -Both have access to the ArcGIS Toolbox for analytical use. -ArcScene is more flexible in these areas and is better suited for underground visualization. ArcGlobe is good for terrain datasets. ARCGIS EXPLORER It is a lighter tool for consuming content from ArcGIS Server and running analytical tasks published by ArcGIS Server. Google Earth Vs ArcGIS Explorer: In AGE locations can be interactively located using a pointer tool & located address can be dragged into search box, instead of typing it. AGE has option to click on a location & find its address (currently available for US & Canada only). In AGE a line & a path can be measured, and latitude, longitude & elevation of a point can be found too. In AGE there is an option of finding a route with multiple stops in AGE, whereas no such option in GE. Water features & parks not labeled in AGE at any scale, whereas labeled at large scales in GE. The streets are labeled even at the largest scale in GE whereas in AGE street labels are turned off, much before the largest extent possible. Only 3 layers (imagery, transportation & boundaries) available in AGE, whereas in GE numerous layers available. GIS data can be added to AGE, whereas it can be added in the paid GE Pro version only. AGE has more GIS functionality than GE, although user interface & streaming of data is better in GE. ArcGIS Explorer at startup Both are client side application. In AGE double click of mouse doesnt zoom in to a given location & the user can zoom in using zoom in slider. Initialization of AGE takes a longer comparatively. The speed of zooming in to a location is better in GE. The resolution of imagery for US is comparable whereas for Europe & India, GE imagery is of very high resolution compared to very low resolution imagery of AGE. GE is user friendly application which is bringing basic GIS tasks to common internet users but it doesnt have any spatial analysis functionality yet, which limits its users. At present, the streaming of imagery & speed of browsing is better in GE & unparalleled. There is a long way to go, before any of these applications can integrate sophisticated GIS technology in web mapping with minimal cost for the user. GE is just a visualization tool, however it has included new GIS functionality slowly & steadily ever since its launch (features like creation of polygon, path & importing of GIS data has been added in recent versions). Thus, it cannot be denied that Google Earth is being updated to compete with commercial GIS softwares at a very low price. Integration of complex GIS functionalities in web GIS is being actively pursued, and many competitor applications are coming up. ArcGIS Explorer seems to be a good competitor for GE, as it integrates more GIS functionality. Virtual Globe is Changing the Way We See the World AECnews.com. Google earth: The people's GIS. Available fromButler, Declan. Declan Butler - reporter. Available fromEarth, Google. Google earth Commuinty. Available fromEarth, Google. Google Earth User Guide. Available fromEarth, Google. Google Earth website. Available fromESRI. ArcGIS Explorer Download page. Available from380/explorer/software/downloadpage.html380/explorer/software/downloadpage.html. Flood, Brian. Brian Flood Blog. Available fromblogs/brian_flood/archive/2005/08/19/72.aspxblogs/brian_flood/archive/2005/08/19/72.aspx. Microsoft. Microsoft Virtual Earth. Available fromTaylor, Frank. Google Earth Blog. Available fromWikipedia. Google Earth- Wikipedia. Available from THANK YOU Presented by: Abhishek Kala, Bhavna Kalla, Vineeth Viswanathan